Mid-Term Clinical Outcomes of Mobile-Bearing UKA: A Retrospective Study on the Influence of Patellofemoral Joint Disease, Lower Limb Alignment, and Implant Positioning

Mid-Term Clinical Outcomes of Mobile-Bearing UKA: A Retrospective Study on the Influence of Patellofemoral Joint Disease, Lower Limb Alignment, and Implant Positioning | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Mid-Term Clinical Outcomes of Mobile-Bearing UKA: A Retrospective Study on the Influence of Patellofemoral Joint Disease, Lower Limb Alignment, and Implant Positioning Mingkang Chen, Changqing Zhang, Zelin Fan, Jian Peng, Wei Xu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8496530/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 20 You are reading this latest preprint version Abstract Background Unicompartmental knee arthroplasty (UKA) has become an effective treatment for medial compartment osteoarthritis of the knee. However, its use in patients who also have patellofemoral joint osteoarthritis (PFOA) before surgery remains controversial. Restoring postoperative lower limb alignment and achieving accurate implant positioning are also important factors for the success of UKA, but there is still a lack of studies that combine both patient-related factors and surgical technique-related factors in the Chinese population. Methods This study retrospectively analyzed 69 Chinese patients (79 knees) with medial compartment osteoarthritis who underwent Oxford UKA between May 2017 and December 2020. The severity and location of PFOA were assessed by MRI. Postoperative coronal alignment was categorized by the femorotibial angle (FTA) into neutral, mild varus, moderate varus, and extreme/out-of-range groups. Implant positioning was classified as ideal or non-ideal according to established radiographic target ranges for aLDFA, aMPTA, PTS, and component alignment angles. Functional outcomes were evaluated using VAS, KSS, WOMAC, and Kujala score. Results Oxford UKA markedly improved patient function, and at an average follow-up of 66.5 ± 9.6 months, no cases of prosthesis loosening or revision were observed. Postoperative functional scores did not differ by PFOA severity or lesion location. Regarding lower-limb alignment, neutral and mild varus (< 6°) knees had higher KSS-function than moderate varus and extreme/out-of-range knees and lower WOMAC scores. KSS-knee were higher in neutral and mild varus than in the extreme group. Implant positioning (ideal vs non-ideal) was not associated with postoperative scores. Conclusion Mid-term follow-up showed that Oxford UKA achieved satisfactory clinical outcomes. The severity and location of PFOA before surgery did not significantly affect postoperative knee function. Maintaining postoperative alignment within the target range (neutral to slight varus; within 6° of varus) may be associated with better functional recovery. Unicompartmental knee arthroplasty (UKA) Patellofemoral Joint Disease Lower Limb Alignment Implant Positioning Clinical Outcomes Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Unicompartmental knee arthroplasty (UKA) has been developed over many years. Many studies have shown that, compared with total knee arthroplasty (TKA), UKA has advantages such as being less invasive, preserving joint position sense, promoting faster recovery, and achieving higher patient satisfaction[ 1 ]. However, the indications for UKA are still debated. One major point of controversy is whether patients who have patellofemoral joint osteoarthritis (PFOA) before surgery are suitable candidates for UKA. The study by Lu[ 2 ] suggested that patients who have PFOA found during surgery or through preoperative imaging, but who do not show signs of lateral patellofemoral groove involvement, should not be considered contraindicated for UKA. In contrast, the study by Andronic[ 3 ] reported that patients with lateral PFOA may have a higher risk of later revision after UKA. A systematic review and meta-analysis by Yang[ 4 ] found that preoperative PFOA is generally not linked to inferior function or implant survival after UKA. Nonetheless, heterogeneity in implant type, PFOA assessment, and follow-up persists, and data are still scarce for Oxford mobile-bearing UKA with standardized imaging-based grading of PFOA severity and location in Chinese cohorts. For patients, whether choosing UKA or TKA, the accuracy of the surgical technique is an important factor that affects implant survival and functional outcomes. This includes restoring lower limb alignment after surgery and placing the implant in the correct position[ 5 ]. Some researchers believe that improving surgical precision and using computer-assisted technology may help restore alignment and improve the accuracy of implant placement[ 6 , 7 ]. However, Kennedy[ 8 ] reported, in a large cohort, that postoperative limb alignment was not associated with functional outcomes or revision risk after Oxford medial UKA. Around 2016, the Oxford UKA technique began to be widely introduced in China, and its clinical use has since expanded. However, there is still a lack of studies in Chinese patients that analyze the effects of lower limb alignment, and implant positioning on the outcomes of UKA. However, the impact of pronounced malalignment outside the target window (e.g., valgus or severe varus outliers) on patient-reported outcomes in routine practice remains unclear, especially when patient- and technique-related factors are assessed concurrently. Although MRI is not routinely recommended as a mandatory imaging modality for preoperative evaluation before Oxford UKA[ 9 ], obtaining an ideal lateral radiograph is often challenging, making it difficult to accurately assess the presence of anteromedial osteoarthritis and the integrity of the anterior cruciate ligament. Therefore, magnetic resonance imaging (MRI) was performed in most patients with knee osteoarthritis in our cohort. In addition, patellofemoral joint disease is relatively common in the Chinese population[ 10 ], and MRI provides excellent visualization of patellofemoral pathology. In this study, we retrospectively evaluated a Chinese cohort undergoing third-generation Oxford medial UKA to examine the associations of MRI-defined PFOA severity and location, postoperative limb alignment, and implant positioning with mid-term functional outcomes. Materials and Methods Patient cohort This study was approved by our institutional ethics committee (Approval Document No. JD-HG-2025-131) and retrospectively reviewed all consecutive patients who underwent cemented third-generation Oxford medial unicompartmental knee arthroplasty at our hospital from May 4, 2017, to December 21, 2020. Eligible cases were identified from institutional surgical records/electronic medical records, and imaging data were retrieved from the picture archiving and communication system. All patients met the surgical indications for medial UKA: patients had medial compartment osteoarthritis with no symptoms in the lateral compartment; flexion contracture was less than 15 degrees, and joint range of motion was preserved; varus deformity was less than 15 degrees and could be passively corrected. Inclusion criteria were patients who underwent UKA due to medial compartment osteoarthritis, with available preoperative MRI and weight-bearing anteroposterior and lateral knee radiographs, as well as postoperative anteroposterior and lateral knee radiographs. Exclusion criteria included imaging data that did not meet study requirements, lateral patellofemoral trochlear groove changes, and secondary osteoarthritis. Anterior knee pain alone was not considered an absolute contraindication. The STROBE flow diagram summarizes the screening process, including the number of excluded cases with specific reasons. The details are further illustrated in an additional figure file [see Additional file 1]. Data analysis Two orthopedic surgeons evaluated the preoperative and postoperative anteroposterior and lateral knee radiographs, as well as preoperative knee MRI. Preoperative tibiofemoral osteoarthritis severity was graded on weight-bearing anteroposterior knee radiographs using the Kellgren–Lawrence (K–L) classification (grades 0–4). Grading was performed independently by two orthopedic surgeons who were blinded to postoperative outcomes; disagreements were resolved by consensus. The femorotibial angle (FTA) was defined as the lateral angle formed by the anatomical axis of the femur (a line through the center of the femoral medullary canal) and the anatomical axis of the tibia (a line through the center of the tibial medullary canal) (Fig. 1 ). The normal FTA is approximately 173 degrees. The degree of varus was calculated as FTA minus 173 degrees, with positive values indicating varus[ 11 ]. Based on postoperative FTA, patients were categorized into four groups: neutral alignment (≥ 173° and < 176°), mild varus (≥ 176° and < 179°), moderate varus (≥ 179° and < 182°), and an extreme/out-of-range group (< 173° or ≥ 182°). The extreme/out-of-range group was defined as patients with marked deviation from the intended postoperative alignment window. Because valgus and severe varus outliers were few, they were pooled to improve estimate stability and statistical power, while descriptive results for valgus and severe varus were also presented separately when appropriate. Postoperative anteroposterior and lateral radiographs were used to measure implant positioning parameters, including anatomic lateral distal femoral angle (aLDFA), anatomic medial proximal tibial angle (aMPTA), posterior tibial slope (PTS), coronal femoral component angle (c-FCA), and sagittal femoral component angle (s-FCA) (Figs. 2 and 3 ), based on previously published methods[ 12 – 16 ]. The ideal ranges defined by previous studies and consensus were as follows[ 17 ]: aLDFA 79° to 83°, aMPTA 85° to 90°, PTS 83° to 87°, c-FCA − 3° to 3°, and s-FCA 0° to 10°. Cases with implant alignment values within these ranges were classified as the "ideal value group," and those outside these ranges were classified as the "non-ideal value group." Preoperative knee MRI was used to assess the severity and location of patellofemoral joint disease. The Outerbridge classification system was used to evaluate the severity of patellofemoral cartilage damage (grade 0: normal cartilage; grade 1: cartilage softening; grade 2: moderate cartilage fibrillation with fissures less than 1.3 cm; grade 3: severe cartilage fibrillation with fissures greater than 1.3 cm; grade 4: subchondral bone exposure) (Fig. 3 )[ 18 ]. Patients were classified into three groups: no PFOA (grade 0), mild PFOA (grades 1–2), and moderate to severe PFOA (grades 3–4). Based on the location of cartilage damage on the patellofemoral articular surface, patients were further categorized as medial and central PFOA (lesions in the medial two-thirds of the patellofemoral surface) or lateral PFOA (lesions in the lateral one-third). All imaging measurements were performed using AutoCAD 2026. Functional evaluations included the Visual Analog Scale (VAS) for pain[ 19 ]; the Knee Society Score (KSS), consisting of knee score and function score; the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), which includes pain, stiffness, and daily activity subscales, with higher scores indicating more severe symptoms[ 20 ]; and the Kujala score for anterior knee pain, with higher scores indicating better knee function and less pain[ 21 ]. A two-way random-effects model was used to calculate the intraclass correlation coefficient (ICC) to evaluate interobserver and intraobserver reliability. Both interobserver and intraobserver assessments included all patients, and the repeated measurements were performed one week after the initial evaluation. The ICC values for all angle measurements were good (0.75 to 0.90) or excellent (> 0.90) (Table 1 ). Table 1 Intra-observer and inter-observer reliability of radiographic measurements Intra-observer Inter-observer FTA Preoperative Postoperative 0.99(0.98-1.00) 0.98(0.96–0.99) 0.99(0.97–0.99) 0.97(0.90–0.96) aLDFA Preoperative Postoperative 0.89(0.82–0.93) 0.86(0.78–0.90) 0.87(0.80–0.91) 0.84(0.72–0.89) aMPTA Preoperative Postoperative 0.91(0.85–0.95) 0.88(0.86–0.92) 0.94(0.89–0.97) 0.85(0.78–0.90) PTS Preoperative Postoperative 0.93(0.88–0.96) 0.95(0.91–0.97) 0.97(0.90–0.99) 0.95(0.87–0.97) c-FCA 0.90(0.84–0.94) 0.80(0.60–0.93) s-FCA 0.92(0.86–0.96) 0.81 (0.72–0.86) Footnotes: Values are intraclass correlation coefficients (ICC) with 95 percent confidence intervals. ICC values of 0.75–0.90 indicate good reliability, and values above 0.90 indicate excellent reliability.FTA, femorotibial angle; aLDFA, anatomic lateral distal femoral angle; aMPTA, anatomic medial proximal tibial angle; PTS, posterior tibial slope; c-FCA, coronal femoral component angle; s-FCA, sagittal femoral component angle. Statistical Analysis All data were checked by a designated reviewer after entry. Based on the results of the normality test, independent sample t-tests were used for continuous variables with normal distribution, and the Mann–Whitney U test was used for data with non-normal distribution. Categorical variables were compared using the chi-square test. Multivariate analysis of variance (MANOVA) was used to evaluate the overall effects of PFOA grade, FTA grouping, and their interaction on multiple postoperative functional outcomes, including VAS, KSS, WOMAC, and Kujala scores. For factors showing significant effects in the MANOVA, further analysis was performed using analysis of covariance (ANCOVA) to determine their specific effects on each functional score. A p value of less than 0.05 was considered statistically significant. All statistical analyses were performed using SPSS version 27.0. Results Baseline characteristics of patients A total of 69 eligible patients (79 knees) were included in this study. The average follow-up time was 66.5 ± 9.6 months. The mean age at the time of surgery was 62.2 ± 8.0 years. The mean BMI was 25.7 ± 3.4 kg/m². The study group consisted of 54 female patients and 15 male patients. Preoperatively, tibiofemoral osteoarthritis was end-stage in nearly all knees: 76/79 (96.2%) were graded as K–L grade 4, and 3/79 (3.8%) as K–L grade 3. The distribution of K–L grades did not differ significantly among groups. Demographic and clinical data were analyzed and compared across groups (Tables 2 , 3 , 4 , 5 , and 6 ). Table 2 Patient demographics and baseline characteristics by PFOA severity. Characteristic Overall Cohort No PFOA Mild PFOA M/S PFOA N 79 16 49 14 Demographics Mean Age 62.2 ± 8.0 62.8 ± 8.7 62.2 ± 8.1 61.6 ± 7.2 % Male(n) 19.0(15) 18.8(3) 12.2(6) 42.9(6) Mean BMI 25.7 ± 3.4 25.3 ± 2.9 25.8 ± 3.7 26.2 ± 3.0 Mean Follow-up 66.5 ± 9.6 70.5 ± 6.0 65.7 ± 11.3 64.9 ± 4.0 Preoperative clinical scores Mean VAS 7.6 ± 1.0 7.4 ± 1.2 7.6 ± 0.9 8.0 ± 0.8 Mean KSS-F 53.7 ± 3.1 54.0 ± 2.7 b 54.3 ± 2.8 b 50.9 ± 3.2 Mean KSS-K 54.9 ± 2.8 54.9 ± 2.8 55.6 ± 2.5 b 52.4 ± 2.4 Mean WOMAC 45.4 ± 2.9 44.3 ± 3.1 b 45.4 ± 3.0 46.8 ± 1.9 Mean Kujala 61.1 ± 4.5 65.0 ± 3.4 ab 61.9 ± 2.6 b 54.1 ± 3.6 Preoperative radiographic c- haracteristics %K–L grade IV(n) 96.2(76) 100.0(16) 95.9(47) 92.9(13) FTA 180.1 ± 3.3 179.0 ± 3.3 180.6 ± 3.3 179.9 ± 3.0 Mean aLDFA 82.0 ± 1.9 81.4 ± 2.3 82.3 ± 1.9 81.4 ± 1.6 Mean aMPTA 85.4 ± 2.1 85.7 ± 2.2 85.5 ± 2.2 84.5 ± 1.7 Mean PTS 84.0 ± 3.8 83.6 ± 3.9 84.0 ± 3.9 84.7 ± 3.8 Footnotes: a: The difference was statistically significant compared to the mild PFOA group; b: The difference was statistically significant compared to the moderate-to-severe PFOA group. The values are given as the mean and standard deviation.PFOA, patellofemoral osteoarthritis; M/S PFOA, moderate-to-severe PFOA; BMI, body mass index; VAS, Visual Analog Scale for pain; KSS-F, Knee Society Score – function; KSS-K, Knee Society Score – knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index. Table 3 Postoperative clinical outcomes by PFOA severity. Overall Cohort No PFOA Mild PFOA M/S PFOA Mean VAS 0.7 ± 0.7 0.7 ± 0.6 0.7 ± 0.8 0.8 ± 0.6 Mean KSS-F 83.6 ± 3.4 83.3 ± 3.3 83.9 ± 4.2 82.9 ± 2.4 Mean KSS-K 83.6 ± 3.7 83.4 ± 3.1 83.5 ± 3.8 83.9 ± 2.5 Mean WOMAC 5.0 ± 2.9 5.6 ± 2.3 4.8 ± 3.3 4.9 ± 2.3 Mean Kujala 84.4 ± 2.7 84.0 ± 2.4 84.6 ± 3.0 84.4 ± 1.6 Footnotes: There were no statistically significant differences in postoperative functional scores among the three PFOA severity groups (p > 0.05). The values are given as the mean and standard deviation. PFOA, patellofemoral osteoarthritis; M/S PFOA, moderate-to-severe PFOA; VAS, Visual Analog Scale; KSS-F, Knee Society Score – function; KSS-K, Knee Society Score – knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index. Table 4 Clinical outcomes based on the location of PFOA. Mid-medial PFOA Lateral PFOA p N 41 22 Demographics Mean Age 62.4 ± 7.8 61.5 ± 8.1 0.662 % Male(n) 19.5(8) 18.2(4) Mean BMI 25.2 ± 2.6 27.0 ± 4.7 0.158 Mean Follow-up 64.2 ± 11.2 68.0 ± 7.4 0.031 %K–L grade IV(n) 95.1(39) 95.5(21) Preoperative clinical scores Mean VAS 7.6 ± 0.9 7.9 ± 0.9 .193 Mean KSS-F 53.5 ± 3.2 53.7 ± 3.3 .819 Mean KSS-K 55.0 ± 2.9 54.6 ± 2.6 .519 Mean WOMAC 45.2 ± 2.9 46.8 ± 2.5 .084 Mean Kujala 61.7 ± 4.3 60.5 ± 4.8 .237 Postoperative clinical scores Mean VAS 0.7 ± 0.6 0.8 ± 1.0 .830 Mean KSS-F 83.9 ± 3.4 83.3 ± 4.6 .919 Mean KSS-K 83.8 ± 3.3 83.2 ± 4.0 .680 Mean WOMAC 4.7 ± 2.4 5.1 ± 4.1 .642 Mean Kujala 84.6 ± 2.5 84.2 ± 2.8 .645 Footnotes: Mid-medial PFOA indicates lesions involving the medial and central two-thirds of the patellofemoral articular surface; lateral PFOA indicates lesions located in the lateral one-third. There were no significant differences in postoperative functional outcomes between the two groups (p > 0.05). The values are given as the mean and standard deviation. VAS, Visual Analog Scale; KSS-F, Knee Society Score – function; KSS-K, Knee Society Score – knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index. Table 5 Comparison of clinical outcomes by postoperative lower limb alignment groups. Neutral Mild varus Moderate varus Extreme/out-of-range N 19 25 23 12 Demographics Mean Age 59.6 ± 8.9 62.7 ± 7.9 63.7 ± 7.9 62.6 ± 6.6 % Male (n) 15.8(3) 24.0(6) 13.0(3) 25.0(3) Mean BMI 26.7 ± 4.4 24.8 ± 2.8 26.5 ± 3.1 24.9 ± 3.3 Mean Follow-up 66.5 ± 8.4 65.2 ± 8.5 65.6 ± 12.3 71.1 ± 6.9 %K–L grade IV(n) 94.7(18) 96.0(24) 95.7(22) 100.0(12) Preoperative clinical scores Mean VAS 7.7 ± 1.0 7.8 ± 1.0 7.5 ± 0.8 7.4 ± 0.8 Mean KSS-F 52.9 ± 3.5 53.8 ± 3.3 53.8 ± 2.7 54.1 ± 2.8 Mean KSS-K 54.7 ± 2.8 55.0 ± 2.9 54.9 ± 2.5 54.7 ± 3.3 Mean WOMAC 45.8 ± 2.5 45.2 ± 2.9 45.1 ± 2.6 45.9 ± 4.1 Mean Kujala 60.2 ± 4.9 61.6 ± 4.8 61.5 ± 4.1 60.9 ± 4.6 Postoperative clinical scores Mean VAS 0.8 ± 0.6 0.7 ± 0.7 0.7 ± 0.6 0.8 ± 1.2 Mean KSS-F 84.3 ± 2.4 ab 86.1 ± 2.8 ab 81.8 ± 3.1 80.7 ± 4.6 Mean KSS-K 84.7 ± 2.6 a 84.4 ± 3.1 a 83.1 ± 2.9 80.8 ± 4.6 Mean WOMAC 4.0 ± 2.3 ab 3.2 ± 1.7 ab 6.3 ± 1.6 7.8 ± 4.5 Mean Kujala 84.7 ± 2.0 a 85.4 ± 2.3 a 84.4 ± 2.3 82.1 ± 3.7 Footnotes: a = significantly different compared with the extreme/out-of-range group (p < 0.05); b = significantly different compared with the moderate varus group (p < 0.05). The values are given as the mean and standard deviation. The valgus/severe varus group represents an extreme/out-of-range alignment category (< 173° or ≥ 182°) and does not imply biomechanical equivalence between valgus and severe varus. FTA, femorotibial angle; VAS, Visual Analog Scale; KSS-F, Knee Society Score – function; KSS-K, Knee Society Score – knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index. Table 6 Postoperative functional outcome comparison between ideal and non-ideal prosthesis positioning groups. aLDFA (72–85°) aMPTA (79–90°) PTS (80–94°) c-FCA (-12-17°) s-FCA (0–29°) Ideal(n = 33) Ideal(n = 33) Ideal(n = 29) Ideal(n = 23) Ideal(n = 51) Non-ideal(n = 46) Non-ideal(n = 46) Non-ideal(n = 50) Non-ideal(n = 56) Non-ideal(n = 28) Mean VAS 0.6 ± 0.9 0.8 ± 0.6 0.7 ± 0.7 0.7 ± 0.8 0.7 ± 0.7 0.8 ± 0.8 0.5 ± 0.6 0.8 ± 0.8 0.7 ± 0.6 0.8 ± 0.9 Mean KSS-F 83.4 ± 4.3 83.7 ± 3.3 84.2 ± 3.6 83.1 ± 3.8 84.2 ± 3.5 83.3 ± 3.9 83.7 ± 3.4 83.6 ± 3.9 83.1 ± 3.4 84.5 ± 4.1 Mean KSS-K 83.3 ± 3.9 83.7 ± 3.1 84.2 ± 3.0 83.1 ± 3.7 83.8 ± 3.4 83.4 ± 3.5 84.4 ± 2.8 83.2 ± 3.6 83.4 ± 3.1 83.9 ± 4.0 Mean WOMAC 5.2 ± 3.7 4.8 ± 2.3 4.4 ± 2.4 5.5 ± 3.2 4.6 ± 2.4 5.3 ± 3.2 4.8 ± 2.3 5.1 ± 3.2 5.0 ± 2.4 5.0 ± 3.8 p >0.05 >0.05 >0.05 >0.05 >0.05 Footnotes: Values in parentheses indicate the observed range (minimum–maximum) in this cohort. The values are given as the mean and standard deviation. aLDFA, anatomic lateral distal femoral angle; aMPTA, anatomic medial proximal tibial angle; PTS, posterior tibial slope; c-FCA, coronal femoral component angle; s-FCA, sagittal femoral component angle; VAS, Visual Analog Scale; KSS-F, Knee Society Score – function; KSS-K, Knee Society Score – knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index. Among the included knees, 16 knees (20.3%) showed no PFOA. A total of 49 knees (62.0%) showed mild PFOA (Outerbridge grade 1 to 2), and 14 knees (17.7%) showed moderate to severe PFOA (Outerbridge grade 3 to 4). In the preoperative clinical evaluations, the group without PFOA had significantly better KSS function scores than the group with moderate to severe PFOA (54.0 vs. 50.9, p < 0.001). The group with mild PFOA also had significantly better preoperative KSS function scores compared with the moderate to severe PFOA group (54.3 vs. 50.9, p < 0.001). The mild PFOA group had significantly better preoperative KSS knee scores compared with the moderate to severe PFOA group (55.6 vs. 52.4, p < 0.001). For the preoperative WOMAC scores, there was a significant difference between the no PFOA group and the moderate to severe PFOA group (44.3 vs. 46.8, p < 0.001). For the Kujala score, there were significant differences among all three groups (65.0 vs. 61.9 vs. 54.1, p < 0.001) (Table 2 ). A total of 63 knees showed patellofemoral joint disease. Among them, 41 knees (51.9%) had lesions located in the medial and central region, and 22 knees (27.8%) had lesions located in the lateral region. There were no significant differences in preoperative VAS scores, KSS scores, or WOMAC scores between these two groups (Table 4 ). In terms of postoperative lower limb alignment, 19 knees (24.1%) were categorized into the neutral alignment group (≥ 173° and < 176°) with a mean FTA of 174.2° ± 0.86°. The mild varus group (≥ 176° and < 179°) included 25 knees (31.6%), with a mean FTA of 177.0° ± 0.74°. The moderate varus group (≥ 179° and < 182°) included 23 knees (29.1%), with a mean FTA of 179.8° ± 0.80°. The extreme/out-of-range group (< 173° or ≥ 182°) included 12 knees (15.2%); the valgus subgroup had a mean FTA of 171.8° ± 0.4°, and the severe varus subgroup had a mean FTA of 183.0° ± 1.1°. Preoperative VAS, KSS, WOMAC and Kujala scores showed no significant differences among the four groups (Table 5 ). Postoperative and Preoperative Functional Scores Across Groups To evaluate the improvement of knee function after UKA, we compared the functional scores of all included patients before surgery and at mid-term follow-up after surgery. The results showed that postoperative VAS pain scores, KSS knee scores, KSS function scores, WOMAC scores, and Kujala scores all improved significantly compared with preoperative values (p < 0.001). These findings indicate that UKA can effectively relieve pain and improve knee function and quality of life (Tables 2 , 4 , and 5 ). Severity/Location of Patellofemoral Joint Disease and Postoperative Functional Scores After UKA We found that among patients with different severities of patellofemoral joint disease, there were no significant differences in postoperative KSS scores, WOMAC scores, or Kujala scores between the groups (Table 3 ). There were no significant differences in postoperative VAS, KSS, WOMAC, or Kujala scores between the two groups with different locations of patellofemoral joint disease. The location of patellofemoral joint disease did not have a notable effect on postoperative function after UKA (Table 4 ). Lower Limb Alignment and Postoperative Functional Scores After UKA Based on the FTA, patients were categorized into the neutral alignment group, mild varus group, moderate varus group, and extreme/out-of-range group. Given the small number of valgus and severe varus cases, they were analyzed together as an extreme/out-of-range group to improve the stability of estimates; the two subgroups were not assumed to be biomechanically equivalent. For postoperative KSS function scores, the neutral alignment group showed significantly better results compared with the moderate varus group (84.3 vs. 81.8, p < 0.001) and the extreme/out-of-range group (84.3 vs. 80.7, p < 0.001). The mild varus group also showed significantly better postoperative KSS function scores compared with the moderate varus group (86.1 vs. 81.8, p < 0.001) and the extreme/out-of-range group (86.1 vs. 80.7, p < 0.001). For postoperative KSS knee scores, the extreme/out-of-range group had significantly lower scores compared with the neutral alignment group (80.8 vs. 84.8, p < 0.001) and the mild varus group (80.8 vs. 84.4, p < 0.001). For postoperative WOMAC scores, the neutral alignment group had significantly better results compared with the moderate varus group (4.0 vs. 6.3, p < 0.001) and the extreme/out-of-range group (4.0 vs. 7.8, p < 0.001). The mild varus group also had significantly better postoperative WOMAC scores compared with the moderate varus group (3.2 vs. 6.3, p < 0.001) and the extreme/out-of-range group (3.2 vs. 7.8, p < 0.001). For postoperative Kujala scores, the extreme/out-of-range group also had significantly lower scores compared with the neutral alignment group (82.1 vs. 84.7, p = 0.012) and the mild varus group (82.1 vs. 85.4, p < 0.001). (Table 5 ). Implant Positioning and Postoperative Functional Scores After UKA Based on previous literature, implant positioning parameters were grouped into ideal value and non-ideal value categories. Postoperative functional scores (VAS, KSS, and WOMAC) were compared between the two groups. The results showed that there were no significant differences in postoperative functional scores between the ideal value group and the non-ideal value group for any implant positioning parameter, including aLDFA, aMPTA, PTS, c-FCA, and s-FCA (p > 0.05) (Table 6 ). In this study cohort, most implant positioning values did not fall within the ideal range, but this did not have a significant effect on mid-term postoperative outcomes. Multivariate Analysis To investigate whether the severity of patellofemoral joint disease and lower limb alignment had an interaction effect on postoperative functional outcomes, MANOVA was performed. The results showed that postoperative FTA grouping had a significant main effect on the combined postoperative functional outcomes (Pillai's Trace = 0.406, F = 2.584, p = 0.003, partial η² = 0.135). However, the main effect of PFOA grading (Pillai's Trace = 0.053, F = 0.441, p = 0.895) and the interaction effect between PFOA grading and FTA grouping (Pillai's Trace = 0.376, F = 1.159, p = 0.280) were not significant. Subsequent univariate analysis showed that the main effect of FTA grouping was reflected in KSS function scores (F = 5.788, p = 0.001) and WOMAC scores (F = 7.972, p < 0.001). PFOA grading did not show significant main effects in any postoperative functional score (Fig. 4 ). Complications During mid-term follow-up, none of the 79 UKA cases developed complications such as infection, periprosthetic fracture, implant loosening, polyethylene insert dislocation, or progressive osteoarthritis in the lateral compartment. No revision surgeries were reported for any reason. Three patients reported persistent postoperative pain. Two patients presented with valgus knee but declined further surgery. Three patients received conservative treatment, and one of these patients underwent intra-articular hyaluronic acid injection. Discussion The UKA procedure for medial compartment osteoarthritis of the knee has gradually expanded in clinical practice in China over nearly ten years. However, there are still few studies based on the Chinese population that combine both patient-related factors and surgical technique factors to comprehensively evaluate postoperative clinical outcomes. The main purpose of this study was to analyze the influence of preoperative patellofemoral joint disease severity and location, postoperative lower limb alignment, and implant positioning on mid-term functional outcomes after UKA. Our results are largely in line with existing evidence. Yang[ 4 ] reported that pre-existing PFOA is not necessarily associated with inferior function or reduced survivorship after UKA. Building on this, our study contributes additional evidence by examining a Chinese cohort undergoing Oxford mobile-bearing UKA with mid-term follow-up (~ 5.5 years), applying MRI to delineate both PFOA severity and anatomical distribution, and jointly modeling PFOA, postoperative alignment, and implant positioning, including potential interaction effects. Regarding alignment, Kennedy[ 8 ] found no relationship between postoperative limb alignment and outcomes or revision after Oxford medial UKA. In our cohort, outcomes were similar within the intended alignment range (neutral to mild varus), whereas moderate varus and outlier alignment (valgus or severe varus) were associated with worse patient-reported outcomes. Our study found that Oxford UKA achieved satisfactory outcomes in patients with medial compartment osteoarthritis and significantly improved postoperative knee function. The classical indication for UKA targets isolated tibiofemoral compartment disease, although some researchers have suggested that patellofemoral joint disease should not be considered a contraindication for UKA[ 22 , 23 ]. In China, the prevalence of patellofemoral joint disease is relatively high. In our study, among 79 knees with medial compartment osteoarthritis, 63 knees (79.7%) had varying degrees of patellofemoral joint disease. In the early period of performing Oxford UKA, we took a cautious approach, and each patient underwent MRI to evaluate the condition of the patellofemoral joint and the integrity of the anterior cruciate ligament. Patients with moderate to severe PFOA had worse preoperative KSS function scores, WOMAC scores, and Kujala scores compared with those without PFOA and those with mild PFOA, indicating that PFOA had a negative impact on knee function before surgery. However, after surgery, these three scores showed no significant differences between the groups. In addition, regarding the location of patellofemoral joint disease, there were no significant differences between the medial/central PFOA group and the lateral PFOA group in postoperative KSS, WOMAC, or Kujala scores. This suggests that preoperative PFOA has a limited influence on postoperative outcomes after UKA. Although UKA does not directly address the patellofemoral joint, improving lower limb alignment and joint biomechanics may indirectly reduce patellofemoral joint stress, thereby improving symptoms[ 3 , 24 , 25 ]. Our study further supports the notion that patellofemoral joint disease should not be considered a contraindication for UKA. Accurate restoration of lower limb alignment after surgery is one of the key factors influencing the long-term success of UKA. We found that the neutral alignment group and the mild varus group showed significantly better outcomes in KSS function scores, WOMAC scores and Kujala scores compared with the moderate varus group and the extreme/out-of-range group. Among the three patients who reported persistent postoperative knee pain, two were in the valgus group. Previous biomechanical studies have shown that overcorrection during surgery can increase the load on the non-replaced compartment, which may accelerate cartilage degeneration in that area[ 26 ]. On the other hand, restoring optimal alignment helps maintain dynamic stability throughout knee motion and reduces the risk of subluxation or instability[ 27 ]. Other studies have shown that intraoperative sensor technology can monitor real-time pressure distribution across the implant and provide guidance to optimize alignment and joint balance[ 28 ]. Additionally, abnormal alignment has been shown to alter patellar tracking, which may contribute to anterior knee pain and functional impairment[ 29 ]. If preoperative coronal plane deformity is not adequately corrected, postoperative patellofemoral joint mismatch is more likely to occur[ 30 ]. Our findings further support that controlling postoperative lower limb alignment within neutral or mild varus is associated with better functional outcomes and patient satisfaction. For patients with severe preoperative varus deformity in whom valgus stress radiographs still show persistent varus, UKA should be performed cautiously. Although the alignment-related differences were generally below published minimal clinically important difference (MCID) thresholds[ 31 – 33 ], which can materially change clinical interpretation[ 34 ]. In addition, UKA-specific MCID/PASS thresholds for commonly used PROMs are still evolving and may vary across methods and instruments[ 35 ]. Therefore, our findings are best interpreted as evidence of a robust statistical association. UKA-specific, patient-anchored MCIDs are warranted. In this cohort, valgus and severe varus cases were pooled into a single “extreme/out-of-range” category because each subgroup was small, which would otherwise yield unstable estimates and limited power. This grouping does not imply that valgus and severe varus share the same biomechanics; rather, it was intended to capture substantial deviation from the target postoperative coronal alignment window. Accordingly, our results should be interpreted as a comparison between the target range (neutral to mild varus) and marked deviation, not as evidence of equivalence between valgus and severe varus. Larger studies are warranted to evaluate these extremes separately. We noted that the results of the multivariate analysis showed that, after controlling for PFOA grading, there was a statistically significant overall difference in postoperative functional scores among patients grouped by FTA. At the same time, there was no interaction effect between PFOA grading and FTA grouping. This indicates that the influence of FTA angle on postoperative outcomes is independent and does not depend on the severity of the patient’s PFOA. This study used a new analytical strategy by categorizing implant positioning parameters into an “ideal value group” and a “non-ideal value group” based on previous studies. Although a larger proportion of implants in our cohort were classified into the non-ideal value group, there were no significant differences in postoperative functional scores between the ideal and non-ideal groups. We propose several explanations. First, the mobile bearing design of the Oxford UKA provides a degree of self-adjustment and tolerance, so small deviations in implant positioning may not directly influence postoperative function. Second, the recommended “ideal ranges” reported in the literature may not be universally applicable, as there are substantial individual differences in knee anatomy and biomechanics. For certain patients, even if implant positioning does not fall exactly within the population-based ideal range, mechanical balance and satisfactory functional outcomes may still be achieved at the individual level[ 36 ]. Additionally, the sample size of this study was relatively limited, and the number of cases in the ideal value group was especially small, which may reduce the statistical power to detect subtle differences. Although the mid-term results of this study did not show a significant association between implant positioning and functional outcomes, this does not imply that surgical accuracy can be disregarded. Precise implant positioning remains essential for maintaining joint stability, reducing polyethylene wear and insert dislocation risk, and ensuring long-term implant survival[ 37 – 39 ]. The long-term effects of implant positioning still need to be verified with larger sample sizes and longer follow-up periods in future studies. No revision surgeries were observed during mid-term follow-up; however, three patients required additional conservative treatment due to persistent pain. This suggests that postoperative pain management and individual variability in recovery response should receive careful attention[ 40 , 41 ]. Furthermore, long-term follow-up is important to assess whether abnormal postoperative lower limb alignment may lead to late mechanical failure, indicating the need for extended observation. Based on the current results, we believe that Oxford UKA can significantly improve knee function in patients with medial compartment osteoarthritis. The presence of PFOA before surgery should not be considered a contraindication for UKA. For implant positioning, Oxford UKA demonstrates a certain tolerance for variation and appears to be technically favorable. This study has limitations as it is a retrospective analysis, and selection bias is difficult to avoid. The sample size was relatively limited. Coronal alignment was measured using FTA on short weight-bearing knee radiographs (not long-leg images), and implant positioning was evaluated only on AP/lateral views; therefore, whole-limb alignment and rotational malposition could not be fully accounted for. More precise imaging techniques, such as CT, were not used to assess implant positioning. These limitations indicate that the influence of lower limb alignment and implant positioning on postoperative function should be further examined in studies with larger sample sizes and longer follow-up durations. Conclusion Oxford unicompartmental knee arthroplasty can significantly improve symptoms in patients with medial compartment osteoarthritis of the knee. The severity and location of patellofemoral joint disease, as well as implant positioning, did not show a significant influence on postoperative knee function. Maintaining lower limb alignment in neutral or within 6 degrees of slight varus after surgery may help achieve more satisfactory functional outcomes. Abbreviations 1.UKA - unicompartmental knee arthroplasty 2.TKA- total knee arthroplasty 3.PFOA - patellofemoral joint osteoarthritis 4.MRI - magnetic resonance imaging 5.FTA - femorotibial angle 6.aLDFA - anatomic lateral distal femoral angle 7.aMPTA - anatomic medial proximal tibial angle 8.PTS - posterior tibial slope 9.c-FCA - coronal femoral component angle 10.s-FCA - sagittal femoral component angle 11.VAS - Visual Analog Scale 12.KSS - Knee Society Score 13.WOMAC - Western Ontario and McMaster Universities Osteoarthritis Index 14.ICC - intraclass correlation coefficient 15.MANNOVA - multivariate analysis of variance 16.ANCOVA - analysis of covariance 17.MCID - minimal clinically important difference Declarations Ethics approval the Ethics Committee of the Second Affiliated Hospital of Soochow University (November 13, 2025, Approval number JD-HG-2025-131). All procedures performed in this study were in accordance with the ethical standards of the institutional and/ or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Consent to participate Written informed consent was obtained from individual or guardian participants. Consent for publication Not applicable. Data availability The data supporting the results of this study were sourced from relevant medical institutions, but their availability was limited. These data were used under the permission of this study and thus could not be publicly accessed. However, data could be obtained from the corresponding author at the reasonable request and permission of Second Affiliated Hospital of Soochow University. Competing interests We declare that they have no competing interests. Funding This work was supported by the Suzhou Key Disciplines-Sport Medicine (No. SZXK202506) and the Suzhou key project of Science and Education Strengthening Healthcare (No. ZDXM2024006) Authors' contributions Mingkang Chen and Changqing Zhang carried out the entire procedure including the study design, data extraction, statistical analysis, manuscript writing and editing. Changqing Zhang conceived the study, coordinated and participated in the entire process of drafting and editing the manuscript. Zelin Fan contributed to the data extraction, and statistical analysis. Wei Xu contributed to the study design and data review. All authors have contributed significantly. All authors read and approved the final manuscript. Acknowledgements We would like to give our sincere appreciation to the reviewers for their helpful comments on this article. References Ulrich, G., & Pandit, H. (2023). Current Concepts on Unicompartmental Knee Arthroplasty. Journal of Arthroscopy and Joint Surgery , 11 (1), 1–6. https://doi.org/10.4103/jajs.jajs_65_23 Lu, F., Yan, Y., Wang, W., Zhang, Q., & Guo, W. (2020). Does patellofemoral osteoarthritis affect functional outcomes and survivorship after medial unicompartmental knee arthroplasty? A meta-analysis. Journal of Orthopaedic Surgery and Research , 15 (1). https://doi.org/10.1186/s13018-020-02063-0 Andronic, O., Helmy, N., Kellner, C., & Graf, D. A. (2023). A decreased tibial tuberosity-trochlear groove distance is associated with lateral patellofemoral joint degeneration after implantation of medial fixed-bearing unicompartmental knee arthroplasty — a minimum five year follow-up. International Orthopaedics , 47 (9), 2225–2233. https://doi.org/10.1007/s00264-023-05812-y Yang, J., Li, X., Liu, P., Liu, X., Li, L., & Zhang, M. (2024). The impact of patellofemoral joint diseases on functional outcomes and prosthesis survival in patients undergoing unicompartmental knee arthroplasty: a systematic review and meta-analysis. Journal of Orthopaedic Surgery and Research , 19 (1), 840. https://doi.org/10.1186/s13018-024-05273-y Qing, Z., Ye, J., Ma, J., Li, H., & Wang, Z. (2017). [Application of improved precision alignment method of lower limbs mechanical alignment on open wedge high tibial osteotomy]. Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi . Diquattro, E., Lettner, J., Adriani, M., Prill, R., Salzmann, M., & Becker, R. (2024). High accuracy of component positioning and restoration of lower limb alignment using robotic medial unicompartmental knee arthroplasty. Knee Surgery, Sports Traumatology, Arthroscopy , 33 (6), 1982–1991. https://doi.org/10.1002/ksa.12484 van der List, J. P., Chawla, H., Joskowicz, L., & Pearle, A. D. (2016). Current state of computer navigation and robotics in unicompartmental and total knee arthroplasty: a systematic review with meta‐analysis. Knee Surgery, Sports Traumatology, Arthroscopy , 24 (11), 3482–3495. https://doi.org/10.1007/s00167-016-4305-9 Kennedy, J. A., Molloy, J., Jenkins, C., Mellon, S. J., Dodd, C. A. F., & Murray, D. W. (2019). Functional Outcome and Revision Rate Are Independent of Limb Alignment Following Oxford Medial Unicompartmental Knee Replacement. Journal of Bone and Joint Surgery , 101 (3), 270–275. https://doi.org/10.2106/JBJS.18.00497 Salmani, A., Khani, Y., Shojaei, M., Rashidid, F., Abedi-Azar, R., Darzi Dehkalani, A., … Mehrvar, A. (2025). Preoperative MRI abnormalities are not associated with poor outcomes or altered surgical planning in unicompartmental knee arthroplasty: a systematic review and meta-analysis. European Journal of Orthopaedic Surgery & Traumatology , 35 (1). https://doi.org/10.1007/s00590-025-04490-3 Li, Z., Liu, Q., Zhao, C., Gao, X., Han, W., Stefanik, J. J., … Zhang, Y. (2020). High prevalence of patellofemoral osteoarthritis in China: a multi-center population-based osteoarthritis study. Clinical Rheumatology , 39 (12), 3615–3623. https://doi.org/10.1007/s10067-020-05110-7 Hall, T. A. G., Jones, G. G., & van Arkel, R. J. (2024). Femorotibial angle scan–rescan reproducibility: A high‐precision calculation on a large cohort. Knee Surgery, Sports Traumatology, Arthroscopy , 32 (12), 3133–3140. https://doi.org/10.1002/ksa.12352 Micicoi, L., Machado, A., Ernat, J., Schippers, P., Bernard de Dompsure, R., Bronsard, N., … Micicoi, G. (2023). Restoration of preoperative tibial alignment improves functional results after medial unicompartmental knee arthroplasty. Knee Surgery, Sports Traumatology, Arthroscopy , 31 (11), 5171–5179. https://doi.org/10.1007/s00167-023-07588-5 Morrisey, Z., Cruse, J., Barra, M., Carroll, T., & Drinkwater, C. (2024). Posterior tibial slope considered as an important addition to the CPAK classification system. Journal of Orthopaedics , 51 , 54–59. https://doi.org/10.1016/j.jor.2024.01.008 Sahbat, Y., Gulagaci, F., Mabrouk, A., Karam, K. M., Jacquet, C., Ollivier, M., & Argenson, J.-N. A. (2025). Maintenance of Coronal Alignment and Joint Line Obliquity Has No Effect on Unicompartmental Knee Arthroplasty: Clinical Results at Five Years Follow-Up. The Journal of Arthroplasty , 40 (6), 1508-1515.e1. https://doi.org/10.1016/j.arth.2024.11.041 Slaven, S. E., Cody, J. P., Sershon, R. A., Ho, H., Hopper, R. H., & Fricka, K. B. (2021). Alignment in Medial Fixed-Bearing Unicompartmental Knee Arthroplasty: The Limb Has a Leg Up on the Component. The Journal of Arthroplasty , 36 (12), 3883–3887. https://doi.org/10.1016/j.arth.2021.08.015 Kaya Bicer, E., Servien, E., Lustig, S., Demey, G., Ait Si Selmi, T., & Neyret, P. (2010). Sagittal flexion angle of the femoral component in unicompartmental knee arthroplasty: is it same for both medial and lateral UKAs? Knee Surgery, Sports Traumatology, Arthroscopy , 18 (7), 928–933. https://doi.org/10.1007/s00167-010-1063-y Paley, D. (2002). Principles of Deformity Correction . Berlin, Heidelberg: Springer Berlin Heidelberg. https://doi.org/10.1007/978-3-642-59373-4 Yang, Z., Shen, M., Xie, D., Zhang, J., & Wei, Q. (2024). Correlation between severity of knee joint osteoarthritis and alignment of patellofemoral and patellar height on radiographs. Chinese Medical Journal , 138 (8), 947–952. https://doi.org/10.1097/cm9.0000000000003392 Bodian, C. A., Freedman, G., Hossain, S., Eisenkraft, J. B., & Beilin, Y. (2001). The Visual Analog Scale for Pain. Anesthesiology , 95 (6), 1356–1361. https://doi.org/10.1097/00000542-200112000-00013 Culliton, S. E., Bryant, D. M., MacDonald, S. J., Hibbert, K. M., & Chesworth, B. M. (2018). Validity and Internal Consistency of the New Knee Society Knee Scoring System. Clinical Orthopaedics & Related Research , 476 (1), 77–84. https://doi.org/10.1007/s11999.0000000000000014 Dammerer, D., Liebensteiner, M. C., Kujala, U. M., Emmanuel, K., Kopf, S., Dirisamer, F., & Giesinger, J. M. (2018). Validation of the German version of the Kujala score in patients with patellofemoral instability: a prospective multi-centre study. Archives of Orthopaedic and Trauma Surgery , 138 (4), 527–535. https://doi.org/10.1007/s00402-018-2881-5 Cheng, J., Feng, M., Cao, G., & Lu, S. (2020). Efficacy and mid/long-term survivorship of mobile-bearing unicompartmental knee arthroplasty for medial compartment knee osteoarthritis combined patellofemoral joint arthritis: a prospective cohort study protocol. BMJ Open , 10 (10). https://doi.org/10.1136/bmjopen-2020-038448 Gaggiotti, S., Gaggiotti, S., Ringa, J. C., & Gaggiotti, G. (2024). Associated patellofemoral osteoarthritis is not a contraindication for unicompartmental knee replacement. Report of one hundred ten prostheses with an average 6-year follow-up. Journal of ISAKOS , 9 (4), 549–556. https://doi.org/10.1016/j.jisako.2024.04.003 Kwon, H. M., Lee, J.-A., Koh, Y.-G., Park, K. K., & Kang, K.-T. (2020). Effects of contact stress on patellarfemoral joint and quadriceps force in fixed and mobile-bearing medial unicompartmental knee arthroplasty. Journal of Orthopaedic Surgery and Research , 15 (1). https://doi.org/10.1186/s13018-020-02047-0 Yan, Z., Li, D., Cai, Z., Sun, H., Ma, R., Ma, S., & Xu, J. (2025). A finite element analysis of patellofemoral joint biomechanics: Exploring potential causes of postoperative anterior knee pain following unicompartmental knee arthroplasty. Journal of Orthopaedics , 60 , 58–64. https://doi.org/10.1016/j.jor.2024.08.017 Elliott, J., & Coolican, M. (2021). Biomechanics of Unicompartmental Knee Replacement. Orthopaedic Biomechanics in Sports Medicine , 391–398. https://doi.org/10.1007/978-3-030-81549-3_30 Mortman, R., Gioia, C., Stake, S., Berger, P. Z., Gu, A., Fassihi, S. C., … Argintar, E. H. (2021). Linked kinematic knee balancing in unicompartmental knee arthroplasty. Journal of Orthopaedics , 24 , 182–185. https://doi.org/10.1016/j.jor.2021.02.026 Ge, J., Sun, X., Liu, C., Zhang, Q., Wang, B., & Guo, W. (2023). Intraoperative sensor technology quantifies inter-prosthesis pressure for predicting lower limb alignment after Oxford unicompartmental knee arthroplasty. Frontiers in Bioengineering and Biotechnology , 11 . https://doi.org/10.3389/fbioe.2023.1210713 Yu, Z., Yao, J., Wang, X., Xin, X., Zhang, K., Cai, H., … Yang, B. (2019). Research Methods and Progress of Patellofemoral Joint Kinematics: A Review. Journal of Healthcare Engineering , 2019 , 1–13. https://doi.org/10.1155/2019/9159267 Ruderman, L. V., Bayoumi, T., Burger, J. A., Zuiderbaan, H. A., & Pearle, A. D. (2023). Higher incidence of patellar incongruence after under correction of pre‐arthritic coronal alignment following medial unicompartmental knee arthroplasty. Knee Surgery, Sports Traumatology, Arthroscopy , 31 (12), 5773–5782. https://doi.org/10.1007/s00167-023-07645-z Lizaur-Utrilla, A., Gonzalez-Parreño, S., Martinez-Mendez, D., Miralles-Muñoz, F. A., & Lopez-Prats, F. A. (2019). Minimal clinically important differences and substantial clinical benefits for Knee Society Scores. Knee Surgery, Sports Traumatology, Arthroscopy , 28 (5), 1473–1478. https://doi.org/10.1007/s00167-019-05543-x Qiao, Y., Wu, C., Wu, X., Li, Z., Chen, J., Xu, C., … Zhao, J. (2024). The Value of Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient-Acceptable Symptomatic State for Commonly Used Patient-Reported Outcomes in Recurrent Patellar Instability Patients After Medial Patellofemoral Ligament Reconstruction and Tibial Tubercle Transfer. Arthroscopy: The Journal of Arthroscopic & Related Surgery , 40 (1), 115–123. https://doi.org/10.1016/j.arthro.2023.06.042 Clement, N. D., Bardgett, M., Weir, D., Holland, J., Gerrand, C., & Deehan, D. J. (2018). What is the Minimum Clinically Important Difference for the WOMAC Index After TKA? Clinical Orthopaedics & Related Research , 476 (10), 2005–2014. https://doi.org/10.1097/corr.0000000000000444 Solomito, M. J., Carangelo, R., & Makanji, H. (2025). The Minimal Clinically Important Difference (MCID) for Total Joint Arthroplasty Outcome Measures Varies Substantially by Calculation Method. Journal of Bone and Joint Surgery , 107 (9), 994–999. https://doi.org/10.2106/jbjs.24.00916 Longo, U. G., De Salvatore, S., Candela, V., Berton, A., Casciaro, C., Sciotti, G., … Denaro, V. (2021). Unicompartmental Knee Arthroplasty: Minimal Important Difference and Patient Acceptable Symptom State for the Forgotten Joint Score. Medicina , 57 (4), 324. https://doi.org/10.3390/medicina57040324 Zhang, P., Bai, J., Wang, J., Zhu, C., & Zhou, W. (2023). How to Perform Better on Oxford UKA? A Technical Note from over 500 Surgical Experiences. Orthopaedic Surgery , 15 (9), 2445–2453. https://doi.org/10.1111/os.13811 Rajasekaran, S., Soundarrajan, D., Singh, R., Shiferaw, B. A., Rajasekaran, R. B., Dhanasekararaja, P., & Rajkumar, N. (2024). Comparison of imageless robotic assisted total knee arthroplasty and conventional total knee arthroplasty: early clinical and radiological outcomes of 200 knees. Journal of Robotic Surgery , 18 (1). https://doi.org/10.1007/s11701-024-01905-x Aneja, K., Rudraraju, R. T., & Shyam, A. (2025). Personalized Alignment Strategies and the Need for Customization in Total Knee Arthroplasty: The Role of MISSO Joint Robotic System. Journal of Orthopaedic Case Reports , 15 (8), 1–5. https://doi.org/10.13107/jocr.2025.v15.i08.5862 Rivière, C., Harman, C., Boughton, O., & Cobb, J. (2020). The Kinematic Alignment Technique for Total Knee Arthroplasty. Personalized Hip and Knee Joint Replacement , 175–195. https://doi.org/10.1007/978-3-030-24243-5_16 ten Noever de Brauw, G. V., Aalders, M. B., Kerkhoffs, G. M. M. J., Zuiderbaan, H. A., Keijser, L. C. M., & Benner, J. L. (2024). The mind matters: Psychological factors influence subjective outcomes following unicompartmental knee arthroplasty—A prospective study. Knee Surgery, Sports Traumatology, Arthroscopy , 33 (1), 239–251. https://doi.org/10.1002/ksa.12275 Springborg, A. H., Jensen, C. B., Gromov, K., Troelsen, A., Kehlet, H., & Foss, N. B. (2024). Acute postoperative pain and catastrophizing in unicompartmental knee arthroplasty: a prospective, observational, single-center, cohort study. Regional Anesthesia & Pain Medicine . https://doi.org/10.1136/rapm-2024-105503 Additional Declarations No competing interests reported. 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13:33:45","extension":"html","order_by":36,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":184460,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8496530/v1/40544b4ddc50013687a8af96.html"},{"id":100404196,"identity":"c1c620db-4fe1-412a-877d-dc287b58eb25","added_by":"auto","created_at":"2026-01-16 12:03:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":346695,"visible":true,"origin":"","legend":"\u003cp\u003eRadiographic measurement of femorotibial angle (FTA)\u003c/p\u003e\n\u003cp\u003eFootnotes: A: Preoperative measurement. B: Postoperative measurement.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-8496530/v1/65c0b5c9a191663503eff8aa.png"},{"id":100404374,"identity":"038e13e5-3626-4259-9e94-70ccfba38f91","added_by":"auto","created_at":"2026-01-16 12:03:39","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":397729,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative preoperative and postoperative radiographs.\u003c/p\u003e\n\u003cp\u003eFootnotes: A: preoperative anatomic lateral distal femoral angle (aLDFA), B: preoperative anatomic medial proximal tibial angle (aMPTA), C: preoperative posterior tibial slope (PTS), D: postoperative aLDFA, E: postoperative aMPTA, F: coronal femoral component angle (c-FCA), G: postoperative PTS and sagittal femoral component angle (s-FCA)\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-8496530/v1/f6930688d99b25781ea4597a.png"},{"id":100403917,"identity":"4f1cfb1f-9a6f-4a2e-b7e6-45ebfc21535b","added_by":"auto","created_at":"2026-01-16 12:02:46","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":259728,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative MRI examples demonstrating the Outerbridge classification of patellofemoral joint osteoarthritis (PFOA)\u003c/p\u003e\n\u003cp\u003eFootnotes: Grade I(A): cartilage softening, Grade II(B): fissures smaller than 1.3 cm, Grade III(C): fissures greater than 1.3 cm, Grade IV(D): exposed subchondral bone.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-8496530/v1/34a91b144aa6a982466d5477.png"},{"id":100404357,"identity":"1ec87ff8-bc3e-40ec-af0b-61f998b33671","added_by":"auto","created_at":"2026-01-16 12:03:38","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":53043,"visible":true,"origin":"","legend":"\u003cp\u003eBox plots of postoperative KSS function scores and WOMAC scores across FTA groups.\u003c/p\u003e\n\u003cp\u003eFootnotes: Boxes show medians and interquartile ranges; whiskers represent 1.5×IQR. Multivariate analysis demonstrated a significant main effect of FTA grouping (Pillai's Trace = 0.406, p = 0.003), with univariate effects on KSS (F = 5.788, p = 0.001) and WOMAC (F = 7.972, p \u0026lt; 0.001).\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-8496530/v1/ed9833d6196ba4b687de0693.png"},{"id":100422896,"identity":"774b35da-ba3c-47a9-bd8a-06030c3e9f7e","added_by":"auto","created_at":"2026-01-16 14:12:00","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2542381,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8496530/v1/093cdcd8-9c1b-4324-b35f-587736efd4f2.pdf"},{"id":100403586,"identity":"5c1c7675-a8d4-44be-b314-b1e40da335ac","added_by":"auto","created_at":"2026-01-16 12:02:19","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":100045,"visible":true,"origin":"","legend":"","description":"","filename":"Additionalfile1.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8496530/v1/7eddb239c48c9c4eb7101d58.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eMid-Term Clinical Outcomes of Mobile-Bearing UKA: A Retrospective Study on the Influence of Patellofemoral Joint Disease, Lower Limb Alignment, and Implant Positioning\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eUnicompartmental knee arthroplasty (UKA) has been developed over many years. Many studies have shown that, compared with total knee arthroplasty (TKA), UKA has advantages such as being less invasive, preserving joint position sense, promoting faster recovery, and achieving higher patient satisfaction[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, the indications for UKA are still debated. One major point of controversy is whether patients who have patellofemoral joint osteoarthritis (PFOA) before surgery are suitable candidates for UKA. The study by Lu[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] suggested that patients who have PFOA found during surgery or through preoperative imaging, but who do not show signs of lateral patellofemoral groove involvement, should not be considered contraindicated for UKA. In contrast, the study by Andronic[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] reported that patients with lateral PFOA may have a higher risk of later revision after UKA. A systematic review and meta-analysis by Yang[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] found that preoperative PFOA is generally not linked to inferior function or implant survival after UKA. Nonetheless, heterogeneity in implant type, PFOA assessment, and follow-up persists, and data are still scarce for Oxford mobile-bearing UKA with standardized imaging-based grading of PFOA severity and location in Chinese cohorts.\u003c/p\u003e \u003cp\u003eFor patients, whether choosing UKA or TKA, the accuracy of the surgical technique is an important factor that affects implant survival and functional outcomes. This includes restoring lower limb alignment after surgery and placing the implant in the correct position[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Some researchers believe that improving surgical precision and using computer-assisted technology may help restore alignment and improve the accuracy of implant placement[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. However, Kennedy[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] reported, in a large cohort, that postoperative limb alignment was not associated with functional outcomes or revision risk after Oxford medial UKA. Around 2016, the Oxford UKA technique began to be widely introduced in China, and its clinical use has since expanded. However, there is still a lack of studies in Chinese patients that analyze the effects of lower limb alignment, and implant positioning on the outcomes of UKA. However, the impact of pronounced malalignment outside the target window (e.g., valgus or severe varus outliers) on patient-reported outcomes in routine practice remains unclear, especially when patient- and technique-related factors are assessed concurrently.\u003c/p\u003e \u003cp\u003eAlthough MRI is not routinely recommended as a mandatory imaging modality for preoperative evaluation before Oxford UKA[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], obtaining an ideal lateral radiograph is often challenging, making it difficult to accurately assess the presence of anteromedial osteoarthritis and the integrity of the anterior cruciate ligament. Therefore, magnetic resonance imaging (MRI) was performed in most patients with knee osteoarthritis in our cohort. In addition, patellofemoral joint disease is relatively common in the Chinese population[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], and MRI provides excellent visualization of patellofemoral pathology. In this study, we retrospectively evaluated a Chinese cohort undergoing third-generation Oxford medial UKA to examine the associations of MRI-defined PFOA severity and location, postoperative limb alignment, and implant positioning with mid-term functional outcomes.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatient cohort\u003c/h2\u003e \u003cp\u003eThis study was approved by our institutional ethics committee (Approval Document No. JD-HG-2025-131) and retrospectively reviewed all consecutive patients who underwent cemented third-generation Oxford medial unicompartmental knee arthroplasty at our hospital from May 4, 2017, to December 21, 2020. Eligible cases were identified from institutional surgical records/electronic medical records, and imaging data were retrieved from the picture archiving and communication system. All patients met the surgical indications for medial UKA: patients had medial compartment osteoarthritis with no symptoms in the lateral compartment; flexion contracture was less than 15 degrees, and joint range of motion was preserved; varus deformity was less than 15 degrees and could be passively corrected.\u003c/p\u003e \u003cp\u003eInclusion criteria were patients who underwent UKA due to medial compartment osteoarthritis, with available preoperative MRI and weight-bearing anteroposterior and lateral knee radiographs, as well as postoperative anteroposterior and lateral knee radiographs.\u003c/p\u003e \u003cp\u003eExclusion criteria included imaging data that did not meet study requirements, lateral patellofemoral trochlear groove changes, and secondary osteoarthritis. Anterior knee pain alone was not considered an absolute contraindication. The STROBE flow diagram summarizes the screening process, including the number of excluded cases with specific reasons. The details are further illustrated in an additional figure file [see Additional file 1].\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eData analysis\u003c/h2\u003e \u003cp\u003eTwo orthopedic surgeons evaluated the preoperative and postoperative anteroposterior and lateral knee radiographs, as well as preoperative knee MRI. Preoperative tibiofemoral osteoarthritis severity was graded on weight-bearing anteroposterior knee radiographs using the Kellgren\u0026ndash;Lawrence (K\u0026ndash;L) classification (grades 0\u0026ndash;4). Grading was performed independently by two orthopedic surgeons who were blinded to postoperative outcomes; disagreements were resolved by consensus. The femorotibial angle (FTA) was defined as the lateral angle formed by the anatomical axis of the femur (a line through the center of the femoral medullary canal) and the anatomical axis of the tibia (a line through the center of the tibial medullary canal) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The normal FTA is approximately 173 degrees. The degree of varus was calculated as FTA minus 173 degrees, with positive values indicating varus[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Based on postoperative FTA, patients were categorized into four groups: neutral alignment (\u0026ge;\u0026thinsp;173\u0026deg; and \u0026lt;\u0026thinsp;176\u0026deg;), mild varus (\u0026ge;\u0026thinsp;176\u0026deg; and \u0026lt;\u0026thinsp;179\u0026deg;), moderate varus (\u0026ge;\u0026thinsp;179\u0026deg; and \u0026lt;\u0026thinsp;182\u0026deg;), and an extreme/out-of-range group (\u0026lt;\u0026thinsp;173\u0026deg; or \u0026ge;\u0026thinsp;182\u0026deg;). The extreme/out-of-range group was defined as patients with marked deviation from the intended postoperative alignment window. Because valgus and severe varus outliers were few, they were pooled to improve estimate stability and statistical power, while descriptive results for valgus and severe varus were also presented separately when appropriate. Postoperative anteroposterior and lateral radiographs were used to measure implant positioning parameters, including anatomic lateral distal femoral angle (aLDFA), anatomic medial proximal tibial angle (aMPTA), posterior tibial slope (PTS), coronal femoral component angle (c-FCA), and sagittal femoral component angle (s-FCA) (Figs.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e), based on previously published methods[\u003cspan additionalcitationids=\"CR13 CR14 CR15\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The ideal ranges defined by previous studies and consensus were as follows[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]: aLDFA 79\u0026deg; to 83\u0026deg;, aMPTA 85\u0026deg; to 90\u0026deg;, PTS 83\u0026deg; to 87\u0026deg;, c-FCA \u0026minus;\u0026thinsp;3\u0026deg; to 3\u0026deg;, and s-FCA 0\u0026deg; to 10\u0026deg;. Cases with implant alignment values within these ranges were classified as the \"ideal value group,\" and those outside these ranges were classified as the \"non-ideal value group.\"\u003c/p\u003e \u003cp\u003ePreoperative knee MRI was used to assess the severity and location of patellofemoral joint disease. The Outerbridge classification system was used to evaluate the severity of patellofemoral cartilage damage (grade 0: normal cartilage; grade 1: cartilage softening; grade 2: moderate cartilage fibrillation with fissures less than 1.3 cm; grade 3: severe cartilage fibrillation with fissures greater than 1.3 cm; grade 4: subchondral bone exposure) (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e)[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Patients were classified into three groups: no PFOA (grade 0), mild PFOA (grades 1\u0026ndash;2), and moderate to severe PFOA (grades 3\u0026ndash;4). Based on the location of cartilage damage on the patellofemoral articular surface, patients were further categorized as medial and central PFOA (lesions in the medial two-thirds of the patellofemoral surface) or lateral PFOA (lesions in the lateral one-third). All imaging measurements were performed using AutoCAD 2026.\u003c/p\u003e \u003cp\u003eFunctional evaluations included the Visual Analog Scale (VAS) for pain[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]; the Knee Society Score (KSS), consisting of knee score and function score; the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), which includes pain, stiffness, and daily activity subscales, with higher scores indicating more severe symptoms[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]; and the Kujala score for anterior knee pain, with higher scores indicating better knee function and less pain[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA two-way random-effects model was used to calculate the intraclass correlation coefficient (ICC) to evaluate interobserver and intraobserver reliability. Both interobserver and intraobserver assessments included all patients, and the repeated measurements were performed one week after the initial evaluation. The ICC values for all angle measurements were good (0.75 to 0.90) or excellent (\u0026gt;\u0026thinsp;0.90) (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eIntra-observer and inter-observer reliability of radiographic measurements\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIntra-observer\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eInter-observer\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003cp\u003ePostoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.99(0.98-1.00)\u003c/p\u003e \u003cp\u003e0.98(0.96\u0026ndash;0.99)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.99(0.97\u0026ndash;0.99)\u003c/p\u003e \u003cp\u003e0.97(0.90\u0026ndash;0.96)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eaLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003cp\u003ePostoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.89(0.82\u0026ndash;0.93)\u003c/p\u003e \u003cp\u003e0.86(0.78\u0026ndash;0.90)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.87(0.80\u0026ndash;0.91)\u003c/p\u003e \u003cp\u003e0.84(0.72\u0026ndash;0.89)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eaMPTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003cp\u003ePostoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.91(0.85\u0026ndash;0.95)\u003c/p\u003e \u003cp\u003e0.88(0.86\u0026ndash;0.92)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.94(0.89\u0026ndash;0.97)\u003c/p\u003e \u003cp\u003e0.85(0.78\u0026ndash;0.90)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003cp\u003ePostoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.93(0.88\u0026ndash;0.96)\u003c/p\u003e \u003cp\u003e0.95(0.91\u0026ndash;0.97)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.97(0.90\u0026ndash;0.99)\u003c/p\u003e \u003cp\u003e0.95(0.87\u0026ndash;0.97)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ec-FCA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.90(0.84\u0026ndash;0.94)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.80(0.60\u0026ndash;0.93)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003es-FCA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.92(0.86\u0026ndash;0.96)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.81 (0.72\u0026ndash;0.86)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eFootnotes: Values are intraclass correlation coefficients (ICC) with 95 percent confidence intervals. ICC values of 0.75\u0026ndash;0.90 indicate good reliability, and values above 0.90 indicate excellent reliability.FTA, femorotibial angle; aLDFA, anatomic lateral distal femoral angle; aMPTA, anatomic medial proximal tibial angle; PTS, posterior tibial slope; c-FCA, coronal femoral component angle; s-FCA, sagittal femoral component angle.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical Analysis\u003c/h2\u003e \u003cp\u003e All data were checked by a designated reviewer after entry. Based on the results of the normality test, independent sample t-tests were used for continuous variables with normal distribution, and the Mann\u0026ndash;Whitney U test was used for data with non-normal distribution. Categorical variables were compared using the chi-square test. Multivariate analysis of variance (MANOVA) was used to evaluate the overall effects of PFOA grade, FTA grouping, and their interaction on multiple postoperative functional outcomes, including VAS, KSS, WOMAC, and Kujala scores. For factors showing significant effects in the MANOVA, further analysis was performed using analysis of covariance (ANCOVA) to determine their specific effects on each functional score. A p value of less than 0.05 was considered statistically significant. All statistical analyses were performed using SPSS version 27.0.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003eBaseline characteristics of patients\u003c/h2\u003e \u003cp\u003eA total of 69 eligible patients (79 knees) were included in this study. The average follow-up time was 66.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 months. The mean age at the time of surgery was 62.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0 years. The mean BMI was 25.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4 kg/m\u0026sup2;. The study group consisted of 54 female patients and 15 male patients. Preoperatively, tibiofemoral osteoarthritis was end-stage in nearly all knees: 76/79 (96.2%) were graded as K\u0026ndash;L grade 4, and 3/79 (3.8%) as K\u0026ndash;L grade 3. The distribution of K\u0026ndash;L grades did not differ significantly among groups. Demographic and clinical data were analyzed and compared across groups (Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, \u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, and \u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePatient demographics and baseline characteristics by PFOA severity.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCharacteristic\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall Cohort\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo PFOA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMild PFOA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM/S PFOA\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e49\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDemographics\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e62.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e61.6\u0026thinsp;\u0026plusmn;\u0026thinsp;7.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e% Male(n)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.0(15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.8(3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e12.2(6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e42.9(6)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean BMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e26.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e70.5\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e65.7\u0026thinsp;\u0026plusmn;\u0026thinsp;11.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e64.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePreoperative clinical scores\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean VAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.6\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e50.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e55.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e52.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean WOMAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e45.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e45.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e46.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Kujala\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e61.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e65.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e61.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e54.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePreoperative radiographic c-\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003eharacteristics\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e%K\u0026ndash;L grade IV(n)\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e96.2(76)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100.0(16)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e95.9(47)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e92.9(13)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e180.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e179.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e180.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e179.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean aLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e82.0\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e81.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e82.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e81.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean aMPTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e85.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e85.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e85.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e84.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean PTS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e84.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e84.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eFootnotes: a: The difference was statistically significant compared to the mild PFOA group; b: The difference was statistically significant compared to the moderate-to-severe PFOA group. The values are given as the mean and standard deviation.PFOA, patellofemoral osteoarthritis; M/S PFOA, moderate-to-severe PFOA; BMI, body mass index; VAS, Visual Analog Scale for pain; KSS-F, Knee Society Score \u0026ndash; function; KSS-K, Knee Society Score \u0026ndash; knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePostoperative clinical outcomes by PFOA severity.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eOverall Cohort\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNo PFOA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMild PFOA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eM/S PFOA\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean VAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e83.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e83.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e83.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e82.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e83.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e83.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e83.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e83.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean WOMAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e4.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e4.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Kujala\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e84.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e84.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e \u003cp\u003e84.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c5\"\u003e \u003cp\u003e84.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eFootnotes: There were no statistically significant differences in postoperative functional scores among the three PFOA severity groups (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The values are given as the mean and standard deviation. PFOA, patellofemoral osteoarthritis; M/S PFOA, moderate-to-severe PFOA; VAS, Visual Analog Scale; KSS-F, Knee Society Score \u0026ndash; function; KSS-K, Knee Society Score \u0026ndash; knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical outcomes based on the location of PFOA.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMid-medial PFOA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eLateral PFOA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDemographics\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e62.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.662\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e% Male(n)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19.5(8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.2(4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean BMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.0\u0026thinsp;\u0026plusmn;\u0026thinsp;4.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.158\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e64.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e68.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.031\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e%K\u0026ndash;L grade IV(n)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e95.1(39)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e95.5(21)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePreoperative clinical scores\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean VAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.9\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.193\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e53.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.819\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e55.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.519\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean WOMAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e45.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.084\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Kujala\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e61.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e60.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.237\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePostoperative clinical scores\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean VAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.830\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83.3\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.919\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.680\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean WOMAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.1\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.642\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Kujala\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e84.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e.645\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eFootnotes: Mid-medial PFOA indicates lesions involving the medial and central two-thirds of the patellofemoral articular surface; lateral PFOA indicates lesions located in the lateral one-third. There were no significant differences in postoperative functional outcomes between the two groups (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The values are given as the mean and standard deviation. VAS, Visual Analog Scale; KSS-F, Knee Society Score \u0026ndash; function; KSS-K, Knee Society Score \u0026ndash; knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of clinical outcomes by postoperative lower limb alignment groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNeutral\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMild varus\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eModerate varus\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eExtreme/out-of-range\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eN\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e19\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e23\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e12\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eDemographics\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Age\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.6\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e62.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63.7\u0026thinsp;\u0026plusmn;\u0026thinsp;7.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e62.6\u0026thinsp;\u0026plusmn;\u0026thinsp;6.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e% Male (n)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.8(3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.0(6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e13.0(3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e25.0(3)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean BMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e26.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e26.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e24.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e66.5\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e65.2\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e65.6\u0026thinsp;\u0026plusmn;\u0026thinsp;12.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e71.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e%K\u0026ndash;L grade IV(n)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e94.7(18)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e96.0(24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e95.7(22)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e100.0(12)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePreoperative clinical scores\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean VAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e52.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e53.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e53.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e54.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e54.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e55.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e54.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e54.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean WOMAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e45.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e45.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e45.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Kujala\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60.2\u0026thinsp;\u0026plusmn;\u0026thinsp;4.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e61.6\u0026thinsp;\u0026plusmn;\u0026thinsp;4.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e61.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e60.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003ePostoperative clinical scores\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean VAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e86.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e81.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80.7\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e84.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e80.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean WOMAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7\u003csup\u003eab\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e6.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean Kujala\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e84.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e85.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e84.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e82.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003eFootnotes: a\u0026thinsp;=\u0026thinsp;significantly different compared with the extreme/out-of-range group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05); b\u0026thinsp;=\u0026thinsp;significantly different compared with the moderate varus group (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). The values are given as the mean and standard deviation. The valgus/severe varus group represents an extreme/out-of-range alignment category (\u0026lt;\u0026thinsp;173\u0026deg; or \u0026ge;\u0026thinsp;182\u0026deg;) and does not imply biomechanical equivalence between valgus and severe varus. FTA, femorotibial angle; VAS, Visual Analog Scale; KSS-F, Knee Society Score \u0026ndash; function; KSS-K, Knee Society Score \u0026ndash; knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab6\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 6\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003ePostoperative functional outcome comparison between ideal and non-ideal prosthesis positioning groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eaLDFA\u003c/p\u003e \u003cp\u003e(72\u0026ndash;85\u0026deg;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eaMPTA\u003c/p\u003e \u003cp\u003e(79\u0026ndash;90\u0026deg;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ePTS\u003c/p\u003e \u003cp\u003e(80\u0026ndash;94\u0026deg;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ec-FCA\u003c/p\u003e \u003cp\u003e(-12-17\u0026deg;)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003es-FCA\u003c/p\u003e \u003cp\u003e(0\u0026ndash;29\u0026deg;)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eIdeal(n\u0026thinsp;=\u0026thinsp;33)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eIdeal(n\u0026thinsp;=\u0026thinsp;33)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eIdeal(n\u0026thinsp;=\u0026thinsp;29)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eIdeal(n\u0026thinsp;=\u0026thinsp;23)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eIdeal(n\u0026thinsp;=\u0026thinsp;51)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNon-ideal(n\u0026thinsp;=\u0026thinsp;46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eNon-ideal(n\u0026thinsp;=\u0026thinsp;46)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eNon-ideal(n\u0026thinsp;=\u0026thinsp;50)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eNon-ideal(n\u0026thinsp;=\u0026thinsp;56)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNon-ideal(n\u0026thinsp;=\u0026thinsp;28)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean VAS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.6\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.7\u0026thinsp;\u0026plusmn;\u0026thinsp;0.6\u003c/p\u003e \u003cp\u003e0.8\u0026thinsp;\u0026plusmn;\u0026thinsp;0.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-F\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.3\u003c/p\u003e \u003cp\u003e83.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e84.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003cp\u003e83.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e84.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003cp\u003e83.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e83.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003cp\u003e83.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e83.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003cp\u003e84.5\u0026thinsp;\u0026plusmn;\u0026thinsp;4.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean KSS-K\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e83.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e \u003cp\u003e83.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e84.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003cp\u003e83.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e83.8\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003cp\u003e83.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e84.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.8\u003c/p\u003e \u003cp\u003e83.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e83.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e \u003cp\u003e83.9\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMean WOMAC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e \u003cp\u003e4.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e4.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003cp\u003e5.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e4.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003cp\u003e5.3\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e4.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003cp\u003e5.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ep\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u0026gt;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026gt;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e\u0026gt;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u0026gt;0.05\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eFootnotes: Values in parentheses indicate the observed range (minimum\u0026ndash;maximum) in this cohort. The values are given as the mean and standard deviation. aLDFA, anatomic lateral distal femoral angle; aMPTA, anatomic medial proximal tibial angle; PTS, posterior tibial slope; c-FCA, coronal femoral component angle; s-FCA, sagittal femoral component angle; VAS, Visual Analog Scale; KSS-F, Knee Society Score \u0026ndash; function; KSS-K, Knee Society Score \u0026ndash; knee; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAmong the included knees, 16 knees (20.3%) showed no PFOA. A total of 49 knees (62.0%) showed mild PFOA (Outerbridge grade 1 to 2), and 14 knees (17.7%) showed moderate to severe PFOA (Outerbridge grade 3 to 4). In the preoperative clinical evaluations, the group without PFOA had significantly better KSS function scores than the group with moderate to severe PFOA (54.0 vs. 50.9, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The group with mild PFOA also had significantly better preoperative KSS function scores compared with the moderate to severe PFOA group (54.3 vs. 50.9, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The mild PFOA group had significantly better preoperative KSS knee scores compared with the moderate to severe PFOA group (55.6 vs. 52.4, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). For the preoperative WOMAC scores, there was a significant difference between the no PFOA group and the moderate to severe PFOA group (44.3 vs. 46.8, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). For the Kujala score, there were significant differences among all three groups (65.0 vs. 61.9 vs. 54.1, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). A total of 63 knees showed patellofemoral joint disease. Among them, 41 knees (51.9%) had lesions located in the medial and central region, and 22 knees (27.8%) had lesions located in the lateral region. There were no significant differences in preoperative VAS scores, KSS scores, or WOMAC scores between these two groups (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn terms of postoperative lower limb alignment, 19 knees (24.1%) were categorized into the neutral alignment group (\u0026ge;\u0026thinsp;173\u0026deg; and \u0026lt;\u0026thinsp;176\u0026deg;) with a mean FTA of 174.2\u0026deg; \u0026plusmn; 0.86\u0026deg;. The mild varus group (\u0026ge;\u0026thinsp;176\u0026deg; and \u0026lt;\u0026thinsp;179\u0026deg;) included 25 knees (31.6%), with a mean FTA of 177.0\u0026deg; \u0026plusmn; 0.74\u0026deg;. The moderate varus group (\u0026ge;\u0026thinsp;179\u0026deg; and \u0026lt;\u0026thinsp;182\u0026deg;) included 23 knees (29.1%), with a mean FTA of 179.8\u0026deg; \u0026plusmn; 0.80\u0026deg;. The extreme/out-of-range group (\u0026lt;\u0026thinsp;173\u0026deg; or \u0026ge;\u0026thinsp;182\u0026deg;) included 12 knees (15.2%); the valgus subgroup had a mean FTA of 171.8\u0026deg; \u0026plusmn; 0.4\u0026deg;, and the severe varus subgroup had a mean FTA of 183.0\u0026deg; \u0026plusmn; 1.1\u0026deg;. Preoperative VAS, KSS, WOMAC and Kujala scores showed no significant differences among the four groups (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003ePostoperative and Preoperative Functional Scores Across Groups\u003c/h2\u003e \u003cp\u003eTo evaluate the improvement of knee function after UKA, we compared the functional scores of all included patients before surgery and at mid-term follow-up after surgery. The results showed that postoperative VAS pain scores, KSS knee scores, KSS function scores, WOMAC scores, and Kujala scores all improved significantly compared with preoperative values (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). These findings indicate that UKA can effectively relieve pain and improve knee function and quality of life (Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, and \u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSeverity/Location of Patellofemoral Joint Disease and Postoperative Functional Scores After UKA\u003c/h3\u003e\n\u003cp\u003eWe found that among patients with different severities of patellofemoral joint disease, there were no significant differences in postoperative KSS scores, WOMAC scores, or Kujala scores between the groups (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). There were no significant differences in postoperative VAS, KSS, WOMAC, or Kujala scores between the two groups with different locations of patellofemoral joint disease. The location of patellofemoral joint disease did not have a notable effect on postoperative function after UKA (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eLower Limb Alignment and Postoperative Functional Scores After UKA\u003c/h3\u003e\n\u003cp\u003eBased on the FTA, patients were categorized into the neutral alignment group, mild varus group, moderate varus group, and extreme/out-of-range group. Given the small number of valgus and severe varus cases, they were analyzed together as an extreme/out-of-range group to improve the stability of estimates; the two subgroups were not assumed to be biomechanically equivalent.\u003c/p\u003e \u003cp\u003eFor postoperative KSS function scores, the neutral alignment group showed significantly better results compared with the moderate varus group (84.3 vs. 81.8, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and the extreme/out-of-range group (84.3 vs. 80.7, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The mild varus group also showed significantly better postoperative KSS function scores compared with the moderate varus group (86.1 vs. 81.8, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and the extreme/out-of-range group (86.1 vs. 80.7, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003eFor postoperative KSS knee scores, the extreme/out-of-range group had significantly lower scores compared with the neutral alignment group (80.8 vs. 84.8, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and the mild varus group (80.8 vs. 84.4, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003eFor postoperative WOMAC scores, the neutral alignment group had significantly better results compared with the moderate varus group (4.0 vs. 6.3, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and the extreme/out-of-range group (4.0 vs. 7.8, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The mild varus group also had significantly better postoperative WOMAC scores compared with the moderate varus group (3.2 vs. 6.3, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and the extreme/out-of-range group (3.2 vs. 7.8, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e \u003cp\u003eFor postoperative Kujala scores, the extreme/out-of-range group also had significantly lower scores compared with the neutral alignment group (82.1 vs. 84.7, p\u0026thinsp;=\u0026thinsp;0.012) and the mild varus group (82.1 vs. 85.4, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eImplant Positioning and Postoperative Functional Scores After UKA\u003c/h2\u003e \u003cp\u003eBased on previous literature, implant positioning parameters were grouped into ideal value and non-ideal value categories. Postoperative functional scores (VAS, KSS, and WOMAC) were compared between the two groups. The results showed that there were no significant differences in postoperative functional scores between the ideal value group and the non-ideal value group for any implant positioning parameter, including aLDFA, aMPTA, PTS, c-FCA, and s-FCA (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab6\" class=\"InternalRef\"\u003e6\u003c/span\u003e). In this study cohort, most implant positioning values did not fall within the ideal range, but this did not have a significant effect on mid-term postoperative outcomes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eMultivariate Analysis\u003c/h2\u003e \u003cp\u003eTo investigate whether the severity of patellofemoral joint disease and lower limb alignment had an interaction effect on postoperative functional outcomes, MANOVA was performed. The results showed that postoperative FTA grouping had a significant main effect on the combined postoperative functional outcomes (Pillai's Trace\u0026thinsp;=\u0026thinsp;0.406, F\u0026thinsp;=\u0026thinsp;2.584, p\u0026thinsp;=\u0026thinsp;0.003, partial η\u0026sup2; = 0.135). However, the main effect of PFOA grading (Pillai's Trace\u0026thinsp;=\u0026thinsp;0.053, F\u0026thinsp;=\u0026thinsp;0.441, p\u0026thinsp;=\u0026thinsp;0.895) and the interaction effect between PFOA grading and FTA grouping (Pillai's Trace\u0026thinsp;=\u0026thinsp;0.376, F\u0026thinsp;=\u0026thinsp;1.159, p\u0026thinsp;=\u0026thinsp;0.280) were not significant. Subsequent univariate analysis showed that the main effect of FTA grouping was reflected in KSS function scores (F\u0026thinsp;=\u0026thinsp;5.788, p\u0026thinsp;=\u0026thinsp;0.001) and WOMAC scores (F\u0026thinsp;=\u0026thinsp;7.972, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). PFOA grading did not show significant main effects in any postoperative functional score (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eComplications\u003c/h2\u003e \u003cp\u003eDuring mid-term follow-up, none of the 79 UKA cases developed complications such as infection, periprosthetic fracture, implant loosening, polyethylene insert dislocation, or progressive osteoarthritis in the lateral compartment. No revision surgeries were reported for any reason. Three patients reported persistent postoperative pain. Two patients presented with valgus knee but declined further surgery. Three patients received conservative treatment, and one of these patients underwent intra-articular hyaluronic acid injection.\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe UKA procedure for medial compartment osteoarthritis of the knee has gradually expanded in clinical practice in China over nearly ten years. However, there are still few studies based on the Chinese population that combine both patient-related factors and surgical technique factors to comprehensively evaluate postoperative clinical outcomes. The main purpose of this study was to analyze the influence of preoperative patellofemoral joint disease severity and location, postoperative lower limb alignment, and implant positioning on mid-term functional outcomes after UKA.\u003c/p\u003e \u003cp\u003eOur results are largely in line with existing evidence. Yang[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] reported that pre-existing PFOA is not necessarily associated with inferior function or reduced survivorship after UKA. Building on this, our study contributes additional evidence by examining a Chinese cohort undergoing Oxford mobile-bearing UKA with mid-term follow-up (~\u0026thinsp;5.5 years), applying MRI to delineate both PFOA severity and anatomical distribution, and jointly modeling PFOA, postoperative alignment, and implant positioning, including potential interaction effects. Regarding alignment, Kennedy[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] found no relationship between postoperative limb alignment and outcomes or revision after Oxford medial UKA. In our cohort, outcomes were similar within the intended alignment range (neutral to mild varus), whereas moderate varus and outlier alignment (valgus or severe varus) were associated with worse patient-reported outcomes.\u003c/p\u003e \u003cp\u003eOur study found that Oxford UKA achieved satisfactory outcomes in patients with medial compartment osteoarthritis and significantly improved postoperative knee function. The classical indication for UKA targets isolated tibiofemoral compartment disease, although some researchers have suggested that patellofemoral joint disease should not be considered a contraindication for UKA[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. In China, the prevalence of patellofemoral joint disease is relatively high. In our study, among 79 knees with medial compartment osteoarthritis, 63 knees (79.7%) had varying degrees of patellofemoral joint disease. In the early period of performing Oxford UKA, we took a cautious approach, and each patient underwent MRI to evaluate the condition of the patellofemoral joint and the integrity of the anterior cruciate ligament. Patients with moderate to severe PFOA had worse preoperative KSS function scores, WOMAC scores, and Kujala scores compared with those without PFOA and those with mild PFOA, indicating that PFOA had a negative impact on knee function before surgery. However, after surgery, these three scores showed no significant differences between the groups. In addition, regarding the location of patellofemoral joint disease, there were no significant differences between the medial/central PFOA group and the lateral PFOA group in postoperative KSS, WOMAC, or Kujala scores. This suggests that preoperative PFOA has a limited influence on postoperative outcomes after UKA. Although UKA does not directly address the patellofemoral joint, improving lower limb alignment and joint biomechanics may indirectly reduce patellofemoral joint stress, thereby improving symptoms[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Our study further supports the notion that patellofemoral joint disease should not be considered a contraindication for UKA.\u003c/p\u003e \u003cp\u003eAccurate restoration of lower limb alignment after surgery is one of the key factors influencing the long-term success of UKA. We found that the neutral alignment group and the mild varus group showed significantly better outcomes in KSS function scores, WOMAC scores and Kujala scores compared with the moderate varus group and the extreme/out-of-range group. Among the three patients who reported persistent postoperative knee pain, two were in the valgus group. Previous biomechanical studies have shown that overcorrection during surgery can increase the load on the non-replaced compartment, which may accelerate cartilage degeneration in that area[\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. On the other hand, restoring optimal alignment helps maintain dynamic stability throughout knee motion and reduces the risk of subluxation or instability[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Other studies have shown that intraoperative sensor technology can monitor real-time pressure distribution across the implant and provide guidance to optimize alignment and joint balance[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. Additionally, abnormal alignment has been shown to alter patellar tracking, which may contribute to anterior knee pain and functional impairment[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. If preoperative coronal plane deformity is not adequately corrected, postoperative patellofemoral joint mismatch is more likely to occur[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Our findings further support that controlling postoperative lower limb alignment within neutral or mild varus is associated with better functional outcomes and patient satisfaction. For patients with severe preoperative varus deformity in whom valgus stress radiographs still show persistent varus, UKA should be performed cautiously.\u003c/p\u003e \u003cp\u003eAlthough the alignment-related differences were generally below published minimal clinically important difference (MCID) thresholds[\u003cspan additionalcitationids=\"CR32\" citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e], which can materially change clinical interpretation[\u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e]. In addition, UKA-specific MCID/PASS thresholds for commonly used PROMs are still evolving and may vary across methods and instruments[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. Therefore, our findings are best interpreted as evidence of a robust statistical association. UKA-specific, patient-anchored MCIDs are warranted.\u003c/p\u003e \u003cp\u003eIn this cohort, valgus and severe varus cases were pooled into a single \u0026ldquo;extreme/out-of-range\u0026rdquo; category because each subgroup was small, which would otherwise yield unstable estimates and limited power. This grouping does not imply that valgus and severe varus share the same biomechanics; rather, it was intended to capture substantial deviation from the target postoperative coronal alignment window. Accordingly, our results should be interpreted as a comparison between the target range (neutral to mild varus) and marked deviation, not as evidence of equivalence between valgus and severe varus. Larger studies are warranted to evaluate these extremes separately.\u003c/p\u003e \u003cp\u003eWe noted that the results of the multivariate analysis showed that, after controlling for PFOA grading, there was a statistically significant overall difference in postoperative functional scores among patients grouped by FTA. At the same time, there was no interaction effect between PFOA grading and FTA grouping. This indicates that the influence of FTA angle on postoperative outcomes is independent and does not depend on the severity of the patient\u0026rsquo;s PFOA.\u003c/p\u003e \u003cp\u003eThis study used a new analytical strategy by categorizing implant positioning parameters into an \u0026ldquo;ideal value group\u0026rdquo; and a \u0026ldquo;non-ideal value group\u0026rdquo; based on previous studies. Although a larger proportion of implants in our cohort were classified into the non-ideal value group, there were no significant differences in postoperative functional scores between the ideal and non-ideal groups. We propose several explanations. First, the mobile bearing design of the Oxford UKA provides a degree of self-adjustment and tolerance, so small deviations in implant positioning may not directly influence postoperative function. Second, the recommended \u0026ldquo;ideal ranges\u0026rdquo; reported in the literature may not be universally applicable, as there are substantial individual differences in knee anatomy and biomechanics. For certain patients, even if implant positioning does not fall exactly within the population-based ideal range, mechanical balance and satisfactory functional outcomes may still be achieved at the individual level[\u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]. Additionally, the sample size of this study was relatively limited, and the number of cases in the ideal value group was especially small, which may reduce the statistical power to detect subtle differences. Although the mid-term results of this study did not show a significant association between implant positioning and functional outcomes, this does not imply that surgical accuracy can be disregarded. Precise implant positioning remains essential for maintaining joint stability, reducing polyethylene wear and insert dislocation risk, and ensuring long-term implant survival[\u003cspan additionalcitationids=\"CR38\" citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e]. The long-term effects of implant positioning still need to be verified with larger sample sizes and longer follow-up periods in future studies.\u003c/p\u003e \u003cp\u003eNo revision surgeries were observed during mid-term follow-up; however, three patients required additional conservative treatment due to persistent pain. This suggests that postoperative pain management and individual variability in recovery response should receive careful attention[\u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e]. Furthermore, long-term follow-up is important to assess whether abnormal postoperative lower limb alignment may lead to late mechanical failure, indicating the need for extended observation.\u003c/p\u003e \u003cp\u003eBased on the current results, we believe that Oxford UKA can significantly improve knee function in patients with medial compartment osteoarthritis. The presence of PFOA before surgery should not be considered a contraindication for UKA. For implant positioning, Oxford UKA demonstrates a certain tolerance for variation and appears to be technically favorable.\u003c/p\u003e \u003cp\u003eThis study has limitations as it is a retrospective analysis, and selection bias is difficult to avoid. The sample size was relatively limited. Coronal alignment was measured using FTA on short weight-bearing knee radiographs (not long-leg images), and implant positioning was evaluated only on AP/lateral views; therefore, whole-limb alignment and rotational malposition could not be fully accounted for. More precise imaging techniques, such as CT, were not used to assess implant positioning. These limitations indicate that the influence of lower limb alignment and implant positioning on postoperative function should be further examined in studies with larger sample sizes and longer follow-up durations.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eOxford unicompartmental knee arthroplasty can significantly improve symptoms in patients with medial compartment osteoarthritis of the knee. The severity and location of patellofemoral joint disease, as well as implant positioning, did not show a significant influence on postoperative knee function. Maintaining lower limb alignment in neutral or within 6 degrees of slight varus after surgery may help achieve more satisfactory functional outcomes.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e1.UKA - unicompartmental knee arthroplasty\u003c/p\u003e\n\u003cp\u003e2.TKA- total knee arthroplasty\u003c/p\u003e\n\u003cp\u003e3.PFOA - patellofemoral joint osteoarthritis\u003c/p\u003e\n\u003cp\u003e4.MRI - magnetic resonance imaging\u003c/p\u003e\n\u003cp\u003e5.FTA - femorotibial angle\u003c/p\u003e\n\u003cp\u003e6.aLDFA - anatomic lateral distal femoral angle\u003c/p\u003e\n\u003cp\u003e7.aMPTA - anatomic medial proximal tibial angle\u003c/p\u003e\n\u003cp\u003e8.PTS - posterior tibial slope\u003c/p\u003e\n\u003cp\u003e9.c-FCA - coronal femoral component angle\u003c/p\u003e\n\u003cp\u003e10.s-FCA - sagittal femoral component angle\u003c/p\u003e\n\u003cp\u003e11.VAS - Visual Analog Scale\u003c/p\u003e\n\u003cp\u003e12.KSS - Knee Society Score\u003c/p\u003e\n\u003cp\u003e13.WOMAC - Western Ontario and McMaster Universities Osteoarthritis Index\u003c/p\u003e\n\u003cp\u003e14.ICC - intraclass correlation coefficient\u003c/p\u003e\n\u003cp\u003e15.MANNOVA - multivariate analysis of variance\u003c/p\u003e\n\u003cp\u003e16.ANCOVA - analysis of covariance\u003c/p\u003e\n\u003cp\u003e17.MCID - minimal clinically important difference\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ethe Ethics Committee of the Second Affiliated Hospital of Soochow University (November 13, 2025, Approval number JD-HG-2025-131). All procedures performed in this study were in accordance with the ethical standards of the institutional and/ or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from individual or guardian participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data supporting the results of this study were sourced from relevant medical institutions, but their availability was limited. These data were used under the permission of this study and thus could not be publicly accessed. However, data could be obtained from the corresponding author at the reasonable request and permission of Second Affiliated Hospital of Soochow University.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Suzhou Key Disciplines-Sport Medicine (No. SZXK202506) and the Suzhou key project of Science and Education Strengthening Healthcare (No. ZDXM2024006)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMingkang Chen and Changqing Zhang carried out the entire procedure including the study design, data extraction, statistical analysis, manuscript writing and editing. Changqing Zhang conceived the study, coordinated and participated in the entire process of drafting and editing the manuscript. Zelin Fan contributed to the data extraction, and statistical analysis. Wei Xu contributed to the study design and data review. All authors have contributed significantly. All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to give our sincere appreciation to the reviewers for their helpful comments on this article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eUlrich, G., \u0026amp; Pandit, H. (2023). Current Concepts on Unicompartmental Knee Arthroplasty. \u003cem\u003eJournal of Arthroscopy and Joint Surgery\u003c/em\u003e, \u003cem\u003e11\u003c/em\u003e(1), 1\u0026ndash;6. https://doi.org/10.4103/jajs.jajs_65_23\u003c/li\u003e\n\u003cli\u003eLu, F., Yan, Y., Wang, W., Zhang, Q., \u0026amp; Guo, W. (2020). Does patellofemoral osteoarthritis affect functional outcomes and survivorship after medial unicompartmental knee arthroplasty? A meta-analysis. \u003cem\u003eJournal of Orthopaedic Surgery and Research\u003c/em\u003e, \u003cem\u003e15\u003c/em\u003e(1). https://doi.org/10.1186/s13018-020-02063-0\u003c/li\u003e\n\u003cli\u003eAndronic, O., Helmy, N., Kellner, C., \u0026amp; Graf, D. A. (2023). A decreased tibial tuberosity-trochlear groove distance is associated with lateral patellofemoral joint degeneration after implantation of medial fixed-bearing unicompartmental knee arthroplasty \u0026mdash; a minimum five year follow-up. \u003cem\u003eInternational Orthopaedics\u003c/em\u003e, \u003cem\u003e47\u003c/em\u003e(9), 2225\u0026ndash;2233. https://doi.org/10.1007/s00264-023-05812-y\u003c/li\u003e\n\u003cli\u003eYang, J., Li, X., Liu, P., Liu, X., Li, L., \u0026amp; Zhang, M. (2024). The impact of patellofemoral joint diseases on functional outcomes and prosthesis survival in patients undergoing unicompartmental knee arthroplasty: a systematic review and meta-analysis. \u003cem\u003eJournal of Orthopaedic Surgery and Research\u003c/em\u003e, \u003cem\u003e19\u003c/em\u003e(1), 840. https://doi.org/10.1186/s13018-024-05273-y\u003c/li\u003e\n\u003cli\u003eQing, Z., Ye, J., Ma, J., Li, H., \u0026amp; Wang, Z. (2017). [Application of improved precision alignment method of lower limbs mechanical alignment on open wedge high tibial osteotomy]. \u003cem\u003eZhongguo Xiu Fu Chong Jian Wai Ke Za Zhi\u003c/em\u003e.\u003c/li\u003e\n\u003cli\u003eDiquattro, E., Lettner, J., Adriani, M., Prill, R., Salzmann, M., \u0026amp; Becker, R. (2024). High accuracy of component positioning and restoration of lower limb alignment using robotic medial unicompartmental knee arthroplasty. \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e33\u003c/em\u003e(6), 1982\u0026ndash;1991. https://doi.org/10.1002/ksa.12484\u003c/li\u003e\n\u003cli\u003evan der List, J. P., Chawla, H., Joskowicz, L., \u0026amp; Pearle, A. D. (2016). Current state of computer navigation and robotics in unicompartmental and total knee arthroplasty: a systematic review with meta‐analysis. \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e24\u003c/em\u003e(11), 3482\u0026ndash;3495. https://doi.org/10.1007/s00167-016-4305-9\u003c/li\u003e\n\u003cli\u003eKennedy, J. A., Molloy, J., Jenkins, C., Mellon, S. J., Dodd, C. A. F., \u0026amp; Murray, D. W. (2019). Functional Outcome and Revision Rate Are Independent of Limb Alignment Following Oxford Medial Unicompartmental Knee Replacement. \u003cem\u003eJournal of Bone and Joint Surgery\u003c/em\u003e, \u003cem\u003e101\u003c/em\u003e(3), 270\u0026ndash;275. https://doi.org/10.2106/JBJS.18.00497\u003c/li\u003e\n\u003cli\u003eSalmani, A., Khani, Y., Shojaei, M., Rashidid, F., Abedi-Azar, R., Darzi Dehkalani, A., \u0026hellip; Mehrvar, A. (2025). Preoperative MRI abnormalities are not associated with poor outcomes or altered surgical planning in unicompartmental knee arthroplasty: a systematic review and meta-analysis. \u003cem\u003eEuropean Journal of Orthopaedic Surgery \u0026amp;amp; Traumatology\u003c/em\u003e, \u003cem\u003e35\u003c/em\u003e(1). https://doi.org/10.1007/s00590-025-04490-3\u003c/li\u003e\n\u003cli\u003eLi, Z., Liu, Q., Zhao, C., Gao, X., Han, W., Stefanik, J. J., \u0026hellip; Zhang, Y. (2020). High prevalence of patellofemoral osteoarthritis in China: a multi-center population-based osteoarthritis study. \u003cem\u003eClinical Rheumatology\u003c/em\u003e, \u003cem\u003e39\u003c/em\u003e(12), 3615\u0026ndash;3623. https://doi.org/10.1007/s10067-020-05110-7\u003c/li\u003e\n\u003cli\u003eHall, T. A. G., Jones, G. G., \u0026amp; van Arkel, R. J. (2024). Femorotibial angle scan\u0026ndash;rescan reproducibility: A high‐precision calculation on a large cohort. \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e32\u003c/em\u003e(12), 3133\u0026ndash;3140. https://doi.org/10.1002/ksa.12352\u003c/li\u003e\n\u003cli\u003eMicicoi, L., Machado, A., Ernat, J., Schippers, P., Bernard de Dompsure, R., Bronsard, N., \u0026hellip; Micicoi, G. (2023). Restoration of preoperative tibial alignment improves functional results after medial unicompartmental knee arthroplasty. \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e31\u003c/em\u003e(11), 5171\u0026ndash;5179. https://doi.org/10.1007/s00167-023-07588-5\u003c/li\u003e\n\u003cli\u003eMorrisey, Z., Cruse, J., Barra, M., Carroll, T., \u0026amp; Drinkwater, C. (2024). Posterior tibial slope considered as an important addition to the CPAK classification system. \u003cem\u003eJournal of Orthopaedics\u003c/em\u003e, \u003cem\u003e51\u003c/em\u003e, 54\u0026ndash;59. https://doi.org/10.1016/j.jor.2024.01.008\u003c/li\u003e\n\u003cli\u003eSahbat, Y., Gulagaci, F., Mabrouk, A., Karam, K. M., Jacquet, C., Ollivier, M., \u0026amp; Argenson, J.-N. A. (2025). Maintenance of Coronal Alignment and Joint Line Obliquity Has No Effect on Unicompartmental Knee Arthroplasty: Clinical Results at Five Years Follow-Up. \u003cem\u003eThe Journal of Arthroplasty\u003c/em\u003e, \u003cem\u003e40\u003c/em\u003e(6), 1508-1515.e1. https://doi.org/10.1016/j.arth.2024.11.041\u003c/li\u003e\n\u003cli\u003eSlaven, S. E., Cody, J. P., Sershon, R. A., Ho, H., Hopper, R. H., \u0026amp; Fricka, K. B. (2021). Alignment in Medial Fixed-Bearing Unicompartmental Knee Arthroplasty: The Limb Has a Leg Up on the Component. \u003cem\u003eThe Journal of Arthroplasty\u003c/em\u003e, \u003cem\u003e36\u003c/em\u003e(12), 3883\u0026ndash;3887. https://doi.org/10.1016/j.arth.2021.08.015\u003c/li\u003e\n\u003cli\u003eKaya Bicer, E., Servien, E., Lustig, S., Demey, G., Ait Si Selmi, T., \u0026amp; Neyret, P. (2010). Sagittal flexion angle of the femoral component in unicompartmental knee arthroplasty: is it same for both medial and lateral UKAs? \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e18\u003c/em\u003e(7), 928\u0026ndash;933. https://doi.org/10.1007/s00167-010-1063-y\u003c/li\u003e\n\u003cli\u003ePaley, D. (2002). \u003cem\u003ePrinciples of Deformity Correction\u003c/em\u003e. Berlin, Heidelberg: Springer Berlin Heidelberg. https://doi.org/10.1007/978-3-642-59373-4\u003c/li\u003e\n\u003cli\u003eYang, Z., Shen, M., Xie, D., Zhang, J., \u0026amp; Wei, Q. (2024). Correlation between severity of knee joint osteoarthritis and alignment of patellofemoral and patellar height on radiographs. \u003cem\u003eChinese Medical Journal\u003c/em\u003e, \u003cem\u003e138\u003c/em\u003e(8), 947\u0026ndash;952. https://doi.org/10.1097/cm9.0000000000003392\u003c/li\u003e\n\u003cli\u003eBodian, C. A., Freedman, G., Hossain, S., Eisenkraft, J. B., \u0026amp; Beilin, Y. (2001). The Visual Analog Scale for Pain. \u003cem\u003eAnesthesiology\u003c/em\u003e, \u003cem\u003e95\u003c/em\u003e(6), 1356\u0026ndash;1361. https://doi.org/10.1097/00000542-200112000-00013\u003c/li\u003e\n\u003cli\u003eCulliton, S. E., Bryant, D. M., MacDonald, S. J., Hibbert, K. M., \u0026amp; Chesworth, B. M. (2018). Validity and Internal Consistency of the New Knee Society Knee Scoring System. \u003cem\u003eClinical Orthopaedics \u0026amp;amp; Related Research\u003c/em\u003e, \u003cem\u003e476\u003c/em\u003e(1), 77\u0026ndash;84. https://doi.org/10.1007/s11999.0000000000000014\u003c/li\u003e\n\u003cli\u003eDammerer, D., Liebensteiner, M. C., Kujala, U. M., Emmanuel, K., Kopf, S., Dirisamer, F., \u0026amp; Giesinger, J. M. (2018). Validation of the German version of the Kujala score in patients with patellofemoral instability: a prospective multi-centre study. \u003cem\u003eArchives of Orthopaedic and Trauma Surgery\u003c/em\u003e, \u003cem\u003e138\u003c/em\u003e(4), 527\u0026ndash;535. https://doi.org/10.1007/s00402-018-2881-5\u003c/li\u003e\n\u003cli\u003eCheng, J., Feng, M., Cao, G., \u0026amp; Lu, S. (2020). Efficacy and mid/long-term survivorship of mobile-bearing unicompartmental knee arthroplasty for medial compartment knee osteoarthritis combined patellofemoral joint arthritis: a prospective cohort study protocol. \u003cem\u003eBMJ Open\u003c/em\u003e, \u003cem\u003e10\u003c/em\u003e(10). https://doi.org/10.1136/bmjopen-2020-038448\u003c/li\u003e\n\u003cli\u003eGaggiotti, S., Gaggiotti, S., Ringa, J. C., \u0026amp; Gaggiotti, G. (2024). Associated patellofemoral osteoarthritis is not a contraindication for unicompartmental knee replacement. Report of one hundred ten prostheses with an average 6-year follow-up. \u003cem\u003eJournal of ISAKOS\u003c/em\u003e, \u003cem\u003e9\u003c/em\u003e(4), 549\u0026ndash;556. https://doi.org/10.1016/j.jisako.2024.04.003\u003c/li\u003e\n\u003cli\u003eKwon, H. M., Lee, J.-A., Koh, Y.-G., Park, K. K., \u0026amp; Kang, K.-T. (2020). Effects of contact stress on patellarfemoral joint and quadriceps force in fixed and mobile-bearing medial unicompartmental knee arthroplasty. \u003cem\u003eJournal of Orthopaedic Surgery and Research\u003c/em\u003e, \u003cem\u003e15\u003c/em\u003e(1). https://doi.org/10.1186/s13018-020-02047-0\u003c/li\u003e\n\u003cli\u003eYan, Z., Li, D., Cai, Z., Sun, H., Ma, R., Ma, S., \u0026amp; Xu, J. (2025). A finite element analysis of patellofemoral joint biomechanics: Exploring potential causes of postoperative anterior knee pain following unicompartmental knee arthroplasty. \u003cem\u003eJournal of Orthopaedics\u003c/em\u003e, \u003cem\u003e60\u003c/em\u003e, 58\u0026ndash;64. https://doi.org/10.1016/j.jor.2024.08.017\u003c/li\u003e\n\u003cli\u003eElliott, J., \u0026amp; Coolican, M. (2021). Biomechanics of Unicompartmental Knee Replacement. \u003cem\u003eOrthopaedic Biomechanics in Sports Medicine\u003c/em\u003e, 391\u0026ndash;398. https://doi.org/10.1007/978-3-030-81549-3_30\u003c/li\u003e\n\u003cli\u003eMortman, R., Gioia, C., Stake, S., Berger, P. Z., Gu, A., Fassihi, S. C., \u0026hellip; Argintar, E. H. (2021). Linked kinematic knee balancing in unicompartmental knee arthroplasty. \u003cem\u003eJournal of Orthopaedics\u003c/em\u003e, \u003cem\u003e24\u003c/em\u003e, 182\u0026ndash;185. https://doi.org/10.1016/j.jor.2021.02.026\u003c/li\u003e\n\u003cli\u003eGe, J., Sun, X., Liu, C., Zhang, Q., Wang, B., \u0026amp; Guo, W. (2023). Intraoperative sensor technology quantifies inter-prosthesis pressure for predicting lower limb alignment after Oxford unicompartmental knee arthroplasty. \u003cem\u003eFrontiers in Bioengineering and Biotechnology\u003c/em\u003e, \u003cem\u003e11\u003c/em\u003e. https://doi.org/10.3389/fbioe.2023.1210713\u003c/li\u003e\n\u003cli\u003eYu, Z., Yao, J., Wang, X., Xin, X., Zhang, K., Cai, H., \u0026hellip; Yang, B. (2019). Research Methods and Progress of Patellofemoral Joint Kinematics: A Review. \u003cem\u003eJournal of Healthcare Engineering\u003c/em\u003e, \u003cem\u003e2019\u003c/em\u003e, 1\u0026ndash;13. https://doi.org/10.1155/2019/9159267\u003c/li\u003e\n\u003cli\u003eRuderman, L. V., Bayoumi, T., Burger, J. A., Zuiderbaan, H. A., \u0026amp; Pearle, A. D. (2023). Higher incidence of patellar incongruence after under correction of pre‐arthritic coronal alignment following medial unicompartmental knee arthroplasty. \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e31\u003c/em\u003e(12), 5773\u0026ndash;5782. https://doi.org/10.1007/s00167-023-07645-z\u003c/li\u003e\n\u003cli\u003eLizaur-Utrilla, A., Gonzalez-Parre\u0026ntilde;o, S., Martinez-Mendez, D., Miralles-Mu\u0026ntilde;oz, F. A., \u0026amp; Lopez-Prats, F. A. (2019). Minimal clinically important differences and substantial clinical benefits for Knee Society Scores. \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e28\u003c/em\u003e(5), 1473\u0026ndash;1478. https://doi.org/10.1007/s00167-019-05543-x\u003c/li\u003e\n\u003cli\u003eQiao, Y., Wu, C., Wu, X., Li, Z., Chen, J., Xu, C., \u0026hellip; Zhao, J. (2024). The Value of Minimal Clinically Important Difference, Substantial Clinical Benefit, and Patient-Acceptable Symptomatic State for Commonly Used Patient-Reported Outcomes in Recurrent Patellar Instability Patients After Medial Patellofemoral Ligament Reconstruction and Tibial Tubercle Transfer. \u003cem\u003eArthroscopy: The Journal of Arthroscopic \u0026amp; Related Surgery\u003c/em\u003e, \u003cem\u003e40\u003c/em\u003e(1), 115\u0026ndash;123. https://doi.org/10.1016/j.arthro.2023.06.042\u003c/li\u003e\n\u003cli\u003eClement, N. D., Bardgett, M., Weir, D., Holland, J., Gerrand, C., \u0026amp; Deehan, D. J. (2018). What is the Minimum Clinically Important Difference for the WOMAC Index After TKA? \u003cem\u003eClinical Orthopaedics \u0026amp;amp; Related Research\u003c/em\u003e, \u003cem\u003e476\u003c/em\u003e(10), 2005\u0026ndash;2014. https://doi.org/10.1097/corr.0000000000000444\u003c/li\u003e\n\u003cli\u003eSolomito, M. J., Carangelo, R., \u0026amp; Makanji, H. (2025). The Minimal Clinically Important Difference (MCID) for Total Joint Arthroplasty Outcome Measures Varies Substantially by Calculation Method. \u003cem\u003eJournal of Bone and Joint Surgery\u003c/em\u003e, \u003cem\u003e107\u003c/em\u003e(9), 994\u0026ndash;999. https://doi.org/10.2106/jbjs.24.00916\u003c/li\u003e\n\u003cli\u003eLongo, U. G., De Salvatore, S., Candela, V., Berton, A., Casciaro, C., Sciotti, G., \u0026hellip; Denaro, V. (2021). Unicompartmental Knee Arthroplasty: Minimal Important Difference and Patient Acceptable Symptom State for the Forgotten Joint Score. \u003cem\u003eMedicina\u003c/em\u003e, \u003cem\u003e57\u003c/em\u003e(4), 324. https://doi.org/10.3390/medicina57040324\u003c/li\u003e\n\u003cli\u003eZhang, P., Bai, J., Wang, J., Zhu, C., \u0026amp; Zhou, W. (2023). How to Perform Better on Oxford \u0026lt;scp\u0026gt;UKA\u0026lt;/scp\u0026gt;? A Technical Note from over 500 Surgical Experiences. \u003cem\u003eOrthopaedic Surgery\u003c/em\u003e, \u003cem\u003e15\u003c/em\u003e(9), 2445\u0026ndash;2453. https://doi.org/10.1111/os.13811\u003c/li\u003e\n\u003cli\u003eRajasekaran, S., Soundarrajan, D., Singh, R., Shiferaw, B. A., Rajasekaran, R. B., Dhanasekararaja, P., \u0026amp; Rajkumar, N. (2024). Comparison of imageless robotic assisted total knee arthroplasty and conventional total knee arthroplasty: early clinical and radiological outcomes of 200 knees. \u003cem\u003eJournal of Robotic Surgery\u003c/em\u003e, \u003cem\u003e18\u003c/em\u003e(1). https://doi.org/10.1007/s11701-024-01905-x\u003c/li\u003e\n\u003cli\u003eAneja, K., Rudraraju, R. T., \u0026amp; Shyam, A. (2025). Personalized Alignment Strategies and the Need for Customization in Total Knee Arthroplasty: The Role of MISSO Joint Robotic System. \u003cem\u003eJournal of Orthopaedic Case Reports\u003c/em\u003e, \u003cem\u003e15\u003c/em\u003e(8), 1\u0026ndash;5. https://doi.org/10.13107/jocr.2025.v15.i08.5862\u003c/li\u003e\n\u003cli\u003eRivi\u0026egrave;re, C., Harman, C., Boughton, O., \u0026amp; Cobb, J. (2020). The Kinematic Alignment Technique for Total Knee Arthroplasty. \u003cem\u003ePersonalized Hip and Knee Joint Replacement\u003c/em\u003e, 175\u0026ndash;195. https://doi.org/10.1007/978-3-030-24243-5_16\u003c/li\u003e\n\u003cli\u003eten Noever de Brauw, G. V., Aalders, M. B., Kerkhoffs, G. M. M. J., Zuiderbaan, H. A., Keijser, L. C. M., \u0026amp; Benner, J. L. (2024). The mind matters: Psychological factors influence subjective outcomes following unicompartmental knee arthroplasty\u0026mdash;A prospective study. \u003cem\u003eKnee Surgery, Sports Traumatology, Arthroscopy\u003c/em\u003e, \u003cem\u003e33\u003c/em\u003e(1), 239\u0026ndash;251. https://doi.org/10.1002/ksa.12275\u003c/li\u003e\n\u003cli\u003eSpringborg, A. H., Jensen, C. B., Gromov, K., Troelsen, A., Kehlet, H., \u0026amp; Foss, N. B. (2024). Acute postoperative pain and catastrophizing in unicompartmental knee arthroplasty: a prospective, observational, single-center, cohort study. \u003cem\u003eRegional Anesthesia \u0026amp;amp; Pain Medicine\u003c/em\u003e. https://doi.org/10.1136/rapm-2024-105503\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Unicompartmental knee arthroplasty (UKA), Patellofemoral Joint Disease, Lower Limb Alignment, Implant Positioning, Clinical Outcomes","lastPublishedDoi":"10.21203/rs.3.rs-8496530/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8496530/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eUnicompartmental knee arthroplasty (UKA) has become an effective treatment for medial compartment osteoarthritis of the knee. However, its use in patients who also have patellofemoral joint osteoarthritis (PFOA) before surgery remains controversial. Restoring postoperative lower limb alignment and achieving accurate implant positioning are also important factors for the success of UKA, but there is still a lack of studies that combine both patient-related factors and surgical technique-related factors in the Chinese population.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eThis study retrospectively analyzed 69 Chinese patients (79 knees) with medial compartment osteoarthritis who underwent Oxford UKA between May 2017 and December 2020. The severity and location of PFOA were assessed by MRI. Postoperative coronal alignment was categorized by the femorotibial angle (FTA) into neutral, mild varus, moderate varus, and extreme/out-of-range groups. Implant positioning was classified as ideal or non-ideal according to established radiographic target ranges for aLDFA, aMPTA, PTS, and component alignment angles. Functional outcomes were evaluated using VAS, KSS, WOMAC, and Kujala score.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOxford UKA markedly improved patient function, and at an average follow-up of 66.5\u0026thinsp;\u0026plusmn;\u0026thinsp;9.6 months, no cases of prosthesis loosening or revision were observed. Postoperative functional scores did not differ by PFOA severity or lesion location. Regarding lower-limb alignment, neutral and mild varus (\u0026lt;\u0026thinsp;6\u0026deg;) knees had higher KSS-function than moderate varus and extreme/out-of-range knees and lower WOMAC scores. KSS-knee were higher in neutral and mild varus than in the extreme group. Implant positioning (ideal vs non-ideal) was not associated with postoperative scores.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eMid-term follow-up showed that Oxford UKA achieved satisfactory clinical outcomes. The severity and location of PFOA before surgery did not significantly affect postoperative knee function. Maintaining postoperative alignment within the target range (neutral to slight varus; within 6\u0026deg; of varus) may be associated with better functional recovery.\u003c/p\u003e","manuscriptTitle":"Mid-Term Clinical Outcomes of Mobile-Bearing UKA: A Retrospective Study on the Influence of Patellofemoral Joint Disease, Lower Limb Alignment, and Implant Positioning","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-16 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