Mid-term outcomes of ultra-congruent total knee arthroplasty: a comparison with the posterior-stabilized implants

Mid-term outcomes of ultra-congruent total knee arthroplasty: a comparison with the posterior-stabilized implants | 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 outcomes of ultra-congruent total knee arthroplasty: a comparison with the posterior-stabilized implants Zied Masmoudi, Sami Bahroun, Mohamed Taghouti, Maher Ben Thayer, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8682901/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract Background: Total knee arthroplasty (TKA) is an effective treatment for knee osteoarthritis, yet one in five patients remain dissatisfied after surgery. Implant design is thought to be a contributing factor to this dissatisfaction. Posterior-stabilized (PS) TKA rely on a cam-post mechanism for stability, but this design has been associated with specific complications. Ultra-congruent (UC) TKA rely on highly-conforming polyethylene instead. The aim of this study was to describe and compare the mid-term functional, clinical and radiological outcomes of the UC and PS TKA, in order to determine whether UC implants can be recommended as a safe alternative to the well-established PS implants. Methods : This retrospective study included 70 primary TKAs (36 UC, 34 PS) performed at the Adults B department, of the Mohamed Kassab Institute of orthopedics, between 2013 and 2020, with a minimum follow-up of 3 years (mean 4.7 years). Pre- and postoperative assessment included functional, clinical and radiological outcomes of the Knee Society Score (KSS). Operative time and hospital stay were noted, as well as complications and overall satisfaction. Results : Preoperative demographic, functional, clinical and radiographic parameters were comparable between groups. Operative time was shorter with UC (116.4 vs 122.9 minutes; p=0.03). Postoperatively, both designs showed significant improvements in pain, range of motion, limb alignment, KSS knee and function scores (all p<0.001). Functional outcomes were similar for UC and PS, except for better stair-climbing in Charnley A patients with UC (p=0.037). Pain, range of motion and KSS scores did not differ significantly. PS knees showed better anteroposterior stability (p=0.045). There was a trend to fewer radiolucent lines with UC (p=0.08). Overall satisfaction was high and comparable. Conclusion : At mid-term follow-up, UC TKA provided functional, clinical and radiological outcomes equivalent to PS TKA, with less bone resection, shorter operative time, better stair climbing in Charnley A patients and a tendency toward fewer tibial radiolucent lines, at the cost of a small increase in anteroposterior laxity that remained within acceptable limits. UC inserts can be recommended as a safe and effective alternative to PS designs. Osteoarthritis Knee Arthroplasty Replacement Knee Ultra-congruent Posterior-stabilized Patient satisfaction Treatment outcome Background Knee osteoarthritis is a prevalent degenerative joint disease characterized by progressive articular cartilage loss, leading to chronic pain, functional impairment, and a significant decline in quality of life. It affects approximately 10% of men and 13% of women aged 60 years and older [ 1 ], with recent epidemiological trends showing an alarming increase in prevalence among younger populations, driven by rising rates of obesity and sports-related injuries [ 2 ]. While conservative management is the standard for early-stage disease, Total Knee Arthroplasty (TKA) is the gold-standard treatment for end-stage knee osteoarthritis, offering reliable pain relief and functional restoration. However, up to 20% of patients remain dissatisfied with the outcomes of TKA [ 3 ]. This dissatisfaction has driven continuous innovation in surgical techniques and prosthetic design. Traditionally, Posterior-Stabilized (PS) implants have served as the primary solution for cases where the posterior cruciate ligament is sacrificed or incompetent. It relies on a cam-post mechanism to allow femoral rollback and provide anteroposterior stability. However, this design is associated with specific limitations, including increased polyethylene wear at the post, the risk of "patellar clunk", and higher bone resection at the intercondylar notch [ 4 ]. Ultra-Congruent (UC) implants were developed as an alternative to PS designs. It features a highly conforming, "deep-dish" polyethylene, that provides anteroposterior stability by increasing articular surface conformity and contact area, eliminating the need for cam–post mechanism. To the best of our knowledge, only a limited number of studies on this design are available. Our aim was to describe and compare the mid-term functional, clinical and radiological outcomes of UC versus PS TKA, in order to determine whether UC implants can be recommended as a safe alternative to the well-established PS design. Methods Study design This was a retrospective comparative study, of two cohorts of advanced knee osteoarthritis, treated at the Adults B department of the Mohamed Kassab Institute of orthopedics, over a period of eight years, from 2013 to 2020. And who had TKA using either a Sigma posterior-stabilized mobile-bearing implant (DePuy Synthes, Warsaw, IN, USA), or a T.KAPS ultra-congruent mobile-bearing insert (X.NOV Medical Technology, Héricourt, France). Eligibility criteria Were included patients who underwent primary total knee arthroplasty, for degenerative knee osteoarthritis, who had complete preoperative and postoperative clinical and radiological evaluations, and a minimum follow-up of three years. Tumor-related reconstructive procedures and revision total knee arthroplasties were not considered for inclusion. Patients lost to follow-up, and cases involving implant designs other than T.KAPS ultra-congruent or Sigma posterior-stabilized were excluded from the study. Patient parameters We retrospectively reviewed patients medical records to extract demographic data (age, sex, BMI and comorbidities). Pre- and postoperative functional parameters included walking distance, stair climbing ability, and walking aids use. Clinical parameters included pain intensity, range of motion (ROM), flexion contracture, extension lag, anteroposterior and mediolateral stability. Radiological evaluation included assessment of radiolucent lines on standard knee radiographs following the zonal classification described by the Knee Society [ 5 ], and the measurement of the Hip-Knee-Ankle (HKA) angle on a full-length lower limb radiograph. Surgery All procedures were performed by three high-volume orthopedic surgeons at a single center under similar conditions using a similar surgical technique. All patients underwent surgery under spinal anesthesia, without the use of a tourniquet, through a standard medial parapatellar approach. No patellar resurfacing was performed, and fixation of implants was cemented in all cases. Operative time and hospital stay were documented. Outcomes measure From the available pre- and postoperative data, the Knee Society Score (KSS) was calculated and used as the primary outcome [ 6 ]. This score assesses clinical, functional, and radiological outcomes after TKA and includes a Knee Score and a Function Score. As the Functional outcomes may be influenced by factors beyond the operated knee, they were analyzed according to Charnley classification (category A: unilateral involvement; category B: bilateral involvement and category C: multiple arthritis or medical infirmity) [ 7 ]. Patient satisfaction, a key indicator of TKA success, was evaluated using a four-point Likert scale (very satisfied, satisfied, improved, or dissatisfied). Ethical considerations This retrospective study was reviewed and approved by the ethics committee of the Mohamed Kassab Institute of Orthopedics (approval reference: IMKO-CE-2023-131). The requirement for written informed consent was waived because only de-identified data routinely collected in clinical practice were analyzed. All methods were performed in accordance with the principles of the Declaration of Helsinki. Statistical analysis Data were analyzed using SPSS software version 26.0 (SPSS, Inc., Chicago, IL, USA). Qualitative variables were expressed as absolute and relative frequencies. Quantitative variables were summarized using means, medians, and standard deviations, with outliers identified to evaluate distribution normality. Pearson’s Chi-square test was employed to compare percentages across categories, with Fisher’s exact two-tailed test applied in instances of small cell frequencies. Mean comparisons between independent groups were conducted using the independent samples Student’s t-test, while the paired samples t-test was utilized for measurements taken on the same subjects. For all statistical procedures, the significance threshold was predefined at p < 0.05. Results Patient cohorts Upon exclusion of non-exploitable records and cases failing to meet the inclusion criteria, a total of 70 total knee arthroplasties (TKA) were retained for analysis. The mean follow-up duration was 4.7 years, ranging from three to seven years. The study population was stratified into two distinct cohorts: the ultra-congruent (UC) group (n=36) and the posterior-stabilized (PS) group (n=34). Demographic data Demographic data is shown in Table 1. There was no significant difference in age (66.8 vs. 66.4 years, p=0.767), sex (92% vs. 85% females, p=0.402), BMI (34.9 vs. 34.7, p=0.917) or comorbidities (61% vs. 71%, p=0.404). The left knee was affected in 56% for both groups. Forty two percent of patients from the UC group and 35% of the PS cases had unilateral involvement (Charnley A category) while the remaining had bilateral involvement (Charnley B category) with no significant difference between the groups (p=0.584). Table 1: Comparison of demographic data between the two groups Ultra-congruent (n=36) Posterior-stabilized (n=34) P-value Age (years ± SD) 66.8 ± 4.9 66.4 ± 7.5 0.767 BMI (Kg/m² ± SD) 34.9 ± 6.1 34.7 ± 4.8 0.917 Gender, n(%) Female 33 (92%) 29(85%) 0.402 Male 3(8%) 5(15%) Comorbidities, n(%) No 14(39%) 10(29%) 0.404 Yes 22(61%) 24(71%) Affected side, n(%) Left 20(56%) 19(56%) 0.978 Right 16(44%) 15(44%) Charnley category, n(%) A 15(42%) 12(35%) 0.584 B 21(58%) 22(65%) Abbreviations: BMI=Body Mass Index, SD=Standard Deviation Preoperative data Preoperative functional data (walking distance score, stair climbing score, walking aids use and KSS function score) showed no difference between the groups, across both Charnley A and Charnley B categories (Table 2) Table 2: Comparison of preoperative functional data between the two groups Charnley A category Ultra-congruent (n=15) Posterior-stabilized (n=12) P-value Walking distance score (/50 points ± SD) 17.3 ± 5.9 16.7 ± 7.8 0.803 Stair climbing score (/50 points ± SD) 20 ± 9.3 13.8 ± 11.9 0.137 Walking aids use, n(%) 6(40%) 6(50%) 0.897 KSS function score (/100 points ± SD) 35.3 ± 15.8 27.5 ± 20.2 0.267 Charnley B category Ultra-congruent (n=21) Posterior-stabilized (n=22) P-value Walking distance score (/50 points ± SD) 14.8 ± 7.5 15 ± 5.1 0.903 Stair climbing score (/50 points ± SD) 15 ± 12.5 21.1 ± 11.9 0.108 Walking aids use, n(%) 10(47%) 8(36%) 0.661 KSS function score (/100 points ± SD) 27.4 ± 19.6 34.1 ± 17.2 0.239 Abbreviations: SD=Standard Deviation, KSS=Knee Society Score Average pain intensity score according to Knee Society scoring system was 14.7 ± 7 for UC group and 12.6 ± 7.2 for the PS group, p=0.603. ROM was similar for the two cohort (101.4° vs. 99.6°, p=0.603), as well as the HKA angle (165.5° vs. 167.2°, p=0.203). KSS knee score was 37.6/100 for UC group and 33.9/100 for PS group (p=0.175). Overall, there were no statistically significant differences between the two cohorts across all measured preoperative parameters, ensuring the comparability of the two groups (Table 3). Table 3: comparison of preoperative clinical and radiological data between the two groups Ultra-congruent (n=36) Posterior-stabilized (n=34) P-value Pain intensity score (/50points ± SD) 14.7 ± 7 12.9 ± 7.2 0.296 ROM (degrees ± SD) 101.4° ± 15° 99.6° ± 14.2° 0.603 Flexion contracture, n(%) 0° 13(36%) 7(21%) 0.241 ≥5° 23(64%) 27(79%) Anteroposterior stability, n(%) 5-9mm 3(8%) 3(9%) 0.942 <5mm 33(92%) 31(91%) Mediolateral stability, n(%) 5-9° 5(14%) 5(15%) 0.922 <5° 31(86%) 29(85%) HKA angle (degrees ± SD) 165.5° ± 5.2° 167.2° ± 5.5° 0.203 KSS knee score (/100points ± SD) 37.6 ± 10.8 33.9 ± 11.8 0.175 Abbreviations: ROM = Range of Motion, HKA = Hip-Knee-Ankle, KSS= Knee Society Score, SD=Standard Deviation Operative data Mean operative time was significantly shorter for the UC group at 116.4 ± 10.7 min compared to 122.9 ± 14 min for the PS group, p = 0.03. Blood transfusion was required in two UC cases (6%) and in none of the PS cases (p = 0.163). Mean hospital stay was comparable, averaging 2.8 ± 1.8 days in the UC group and 3.1 ± 2.1 days in the PS group (p = 0.431). Functional outcomes Postoperatively, UC and PS TKA patients showed significant improvements of walking distance, stair climbing ability, walking aids use and KSS function (all p<0.05). When comparing the two groups, there was no significant difference in functional outcomes, except for better stair climbing for UC patients in Charnley A category (p=0.037) (Table 5). KSS function scores were similar in Charnley A category (70.7 for UC vs. 64.2 for PS, p= 0.316), and in Charnley B category (57.4 for UC vs. 55 for PS, p=0.709) (Table 4). Table 4: Comparison of functional outcomes between the two groups Charnley A category Ultra-congruent (n=15) Posterior-stabilized (n=12) P-value Walking distance score (/50 points ± SD) 32.7 ± 8 33.3 ± 10.7 0.855 Stair climbing score (/50 points ± SD) 38.7 ± 7.4 31.7 ± 9.1 0.037 Walking aids use, n(%) 2(13%) 2(17%) 0.809 KSS function score (/100 points ± SD) 70.7 ± 13.7 64.2 ± 19.3 0.316 Charnley B category Ultra-congruent (n=21) Posterior-stabilized (n=22) P-value Walking distance score (/50 points ± SD) 29 ± 10.9 25.9 ± 8.5 0.298 Stair climbing score (/50 points ± SD) 30 ± 11.5 30.9 ± 10.1 0.784 Walking aids use, n(%) 7(33%) 7(32%) 0.916 KSS function score (/100 points ± SD) 57.4 ± 22.2 55 ± 19.3 0.709 Abbreviations: SD=Standard Deviation, KSS=Knee Society Score Clinical outcomes Postoperatively, pain intensity score, ROM, and KSS knee score showed significant improvements across both cohorts (all p<0.001). There was no significant difference between the UC and PS groups in pain intensity scores (43.6 ± 5.3 for UC group vs. 41.3 ± 7 for PS group, p=0.126) or average ROM (113.3° ± 9.3 for UC TKA vs. 113.7° ± 10.4 for PS TKA, p=0.884). However, we noted better anteroposterior stability for PS implants, at 90° flexion, compared with UC TKA (p=0.045). The mean postoperative KSS knee score was 89.9 ± 7.2 in the UC group compared with 86.4 ± 9.9 in the PS group, showing a non-significant trend toward better results with the UC design (p=0.09) (Table 5). Table 5: comparison of clinical outcomes between the two groups Ultra-congruent (n=36) Posterior-stabilized (n=34) P-value Pain intensity score (/50points ± SD) 43.6 ± 5.3 41.3 ± 7 0.296 ROM (degrees ± SD) 113.3° ± 9.3° 113.3° ± 10.4° 0.603 Flexion contracture, n(%) 0° 35(97%) 31(91%) 0.241 ≥5° 1(3%) 3(9%) Anteroposterior stability, n(%) 5-9mm 4(11%) 0(0%) 0.942 <5mm 32(89%) 34(100%) KSS knee score (/100points ± SD) 89.9 ± 7.2 86.4 ± 9.9 0.175 Abbreviations: ROM = Range of Motion, HKA = Hip-Knee-Ankle, KSS= Knee Society Score, SD=Standard Deviation Radiological outcomes The mean postoperative HKA angle was 177.7° ± 1.4° for UC group, and 177.2° ± 2.3° for PS group (p=0.338). Non-progressive radiolucent lines (RLLs) were most frequently identified in Tibial Zone 1 (medial plateau) on the anteroposterior radiographs. These were documented in 2 cases of the UC group and 4 cases of the PS group (Table 6). Table 6: Comparison of radiological outcomes between the two grouups Ultra-congruent (n=36) Posterior-stabilized (n=34) P-value HKA (degrees ± SD) 177.7° ± 1.4° 177.2° ± 2.3° 0.338 Tibial radiolucent lines (Anteroposterior radiograph) None 34(94%) 27(80%) 0.080 Zone 1 2(6%) 4(11%) Zone 2 0(0%) 1(3%) Zone 1 + 2 0(0%) 1(3%) Zone 1 + 2 + 3 0(0%) 1(3%) Tibial radiolucent lines (Lateral radiograph) None 36(100%) 31(91%) 0.091 Zone 1 0(0%) 1(3%) Zone 2 0(0%) 1(3%) Zone 1 + 2 + 3 0(0%) 1(3%) Abbreviations: HKA = Hip-Knee-Ankle, SD=Standard Deviation There was a non-significant trend toward a lower incidence of tibial radiolucent lines in UC TKA compared to PS TKAs, in both anteroposterior (p=0.08) and lateral radiographs (p=0.091). Progressive radiolucency that extended to all tibial zones was observed in one case, which belonged to the PS group. These findings were highly suggestive of aseptic implant loosening, and the patient subsequently underwent revision surgery. This was the only major complications recorded in our series. And the difference in complication rates did not reach statistical significance (p=0.486). Satisfaction Overall satisfaction was similar between the two groups (p=0.229), with 31% of UC and 26% of PS patients reporting very high satisfaction, and 61% of UC and 53% of PS patients describing themselves as satisfied (Table 7). Table 7: comparison of satisfaction between the two groups Ultra-congruent (n=36) Posterior-stabilized (n=34) P-value Very satisfied 11(31%) 9(26%) 0.229 Satisfied 22(61%) 18(53%) Improved 2(6%) 7(21%) Dissatisfied 1(3%) 0(0%) Discussion Several findings emerged from the analysis of our data. First, both UC and PS TKAs provided significant improvement in pain relief, ROM and limb alignment. Our data further demonstrated that UC TKA provides functional, clinical and radiological outcomes equivalent to PS TKA, with less bone resection, shorter operative time (p=0.03), better stair climbing in Charnley A patients (p=0.037) and a non-significant trend toward fewer tibial radiolucent lines, at the cost of a decrease in anteroposterior stability, that did not adversely affect KSS scores or patient satisfaction. Pain intensity Our study found similar pain intensity scores between UC and PS TKA. Pain is the primary indicator of patient satisfaction and accounts for 50% of the KSS knee score [6]. However, its assessment remains inherently subjective and may be influenced by both physical and psychological factors. Our findings align with the meta-analysis by Raja [8], which reported similar KSS pain scores between the UC and PS groups (p=0.15). Lützner et al. [4] found no significant differences in pain outcomes at five years; however, at one and three years postoperatively, the Oxford Knee score (OKS) pain score was significantly better for UC patients. This suggests that, although pain outcomes are equivalent at mid-term follow-up, UC TKA may provide a faster recovery pattern compared with PS TKA. Range of motion In the present study, no significant difference in ROM was observed between the UC and PS TKA groups. Current literature remains divided regarding which design provides superior postoperative ROM. A 2018 meta-analysis [9] concluded that the PS group achieved significantly greater ROM than the UC group. The underlying rationale for superior flexion in PS designs is attributed to femoral rollback: the physiological posterior translation of the femorotibial contact point during flexion, which prevents posterior impingement, thereby allowing deeper flexion [10–12]. Kinematic studies have demonstrated that the cam-post mechanism in PS TKA induces significantly more posterior rollback compared to the conforming geometry of UC TKA [13–15]. Conversely, a more recent 2021 systematic review and meta-analysis [8] found no statistically significant difference in postoperative ROM between the two designs. The contradiction between studies showing significant kinematic advantages for PS TKA and those showing no difference in ROM suggests that other factors are highly influential. Soft tissue balancing, restoration of the joint line, and postoperative physiotherapy have a major impact on final ROM [4,13]. Furthermore, femoral external rotation is also crucial factor for maximum knee flexion [16]. Bae’s meta-analysis [9] showed that UC TKA had significantly more femoral external rotation compared to PS TKA. This enhanced rotational freedom may compensate for reduced rollback, explaining the equivalent ROM observed in several studies. Anteroposterior stability In the present study, PS TKA demonstrated superior clinical anteroposterior stability at 90° flexion compared to UC TKA (p=0.045). A meta-analysis by Wenzel et al. reported that PS TKAs achieve significantly better anteroposterior stability in deep flexion compared to UC designs [17]. However, the mechanism of constraint is flexion-dependent: according to Scott [18], the femoral cam in posterior-stabilized designs does not engage the polyethylene post until approximately 60° of flexion, whereas the highly conforming polyethylene insert with the anterior and posterior lips provides more consistent stability throughout the range of motion. Correspondingly, several studies have reported similar or superior anteroposterior stability for UC TKA in the 0–30° flexion range, while PS TKA tends to demonstrate greater stability beyond 60° of flexion [13,18,19]. This is particularly relevant since most daily activities depend on knee stability from extension to mid-flexion rather than at 90° of flexion [15,20]. Stair climbing In our study, Charnley A patients with UC TKA had significantly better stair climbing scores, compared to patients with PS TKA (p = 0.037). Few studies detail the stair climbing subscore in their results. However, there is some evidence in literature to better outcomes for UC in activities with high patellofemoral load: Lützner’s RCT [4] reported significantly better OKS functional scores for UC implants at one and three years postoperatively. Specifically, UC designs outperformed PS designs in tasks with high patellofemoral load, such as rising from a chair (p=0.025) and kneeling (p=0.052) [4]. These findings contrast with those of Sur et al. [21], who found no statistically significant differences between the two groups in KSS stair climbing scores at 5 years follow-up (p = 0.328). Knee Society Score In the present study, KSS functional scores were comparable between UC and PS TKA groups for both Charnley Category A (p = 0.316) and Category B patients (p = 0.709). These findings align with several meta-analyses [8,17] and randomized controlled trials [14,15,18,22–25] that reported no mid-to-long-term functional differences between the designs. However, some literature suggests transient functional advantages for the UC design. Carlson et al. [26] observed significantly higher KSS functional scores for UC implants at 6 months (p = 0.04), 1 year (p = 0.03), and 2 years (p = 0.04) postoperatively. Notably, these differences equilibrated by the 5-year follow-up. In our cohort, there was a trend toward better KSS Knee score with UC TKA, compared to PS TKA, although this did not reach statistical significance (p=0.09). The predominant finding across multiple high-level studies is that the intrinsic kinematic differences between UC and PS implants do not translate into statistically significant differences in the overall KSS knee score: Wenzel‘s 2023 systematic review and meta-analysis [17] showed that despite better anteroposterior stability and more femoral rollback of PS implants, there was no statistically significant difference in the KSS knee score between the UC and PS TKAs. Radiological outcomes, complications and revision rates Our findings showed a trend toward fewer radiolucent lines in the UC group compared to the PS group. A Meta-analysis by Tsai et al. [28] also reported fewer radiolucent lines in UC TKA compared to PS TKA. However, the difference did not reach statistical significance. In theory, eliminating the PS tibial post removes a point of stress that could potentially generate polyethylene debris and micro-motion at the tibial component [28]. Moreover, the lower incidence of radiolucent lines in our UC group may be attributable to the bone-preserving nature of the design. By eliminating the femoral box cut, UC implants preserve intercondylar bone stock, maintaining cortical support and reducing stress at the bone-implant interface [29]. This bone-preserving approach also influences operative time, Lützner et al. [4] cited the intercondylar box preparation as a factor for the 10-minute increase in operative time for PS TKAs (p < 0.001). Our study showed similar results, with UC surgeries lasting 6.5 minutes shorter on average than PS procedures (p=0.03). Beyond surgical time, the additional bone resection required for PS designs may impact blood loss. In an RCT of 111 patients, Scott et al. [48] observed a steeper postoperative hemoglobin decline in the PS group compared to UC group. While the overall decline was not statistically significant, the study did identify a significantly higher transfusion rate among male patients within the PS cohort ( p = 0.039).. Furthermore, avoiding intercondylar bone resection offers a long-term advantage for younger patients, who may require revision surgery. Indeed, preserving bone stock often negates the need for complex augments and extensive bone grafts during revision surgery [30]. It also minimizes the risk of periprosthetic fractures during component removal and facilitates a more accurate restoration of the joint line in the revision setting [4]. Moreover, there is some evidence to lower revision rates with UC TKA: in his study of 67,523 primary TKA using the same Genesis II knee system with different inserts, Dalton [31] reported an 8.3% revision rate at 18 years for UC implants, compared with 8.9% for PS implants (8.9%), the difference was statistically significant (HR 1.19, 95% CI 1.08-1.31, p < 0.001). Satisfaction Overall, 31% of UC and 26% of PS patients reported very high satisfaction, and 61% of UC and 53% of PS patients described themselves as satisfied. There was no significant difference between the two groups (p=0.229). Our findings are similar to Machihindra’s [32] results. Kim et al. [15] compared UC and PS TKA within the same patients and found no difference in satisfaction, joint perception or side preference between the two knees. Study strengths To our knowledge, this study represents the first comparative analysis of ultra-congruent total knee arthroplasty in the MENA region. It provides valuable mid-term data from a region that is underrepresented in the arthroplasty literature. The consistency of our findings with international data strengthens the confidence in UC inserts as an alternative to PS inserts. Methodological bias was strictly controlled through independent assessment, as all clinical and radiographic data were collected by a single observer not involved in the surgical procedures. Furthermore, the restriction of this study to a single institution with a standardized surgical protocol and uniform operative conditions minimized technical confounding variables between the two statistically comparable groups. Study limitations This study has several limitations. First, the retrospective design inherently limits control over data collection and introduces potential selection bias, as the surgical rationale for choosing a UC versus a PS implant was not documented. Second, our sample size of 70 patients is relatively small, while it provided sufficient power to detect significant differences in surgical efficiency and reported outcomes, it remains underpowered to evaluate rare complications or long-term revision rates. Larger randomized controlled trials with longer follow-up are needed to confirm the long-term equivalence of UC TKA to PS TKA in terms of patient-reported outcomes, and to determine whether the radiographic advantages suggested in our series translates into better survivorship. Conclusion Despite the differences in kinematics, UC TKA provided equivalent mid-term outcomes to PS TKA, with less bone resection, less operative time and better stair climbing, at the cost of a minor increase in anteroposterior laxity that remained within acceptable limits. And thus, we can safely recommend UC inserts as an alternative to PS designs, especially in young patient, where bone stock preservation is a priority. Abbreviations TKA Total Knee Arthroplasty PS Posterior-Stabilized UC Ultra-congruent BMI Body-Mass-Index ROM Range Of Motion HKA Hip-Knee-Ankle KSS Knee Society Score RLL RadioLucent Lines OKS Oxford Knee Score Declarations Data availability The datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request. Acknowledgements None. Funding No funding was received for this study. Author information Authors and Affiliations 1 Mohamed Kassab Institute of Orthopedics, Manouba, Tunisia Zied Masmoudi ; Sami Bahroun ; Mohamed Taghouti ; Maher Ben Thayer ; Mohamed Samir Daghfous ²Tunis El Manar University, Tunisia Zied Masmoudi ; Sami Bahroun ; Mohamed Taghouti ; Maher Ben Thayer; Sofiane Masmoudi; Mohamed Samir Daghfous Contributions Z.M. and S.B. contributed to the study conception and design. M.T. and M.B.T. collected and analyzed the data. S.M performed the statistical analysis and interpreted the results. M.S.D. supervised the project and provided critical revisions. Z.M. and S.B. wrote the main manuscript text. All authors reviewed and approved the final manuscript. Corresponding author Correspondence to Zied Masmoudi. Ethics declarations Ethics approval and consent to participate This retrospective study was reviewed and approved by the ethics committee of the Mohamed Kassab Institute of Orthopedics (approval reference: IMKO-CE-2023-131). The requirement for written informed consent was waived because only de-identified data routinely collected in clinical practice were analyzed. All methods were performed in accordance with the principles of the Declaration of Helsinki. Consent for publication Not applicable. Competing interests The authors declare no competing interests. References Heidari B. Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I. Casp J Intern Med. 2011;2(2):205–12. Li E, Tan J, Xu K, Pan Y, Xu P. Global burden and socioeconomic impact of knee osteoarthritis: a comprehensive analysis. Front Med. 2024 May 16;11:1323091. DeFrance MJ, Scuderi GR. Are 20% of Patients Actually Dissatisfied Following Total Knee Arthroplasty? A Systematic Review of the Literature. J Arthroplasty. 2023 Mar;38(3):594–9. Lützner J, Beyer F, Lützner C, Riedel R, Tille E. Ultracongruent insert design is a safe alternative to posterior cruciate-substituting total knee arthroplasty: 5-year results of a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2022 Sept;30(9):3000–6. Ewald FC. The Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System: Clin Orthop. 1989 Nov;248:9-12. Insall JN, Dorr LD, Scott RD, Norman W. Rationale, of The Knee Society Clinical Rating System: Clin Orthop. 1989 Nov;248:13-14. Charnley J. The long-term results of low-friction arthroplasty of the hip performed as a primary intervention. J Bone Joint Surg Br. 1972 Feb;54-B(1):61–76. S.Raja B, Gowda AKS, Ansari S, Choudhury AK, Kalia RB. Comparison of Functional Outcomes, Femoral Rollback and Sagittal Stability of Anterior-Stabilized Versus Posterior-Stabilized Total Knee Arthroplasty: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Indian J Orthop. 2021 Aug 23;55(5):1076–86. Bae JH, Yoon JR, Sung JH, Shin YS. Posterior-stabilized inserts are preferable to cruciate-substituting ultracongruent inserts due to more favourable kinematics and stability. Knee Surg Sports Traumatol Arthrosc. 2018 Nov;26(11):3300–10. Ewald FC, Jacobs MA, Miegel RE, Walker PS, Poss R, Sledge CB. Kinematic total knee replacement. J Bone Joint Surg Am. 1984 Sept;66(7):1032–40. Andriacchi TP, Galante JO. Retention of the posterior cruciate in total knee arthroplasty. J Arthroplasty. 1988;3 Suppl:S13-19. Freeman M a. R, Pinskerova V. The movement of the normal tibio-femoral joint. J Biomech. 2005 Feb;38(2):197–208. Fritzsche H, Beyer F, Postler A, Lützner J. Different intraoperative kinematics, stability, and range of motion between cruciate-substituting ultracongruent and posterior-stabilized total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2018 May 1;26(5):1465–70. Lützner J, Beyer F, Dexel J, Fritzsche H, Lützner C, Kirschner S. No difference in range of motion between ultracongruent and posterior stabilized design in total knee arthroplasty: a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc. 2017 Nov;25(11):3515–21. Kim YB, Choi HS, Kang EM, Park S, Seo GW, Chun DI, et al. Trends of Total Knee Arthroplasty According to Age Structural Changes in Korea from 2011 to 2018. Int J Environ Res Public Health. 2021 Dec 20;18(24):13397. Dennis DA, Komistek RD, Mahfouz MR, Walker SA, Tucker A. A multicenter analysis of axial femorotibial rotation after total knee arthroplasty. Clin Orthop. 2004 Nov 1;(428):180–9. Wenzel AN, Hasan SA, Chaudhry YP, Mekkawy KL, Oni JK, Khanuja HS. Ultracongruent Designs Compared to Posterior-Stabilized and Cruciate-Retaining Tibial Inserts – What Does the Evidence Tell Us? A Systematic Review and Meta-Analysis. J Arthroplasty. 2023 Dec 1;38(12):2739-2749.e7. Scott DF. Prospective Randomized Comparison of Posterior-Stabilized Versus Condylar-Stabilized Total Knee Arthroplasty: Final Report of a Five-Year Study. J Arthroplasty. 2018 May;33(5):1384–8. Roberti di Sarsina T, Alesi D, Di Paolo S, Zinno R, Pizza N, Marcheggiani Muccioli GM, et al. In vivo kinematic comparison between an ultra-congruent and a posterior-stabilized total knee arthroplasty design by RSA. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2022 Aug;30(8):2753–8. Davies AP. Rating systems for total knee replacement. The Knee. 2002 Dec;9(4):261–6. Sur YJ, Koh IJ, Park SW, Kim HJ, In Y. Condylar-Stabilizing Tibial Inserts Do Not Restore Anteroposterior Stability After Total Knee Arthroplasty. J Arthroplasty. 2015 Apr 1;30(4):587–91. Kim TW, Lee SM, Seong SC, Lee S, Jang J, Lee MC. Different intraoperative kinematics with comparable clinical outcomes of ultracongruent and posterior stabilized mobile-bearing total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2016 Sept;24(9):3036–43. Akti S, Karakus D, Sezgin EA, Cankaya D. No differences in clinical outcomes or isokinetic performance between cruciate-substituting ultra-congruent and posterior stabilized total knee arthroplasties: a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc. 2021;29(10):1795. Jang SW, Kim MS, Koh IJ, Sohn S, Kim C, In Y. Comparison of Anterior-Stabilized and Posterior-Stabilized Total Knee Arthroplasty in the Same Patients: A Prospective Randomized Study. J Arthroplasty. 2019 Aug;34(8):1682–9. Laskin RS, Maruyama Y, Villaneuva M, Bourne R. Deep-dish congruent tibial component use in total knee arthroplasty: a randomized prospective study. Clin Orthop. 2000 Nov;(380):36–44. Carlson BJ, Jones BK, Scott DF. A prospective comparison of total knee arthroplasty using ultra-congruent, condylar-stabilizing, and posterior-stabilized devices implanted with kinematic alignment: better 2-year outcomes with ultra-congruent. Knee Surg Sports Traumatol Arthrosc. 2023;31(3):1026–33. Rosa AD. Comparison of ultra-congruent anterior-stabilized vs. a posterior cruciate substituting total knee arthroplasty for osteoarthritis with severe varus knee deformity: comparable 2 year outcomes with two design. Eur Rev Med Pharmacol Sci. 2023 Sep;27(17):7968-76. Tsai YL, Tsai SHL, Lin CH, Lin CR, Hu CC. The Effect of Congruent Tibial Inserts in Total Knee Arthroplasty: A Network Meta-Analysis of Randomized Controlled Trials. Life. 2023 Sept;13(9):1942. Rajguhan TV, Vanchi PK, Prashanth KRT, Veeraraghavan RR, Murugesan MK. Inserting the best knee: A short-term analysis of posterior stabilized versus cruciate substituting ultracongruent tibial inserts for total knee replacement. J Musculoskelet Surg Res. 2023 July 31;7(3):180–5. Kurtz WB, Slamin JE, Doody SW. Bone Preservation in a Novel Patient Specific Total Knee Replacement. Reconstr Rev. 2016 Apr 26;6(1):133–133. Dalton P, Holder C, Rainbird S, Lewis PL. Survivorship Comparisons of Ultracongruent, Cruciate-Retaining and Posterior-Stabilized Tibial Inserts Using a Single Knee System Design: Results From the Australian Orthopedic Association National Joint Replacement Registry. J Arthroplasty. 2022 Mar;37(3):468–75. Machhindra MV, Kang JY, Kang YG, Chowdhry M, Kim TK. Functional Outcomes of a New Mobile-Bearing Ultra-Congruent TKA System: Comparison With the Posterior Stabilized System. J Arthroplasty. 2015 Dec;30(12):2137–42. Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8682901","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":616528380,"identity":"5cb8ccf6-b66c-484b-ba55-3949356f648e","order_by":0,"name":"Zied Masmoudi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA60lEQVRIiWNgGAWjYBACewQzsYGBoQJIMzM34NViiJAGaTkD0sKIX4vBATgzgYGBsQ3EIKTl9gHWDT/+bJMzOJ7cwPhzXm00fztQy4+Kbbi1nEtgu9nbdtvY4MzDBgbJbcdzZxxmbGDsOXMbt5YzDGw3eBtuJ264AfSL4bZjuQ1ALcyMbfi13PzzB6olcc6x3PnEaLnNwwbVcrChJncDIS2GPUBZWaBfJIF+Odhw7EDuRqCWg/j8Ys/DfOzmmz+35fiOpz98+KOmLnfe+cMHH/yowK0FJRYOMDAchjGIB3WkKB4Fo2AUjIIRAgBb52YIhETDvAAAAABJRU5ErkJggg==","orcid":"","institution":"Mohamed Kassab Institute of Orthopedics","correspondingAuthor":true,"prefix":"","firstName":"Zied","middleName":"","lastName":"Masmoudi","suffix":""},{"id":616528381,"identity":"4b9f4895-9ca3-4a52-a519-f6404b975546","order_by":1,"name":"Sami Bahroun","email":"","orcid":"","institution":"Mohamed Kassab Institute of Orthopedics","correspondingAuthor":false,"prefix":"","firstName":"Sami","middleName":"","lastName":"Bahroun","suffix":""},{"id":616528382,"identity":"923127f1-3e11-491c-a10a-1e0df7b91b84","order_by":2,"name":"Mohamed Taghouti","email":"","orcid":"","institution":"Mohamed Kassab Institute of Orthopedics","correspondingAuthor":false,"prefix":"","firstName":"Mohamed","middleName":"","lastName":"Taghouti","suffix":""},{"id":616528383,"identity":"5638dd57-dc87-4fed-892a-6b352845c8d3","order_by":3,"name":"Maher Ben Thayer","email":"","orcid":"","institution":"Mohamed Kassab Institute of Orthopedics","correspondingAuthor":false,"prefix":"","firstName":"Maher","middleName":"Ben","lastName":"Thayer","suffix":""},{"id":616528384,"identity":"f7c741ab-cb6c-46e4-9deb-50198d705029","order_by":4,"name":"Sofiane Masmoudi","email":"","orcid":"","institution":"Tunis El Manar University","correspondingAuthor":false,"prefix":"","firstName":"Sofiane","middleName":"","lastName":"Masmoudi","suffix":""},{"id":616528386,"identity":"0839ae2e-3efe-4205-805d-c0e873ae5012","order_by":5,"name":"Mohamed Samir Daghfous","email":"","orcid":"","institution":"Mohamed Kassab Institute of Orthopedics","correspondingAuthor":false,"prefix":"","firstName":"Mohamed","middleName":"Samir","lastName":"Daghfous","suffix":""}],"badges":[],"createdAt":"2026-01-24 00:08:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8682901/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8682901/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107479254,"identity":"7588fcb4-f4a6-4436-97c7-1fcf98834567","added_by":"auto","created_at":"2026-04-22 01:21:15","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1214726,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8682901/v1/b57a7e94-5bd4-4d8f-964a-ad119f9b93f4.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Mid-term outcomes of ultra-congruent total knee arthroplasty: a comparison with the posterior-stabilized implants","fulltext":[{"header":"Background","content":"\u003cp\u003eKnee osteoarthritis is a prevalent degenerative joint disease characterized by progressive articular cartilage loss, leading to chronic pain, functional impairment, and a significant decline in quality of life. It affects approximately 10% of men and 13% of women aged 60 years and older [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e], with recent epidemiological trends showing an alarming increase in prevalence among younger populations, driven by rising rates of obesity and sports-related injuries [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhile conservative management is the standard for early-stage disease, Total Knee Arthroplasty (TKA) is the gold-standard treatment for end-stage knee osteoarthritis, offering reliable pain relief and functional restoration.\u003c/p\u003e \u003cp\u003eHowever, up to 20% of patients remain dissatisfied with the outcomes of TKA [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. This dissatisfaction has driven continuous innovation in surgical techniques and prosthetic design.\u003c/p\u003e \u003cp\u003eTraditionally, Posterior-Stabilized (PS) implants have served as the primary solution for cases where the posterior cruciate ligament is sacrificed or incompetent. It relies on a cam-post mechanism to allow femoral rollback and provide anteroposterior stability. However, this design is associated with specific limitations, including increased polyethylene wear at the post, the risk of \"patellar clunk\", and higher bone resection at the intercondylar notch [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eUltra-Congruent (UC) implants were developed as an alternative to PS designs. It features a highly conforming, \"deep-dish\" polyethylene, that provides anteroposterior stability by increasing articular surface conformity and contact area, eliminating the need for cam\u0026ndash;post mechanism.\u003c/p\u003e \u003cp\u003eTo the best of our knowledge, only a limited number of studies on this design are available.\u003c/p\u003e \u003cp\u003eOur aim was to describe and compare the mid-term functional, clinical and radiological outcomes of UC versus PS TKA, in order to determine whether UC implants can be recommended as a safe alternative to the well-established PS design.\u003c/p\u003e"},{"header":"Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design\u003c/h2\u003e \u003cp\u003eThis was a retrospective comparative study, of two cohorts of advanced knee osteoarthritis, treated at the Adults B department of the Mohamed Kassab Institute of orthopedics, over a period of eight years, from 2013 to 2020. And who had TKA using either a Sigma posterior-stabilized mobile-bearing implant (DePuy Synthes, Warsaw, IN, USA), or a T.KAPS ultra-congruent mobile-bearing insert (X.NOV Medical Technology, H\u0026eacute;ricourt, France).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eEligibility criteria\u003c/h3\u003e\n\u003cp\u003eWere included patients who underwent primary total knee arthroplasty, for degenerative knee osteoarthritis, who had complete preoperative and postoperative clinical and radiological evaluations, and a minimum follow-up of three years. Tumor-related reconstructive procedures and revision total knee arthroplasties were not considered for inclusion. Patients lost to follow-up, and cases involving implant designs other than T.KAPS ultra-congruent or Sigma posterior-stabilized were excluded from the study.\u003c/p\u003e\n\u003ch3\u003ePatient parameters\u003c/h3\u003e\n\u003cp\u003eWe retrospectively reviewed patients medical records to extract demographic data (age, sex, BMI and comorbidities). Pre- and postoperative functional parameters included walking distance, stair climbing ability, and walking aids use. Clinical parameters included pain intensity, range of motion (ROM), flexion contracture, extension lag, anteroposterior and mediolateral stability. Radiological evaluation included assessment of radiolucent lines on standard knee radiographs following the zonal classification described by the Knee Society [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], and the measurement of the Hip-Knee-Ankle (HKA) angle on a full-length lower limb radiograph.\u003c/p\u003e\n\u003ch3\u003eSurgery\u003c/h3\u003e\n\u003cp\u003eAll procedures were performed by three high-volume orthopedic surgeons at a single center under similar conditions using a similar surgical technique. All patients underwent surgery under spinal anesthesia, without the use of a tourniquet, through a standard medial parapatellar approach. No patellar resurfacing was performed, and fixation of implants was cemented in all cases. Operative time and hospital stay were documented.\u003c/p\u003e\n\u003ch3\u003eOutcomes measure\u003c/h3\u003e\n\u003cp\u003eFrom the available pre- and postoperative data, the Knee Society Score (KSS) was calculated and used as the primary outcome [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. This score assesses clinical, functional, and radiological outcomes after TKA and includes a Knee Score and a Function Score.\u003c/p\u003e \u003cp\u003eAs the Functional outcomes may be influenced by factors beyond the operated knee, they were analyzed according to Charnley classification (category A: unilateral involvement; category B: bilateral involvement and category C: multiple arthritis or medical infirmity) [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePatient satisfaction, a key indicator of TKA success, was evaluated using a four-point Likert scale (very satisfied, satisfied, improved, or dissatisfied).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eEthical considerations\u003c/h2\u003e \u003cp\u003eThis retrospective study was reviewed and approved by the ethics committee of the Mohamed Kassab Institute of Orthopedics (approval reference: IMKO-CE-2023-131).\u003c/p\u003e \u003cp\u003eThe requirement for written informed consent was waived because only de-identified data routinely collected in clinical practice were analyzed.\u003c/p\u003e \u003cp\u003eAll methods were performed in accordance with the principles of the Declaration of Helsinki.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using SPSS software version 26.0 (SPSS, Inc., Chicago, IL, USA). Qualitative variables were expressed as absolute and relative frequencies. Quantitative variables were summarized using means, medians, and standard deviations, with outliers identified to evaluate distribution normality. Pearson\u0026rsquo;s Chi-square test was employed to compare percentages across categories, with Fisher\u0026rsquo;s exact two-tailed test applied in instances of small cell frequencies. Mean comparisons between independent groups were conducted using the independent samples Student\u0026rsquo;s t-test, while the paired samples t-test was utilized for measurements taken on the same subjects. For all statistical procedures, the significance threshold was predefined at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003ePatient cohorts\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eUpon exclusion of non-exploitable records and cases failing to meet the inclusion criteria, a total of 70 total knee arthroplasties (TKA) were retained for analysis. The mean follow-up duration was 4.7 years, ranging from three to seven years.\u003c/p\u003e\n\u003cp\u003eThe study population was stratified into two distinct cohorts: the ultra-congruent (UC) group (n=36) and the posterior-stabilized (PS) group (n=34).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDemographic data\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDemographic data is shown in Table 1. There was no significant difference in age (66.8 vs. 66.4 years, p=0.767), sex (92% vs. 85% females, p=0.402), BMI (34.9 vs. 34.7, p=0.917) or comorbidities (61% vs. 71%, p=0.404). The left knee was affected in 56% for both groups. Forty two percent of patients from the UC group and 35% of the PS cases had unilateral involvement (Charnley A category) while the remaining had bilateral involvement (Charnley B category) with no significant difference between the groups (p=0.584).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1: Comparison of demographic data between the two groups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" colspan=\"2\" style=\"width: 44px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 23px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent (n=36)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 21px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=34)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 44px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (years \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e66.8 \u0026plusmn; 4.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e66.4 \u0026plusmn; 7.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.767\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 44px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eBMI (Kg/m\u0026sup2; \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e34.9 \u0026plusmn; 6.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e34.7 \u0026plusmn; 4.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.917\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 30px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eGender, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eFemale\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e33 (92%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e29(85%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.402\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eMale\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e3(8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e5(15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 30px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eComorbidities, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eNo\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e14(39%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e10(29%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.404\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eYes\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e22(61%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e24(71%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 30px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAffected side, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eLeft\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e20(56%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e19(56%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.978\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eRight\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e16(44%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e15(44%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 30px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCharnley category, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eA\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e15(42%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e12(35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.584\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 13px;\"\u003e\n \u003cp\u003eB\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 23px;\"\u003e\n \u003cp\u003e21(58%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e22(65%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAbbreviations: BMI=Body Mass Index, SD=Standard Deviation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreoperative data\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;Preoperative functional data (walking distance score, stair climbing score, walking aids use and KSS function score) showed no difference between the groups, across both Charnley A and Charnley B categories (Table 2)\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2: Comparison of preoperative functional data between the two groups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"99%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCharnley A category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=15)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=12)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking distance score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e17.3 \u0026plusmn; 5.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e16.7 \u0026plusmn; 7.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.803\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStair climbing score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e20 \u0026plusmn; 9.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e13.8 \u0026plusmn; 11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.137\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking aids use, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e6(40%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e6(50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.897\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKSS function score (/100 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e35.3 \u0026plusmn; 15.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e27.5 \u0026plusmn; 20.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.267\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCharnley B category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=21)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=22)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking distance score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e14.8 \u0026plusmn; 7.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e15 \u0026plusmn; 5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.903\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStair climbing score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e15 \u0026plusmn; 12.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e21.1 \u0026plusmn; 11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.108\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking aids use, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e10(47%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e8(36%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.661\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKSS function score (/100 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e27.4 \u0026plusmn; 19.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e34.1 \u0026plusmn; 17.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.239\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAbbreviations: SD=Standard Deviation, KSS=Knee Society Score\u003c/p\u003e\n\u003cp\u003eAverage pain intensity score according to Knee Society scoring system was 14.7 \u0026plusmn; 7 for UC group and 12.6 \u0026plusmn; 7.2 for the PS group, p=0.603. ROM was similar for the two cohort (101.4\u0026deg; vs. 99.6\u0026deg;, p=0.603), as well as the HKA angle (165.5\u0026deg; vs. 167.2\u0026deg;, p=0.203).\u003c/p\u003e\n\u003cp\u003eKSS knee score was 37.6/100 for UC group and 33.9/100 for PS group (p=0.175).\u003c/p\u003e\n\u003cp\u003eOverall, there were no statistically significant differences between the two cohorts across all measured preoperative parameters, ensuring the comparability of the two groups (Table 3).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3: comparison of preoperative clinical and radiological data between the two groups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" colspan=\"2\" style=\"width: 47px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 21px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=36)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 20px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=34)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" colspan=\"2\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePain intensity score (/50points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e14.7 \u0026plusmn; 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e12.9 \u0026plusmn; 7.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.296\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eROM (degrees \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e101.4\u0026deg; \u0026plusmn; 15\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e99.6\u0026deg; \u0026plusmn; 14.2\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.603\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFlexion contracture, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e13(36%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e7(21%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.241\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u0026ge;5\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e23(64%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e27(79%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAnteroposterior stability, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e5-9mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e3(8%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e3(9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.942\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u0026lt;5mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e33(92%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e31(91%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eMediolateral stability, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e5-9\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e5(14%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e5(15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.922\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u0026lt;5\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e31(86%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e29(85%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHKA angle (degrees \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e165.5\u0026deg; \u0026plusmn; 5.2\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e167.2\u0026deg; \u0026plusmn; 5.5\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.203\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKSS knee score (/100points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e37.6 \u0026plusmn; 10.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e33.9 \u0026plusmn; 11.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.175\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAbbreviations: ROM = Range of Motion, HKA = Hip-Knee-Ankle, KSS= Knee Society Score, SD=Standard Deviation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOperative data\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMean operative time was significantly shorter for the UC group at 116.4 \u0026nbsp;\u0026plusmn; 10.7 min compared to 122.9 \u0026plusmn; 14 min for the PS group, p = 0.03.\u003c/p\u003e\n\u003cp\u003eBlood transfusion was required in two UC cases (6%) and in none of the PS cases (p = 0.163).\u003c/p\u003e\n\u003cp\u003eMean hospital stay was comparable, averaging 2.8 \u0026nbsp;\u0026plusmn; 1.8 days in the UC group and\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3.1 \u0026plusmn; 2.1 days in the PS group (p = 0.431).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunctional outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePostoperatively, UC and PS TKA patients showed significant improvements of walking distance, stair climbing ability, walking aids use and KSS function (all p\u0026lt;0.05).\u003c/p\u003e\n\u003cp\u003eWhen comparing the two groups, there was no significant difference in functional outcomes, except for better stair climbing for UC patients in Charnley A category (p=0.037) (Table 5).\u003c/p\u003e\n\u003cp\u003eKSS function scores were similar in Charnley A category (70.7 for UC vs. 64.2 for PS, p= 0.316), and in Charnley B category (57.4 for UC vs. 55 for PS, p=0.709) (Table 4).\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4: Comparison of functional outcomes between the two groups\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"99%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCharnley A category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=15)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=12)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking distance score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e32.7 \u0026plusmn; 8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e33.3 \u0026plusmn; 10.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.855\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStair climbing score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e38.7 \u0026plusmn; 7.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e31.7 \u0026plusmn; 9.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e0.037\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking aids use, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e2(13%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e2(17%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.809\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKSS function score (/100 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e70.7 \u0026plusmn; 13.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e64.2 \u0026plusmn; 19.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.316\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"4\" style=\"width: 100px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eCharnley B category\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=21)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=22)\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking distance score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e29 \u0026plusmn; 10.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e25.9 \u0026plusmn; 8.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.298\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eStair climbing score (/50 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e30 \u0026plusmn; 11.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e30.9 \u0026plusmn; 10.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.784\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eWalking aids use, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e7(33%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e7(32%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.916\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 53px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKSS function score (/100 points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 16px;\"\u003e\n \u003cp\u003e57.4 \u0026plusmn; 22.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 17px;\"\u003e\n \u003cp\u003e55 \u0026plusmn; 19.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 11px;\"\u003e\n \u003cp\u003e0.709\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAbbreviations: SD=Standard Deviation, KSS=Knee Society Score\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePostoperatively, pain intensity score, ROM, and KSS knee score showed significant improvements across both cohorts (all p\u0026lt;0.001).\u003c/p\u003e\n\u003cp\u003eThere was no significant difference between the UC and PS groups in pain intensity scores (43.6 \u0026plusmn; 5.3 for UC group vs. 41.3 \u0026plusmn; 7 for PS group, p=0.126) or average ROM (113.3\u0026deg; \u0026plusmn; 9.3 for UC TKA vs. 113.7\u0026deg; \u0026plusmn; 10.4 for PS TKA, p=0.884).\u003c/p\u003e\n\u003cp\u003eHowever, we noted better anteroposterior stability for PS implants, at 90\u0026deg; flexion, compared with UC TKA (p=0.045).\u003c/p\u003e\n\u003cp\u003eThe mean postoperative KSS knee score was 89.9 \u0026plusmn; 7.2 in the UC group compared with 86.4 \u0026plusmn; 9.9 in the PS group, showing a non-significant trend toward better results with the UC design (p=0.09) (Table 5).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5: comparison of clinical outcomes between the two groups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" colspan=\"2\" style=\"width: 47px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 21px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=36)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 20px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=34)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" colspan=\"2\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePain intensity score (/50points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e43.6 \u0026plusmn; 5.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e41.3 \u0026plusmn; 7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.296\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eROM (degrees \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e113.3\u0026deg; \u0026plusmn; 9.3\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e113.3\u0026deg; \u0026plusmn; 10.4\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.603\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eFlexion contracture, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e0\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e35(97%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e31(91%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.241\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u0026ge;5\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e3(9%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 32px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eAnteroposterior stability, n(%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e5-9mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e4(11%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.942\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 14px;\"\u003e\n \u003cp\u003e\u0026lt;5mm\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e32(89%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e34(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 47px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eKSS knee score (/100points \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 21px;\"\u003e\n \u003cp\u003e89.9 \u0026plusmn; 7.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 20px;\"\u003e\n \u003cp\u003e86.4 \u0026plusmn; 9.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.175\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAbbreviations: ROM = Range of Motion, HKA = Hip-Knee-Ankle, KSS= Knee Society Score, SD=Standard Deviation\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRadiological outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe mean postoperative HKA angle was 177.7\u0026deg; \u0026plusmn; 1.4\u0026deg; for UC group, and 177.2\u0026deg; \u0026plusmn; 2.3\u0026deg; for PS group (p=0.338).\u003c/p\u003e\n\u003cp\u003eNon-progressive radiolucent lines (RLLs) were most frequently identified in Tibial Zone 1 (medial plateau) on the anteroposterior radiographs. These were documented in 2 cases of the UC group and 4 cases of the PS group (Table 6).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6: Comparison of radiological outcomes between the two grouups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" colspan=\"2\" style=\"width: 301px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent (n=36)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized (n=34)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 76px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"2\" style=\"width: 301px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eHKA (degrees \u0026plusmn; SD)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 121px;\"\u003e\n \u003cp\u003e177.7\u0026deg; \u0026plusmn; 1.4\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 110px;\"\u003e\n \u003cp\u003e177.2\u0026deg; \u0026plusmn; 2.3\u0026deg;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.338\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" rowspan=\"5\" style=\"width: 181px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTibial radiolucent lines (Anteroposterior radiograph)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e34(94%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e27(80%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.080\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eZone 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e2(6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e4(11%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eZone 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eZone 1 + 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eZone 1 + 2 + 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" rowspan=\"4\" style=\"width: 181px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eTibial radiolucent lines (Lateral radiograph)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eNone\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e36(100%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e31(91%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" style=\"width: 76px;\"\u003e\n \u003cp\u003e0.091\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eZone 1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eZone 2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 120px;\"\u003e\n \u003cp\u003eZone 1 + 2 + 3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 121px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 110px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eAbbreviations: HKA = Hip-Knee-Ankle, SD=Standard Deviation\u003c/p\u003e\n\u003cp\u003eThere was a non-significant trend toward a lower incidence of tibial radiolucent lines in UC TKA compared to PS TKAs, in both anteroposterior (p=0.08) and lateral radiographs (p=0.091).\u003c/p\u003e\n\u003cp\u003eProgressive radiolucency that extended to all tibial zones was observed in one case, which belonged to the PS group. These findings were highly suggestive of aseptic implant loosening, and the patient subsequently underwent revision surgery.\u003c/p\u003e\n\u003cp\u003eThis was the only major complications recorded in our series. And the difference in complication rates did not reach statistical significance (p=0.486).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSatisfaction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOverall satisfaction was similar between the two groups (p=0.229), with 31% of UC and 26% of PS patients reporting very high satisfaction, and 61% of UC and 53% of PS patients describing themselves as satisfied (Table 7).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 7: comparison of satisfaction between the two groups\u003c/strong\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"100%\" class=\"fr-table-selection-hover\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd nowrap=\"\" style=\"width: 35px;\"\u003e\u003cbr\u003e\u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 27px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eUltra-congruent\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=36)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 25px;\"\u003e\n \u003cp\u003e\u003cstrong\u003ePosterior-stabilized\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e(n=34)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 11px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eP-value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eVery satisfied\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 27px;\"\u003e\n \u003cp\u003e11(31%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 25px;\"\u003e\n \u003cp\u003e9(26%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" style=\"width: 11px;\"\u003e\n \u003cp\u003e0.229\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eSatisfied\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 27px;\"\u003e\n \u003cp\u003e22(61%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 25px;\"\u003e\n \u003cp\u003e18(53%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eImproved\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 27px;\"\u003e\n \u003cp\u003e2(6%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 25px;\"\u003e\n \u003cp\u003e7(21%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 35px;\"\u003e\n \u003cp\u003e\u003cstrong\u003eDissatisfied\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 27px;\"\u003e\n \u003cp\u003e1(3%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd nowrap=\"\" style=\"width: 25px;\"\u003e\n \u003cp\u003e0(0%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Discussion","content":"\u003cp\u003eSeveral findings emerged from the analysis of our data. First, both UC and PS TKAs provided significant improvement in pain relief, ROM and limb alignment.\u003c/p\u003e\n\u003cp\u003eOur data further demonstrated that UC TKA provides functional, clinical and radiological outcomes equivalent to PS TKA, with less bone resection, shorter operative time (p=0.03), better stair climbing in Charnley A patients (p=0.037) and a non-significant trend toward fewer tibial radiolucent lines, at the cost of a decrease in anteroposterior stability, that did not adversely affect KSS scores or patient satisfaction.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePain intensity\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOur study found similar pain intensity scores between UC and PS TKA. Pain is the primary indicator of patient satisfaction and accounts for 50% of the KSS knee score [6]. However, its assessment remains inherently subjective and may be influenced by both physical and psychological factors.\u003c/p\u003e\n\u003cp\u003eOur findings align with the meta-analysis by Raja [8], which reported similar KSS pain scores between the UC and PS groups (p=0.15).\u003c/p\u003e\n\u003cp\u003eL\u0026uuml;tzner et al. [4] found no significant differences in pain outcomes at five years; however, at one and three years postoperatively, the Oxford Knee score (OKS) pain score was significantly better for UC patients. This suggests that, although pain outcomes are equivalent at mid-term follow-up, UC TKA may provide a faster recovery pattern compared with PS TKA.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRange of motion\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the present study, no significant difference in ROM was observed between the UC and PS TKA groups. Current literature remains divided regarding which design provides superior postoperative ROM.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA 2018 meta-analysis [9] concluded that the PS group achieved significantly greater ROM than the UC group. The underlying rationale for superior flexion in PS designs is attributed to femoral rollback: the physiological posterior translation of the femorotibial contact point during flexion, which prevents posterior impingement, thereby allowing deeper flexion\u0026nbsp;[10\u0026ndash;12]. Kinematic studies have demonstrated that the cam-post mechanism in PS TKA induces significantly more posterior rollback compared to the conforming geometry of UC TKA\u0026nbsp;[13\u0026ndash;15].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eConversely, a more recent 2021 systematic review and meta-analysis [8] found no statistically significant difference in postoperative ROM between the two designs.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe contradiction between studies showing significant kinematic advantages for PS TKA and those showing no difference in ROM suggests that other factors are highly influential. Soft tissue balancing, restoration of the joint line, and postoperative physiotherapy have a major impact on final ROM [4,13]. Furthermore, femoral external rotation is also crucial factor for maximum knee flexion [16]. Bae\u0026rsquo;s meta-analysis [9] showed that UC TKA had significantly more femoral external rotation compared to PS TKA. This enhanced rotational freedom may compensate for reduced rollback, explaining the equivalent ROM observed in several studies.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAnteroposterior stability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the present study, PS TKA demonstrated superior clinical anteroposterior stability at 90\u0026deg;\u0026nbsp;flexion compared to UC TKA (p=0.045).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eA meta-analysis by Wenzel et al. reported that PS TKAs achieve significantly better anteroposterior stability in deep flexion compared to UC designs [17].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHowever, the mechanism of constraint is flexion-dependent: according to Scott [18], the femoral cam in posterior-stabilized designs does not engage the polyethylene post until approximately 60\u0026deg; of flexion, whereas the highly conforming polyethylene insert with the anterior and posterior lips provides more consistent stability throughout the range of motion.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCorrespondingly, several studies have reported similar or superior anteroposterior stability for UC TKA in the 0\u0026ndash;30\u0026deg; flexion range, while PS TKA tends to demonstrate greater stability beyond 60\u0026deg; of flexion [13,18,19]. This is particularly relevant since most daily activities depend on knee stability from extension to mid-flexion rather than at 90\u0026deg; of flexion [15,20].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStair climbing\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn our study, Charnley A patients with UC TKA had significantly better stair climbing scores, compared to patients with PS TKA (p = 0.037).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFew studies detail the stair climbing subscore in their results. However, there is some evidence in literature to better outcomes for UC in activities with high patellofemoral load: L\u0026uuml;tzner\u0026rsquo;s RCT [4] reported significantly better OKS functional scores for UC implants at one and three years postoperatively. Specifically, UC designs outperformed PS designs in tasks with high patellofemoral load, such as rising from a chair (p=0.025) and kneeling (p=0.052) [4].\u003c/p\u003e\n\u003cp\u003eThese findings contrast with those of Sur et al. [21], who found no statistically significant differences between the two groups in KSS stair climbing scores at 5 years follow-up (p = 0.328).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eKnee Society Score\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn the present study, KSS functional scores were comparable between UC and PS TKA groups for both Charnley Category A (p = 0.316) and Category B patients (p = 0.709). These findings align with several meta-analyses [8,17] and randomized controlled trials\u0026nbsp;[14,15,18,22\u0026ndash;25]\u0026nbsp;that reported no mid-to-long-term functional differences between the designs.\u003c/p\u003e\n\u003cp\u003eHowever, some literature suggests transient functional advantages for the UC design. Carlson et al. [26] observed significantly higher KSS functional scores for UC implants at 6 months (p = 0.04), 1 year (p = 0.03), and 2 years (p = 0.04) postoperatively.\u0026nbsp;Notably, these differences equilibrated by the 5-year follow-up.\u003c/p\u003e\n\u003cp\u003eIn our cohort, there was a trend toward better KSS Knee score with UC TKA, compared to PS TKA, although this did not reach statistical significance (p=0.09).\u003c/p\u003e\n\u003cp\u003eThe predominant finding across multiple high-level studies is that the intrinsic kinematic differences between UC and PS implants do not translate into statistically significant differences in the overall KSS knee score:\u003c/p\u003e\n\u003cp\u003eWenzel\u0026lsquo;s 2023 systematic review and meta-analysis [17] showed that despite better anteroposterior stability and more femoral rollback of PS implants, there was no statistically significant difference in the KSS knee score between the UC and PS TKAs.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eRadiological outcomes, complications and revision rates\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOur findings showed a trend toward fewer radiolucent lines in the UC group compared to the PS group. A Meta-analysis by Tsai et al. [28] also reported fewer radiolucent lines in UC TKA compared to PS TKA. However, the difference did not reach statistical significance.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn theory, eliminating the PS tibial post removes a point of stress that could potentially generate polyethylene debris and micro-motion at the tibial component [28].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMoreover, the lower incidence of radiolucent lines in our UC group may be attributable to the bone-preserving nature of the design. By eliminating the femoral box cut, UC implants preserve intercondylar bone stock, maintaining cortical support and reducing stress at the bone-implant interface [29]. This bone-preserving approach also influences operative time, L\u0026uuml;tzner et al. [4] cited the intercondylar box preparation as a factor for the 10-minute increase in operative time for PS TKAs (p \u0026lt; 0.001). Our study showed similar results, with UC surgeries lasting 6.5 minutes shorter on average than PS procedures (p=0.03).\u003c/p\u003e\n\u003cp\u003eBeyond surgical time, the additional bone resection required for PS designs may impact blood loss. In an RCT of 111 patients, Scott et al. [48] observed a steeper postoperative hemoglobin decline in the PS group compared to UC group. While the overall decline was not statistically significant, the study did identify a significantly higher transfusion rate among male patients within the PS cohort (\u003cem\u003ep\u003c/em\u003e = 0.039)..\u003c/p\u003e\n\u003cp\u003eFurthermore, avoiding intercondylar bone resection offers a long-term advantage for younger patients, who may require revision surgery. Indeed, preserving bone stock often negates the need for complex augments and extensive bone grafts during revision surgery [30]. It also minimizes the risk of periprosthetic fractures during component removal and facilitates a more accurate restoration of the joint line in the revision setting [4].\u003c/p\u003e\n\u003cp\u003eMoreover, there is some evidence to lower revision rates with UC TKA: in his study of 67,523 primary TKA using the same Genesis II knee system with different inserts, Dalton [31] reported an 8.3% revision rate at 18 years for UC implants, compared with 8.9% for PS implants (8.9%), the difference was statistically significant (HR 1.19, 95% CI 1.08-1.31, p \u0026lt; 0.001).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSatisfaction\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOverall, 31% of UC and 26% of PS patients reported very high satisfaction, and 61% of UC and 53% of PS patients described themselves as satisfied. There was no significant difference between the two groups (p=0.229). Our findings are similar to Machihindra\u0026rsquo;s [32] results.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eKim et al. [15] compared UC and PS TKA within the same patients and found no difference in satisfaction, joint perception or side preference between the two knees.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy strengths\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo our knowledge, this study represents the first comparative analysis of ultra-congruent total knee arthroplasty in the MENA region. It provides valuable mid-term data from a region that is underrepresented in the arthroplasty literature. The consistency of our findings with international data strengthens the confidence in UC inserts as an alternative to PS inserts. Methodological bias was strictly controlled through independent assessment, as all clinical and radiographic data were collected by a single observer not involved in the surgical procedures. Furthermore, the restriction of this study to a single institution with a standardized surgical protocol and uniform operative conditions minimized technical confounding variables between the two statistically comparable groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStudy limitations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study has several limitations. First, the retrospective design inherently limits control over data collection and introduces potential selection bias, as the surgical rationale for choosing a UC versus a PS implant was not documented. Second, our sample size of 70 patients is relatively small, while it provided sufficient power to detect significant differences in surgical efficiency and reported outcomes, it remains underpowered to evaluate rare complications or long-term revision rates.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLarger randomized controlled trials with longer follow-up are needed to confirm the long-term equivalence of UC TKA to PS TKA in terms of patient-reported outcomes, and to determine whether the radiographic advantages suggested in our series translates into better survivorship.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eDespite the differences in kinematics, UC TKA provided equivalent mid-term outcomes to PS TKA, with less bone resection, less operative time and better stair climbing, at the cost of a minor increase in anteroposterior laxity that remained within acceptable limits.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAnd thus, we can safely recommend UC inserts as an alternative to PS designs, especially in young patient, where bone stock preservation is a priority.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eTKA\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eTotal Knee Arthroplasty\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003ePS\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePosterior-Stabilized\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eUC\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eUltra-congruent\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eBMI\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBody-Mass-Index\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eROM\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRange Of Motion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eHKA\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eHip-Knee-Ankle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eKSS\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eKnee Society Score\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eRLL\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eRadioLucent Lines\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eOKS\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eOxford Knee Score\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo funding was received for this study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors and Affiliations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u003csup\u003e1\u003c/sup\u003e\u003c/strong\u003e\u003cstrong\u003eMohamed Kassab Institute of Orthopedics, Manouba, Tunisia\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZied Masmoudi\u003csup\u003e\u0026nbsp;\u003c/sup\u003e; Sami Bahroun\u003csup\u003e\u0026nbsp;\u003c/sup\u003e; Mohamed Taghouti\u003csup\u003e\u0026nbsp;\u003c/sup\u003e; Maher Ben Thayer ; Mohamed Samir Daghfous\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003e\u0026sup2;Tunis El Manar University, Tunisia\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZied Masmoudi\u003csup\u003e\u0026nbsp;\u003c/sup\u003e; Sami Bahroun\u003csup\u003e\u0026nbsp;\u003c/sup\u003e; Mohamed Taghouti\u003csup\u003e\u0026nbsp;\u003c/sup\u003e; Maher Ben Thayer;\u003csup\u003e\u0026nbsp;\u003c/sup\u003e Sofiane Masmoudi; Mohamed Samir Daghfous\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eContributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eZ.M. and S.B. contributed to the study conception and design. M.T. and M.B.T. collected and analyzed the data. S.M performed the statistical analysis and interpreted the results. M.S.D. supervised the project and provided critical revisions. Z.M. and S.B. wrote the main manuscript text. All authors reviewed and approved the final\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003emanuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorresponding author\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eCorrespondence to Zied Masmoudi.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis retrospective study was reviewed and approved by the ethics committee of the Mohamed Kassab Institute of Orthopedics (approval reference: IMKO-CE-2023-131).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe requirement for written informed consent was waived because only de-identified data routinely collected in clinical practice were analyzed.\u003c/p\u003e\n\u003cp\u003eAll methods were performed in accordance with the principles of the Declaration of Helsinki.\u0026nbsp;\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\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eHeidari B. Knee osteoarthritis prevalence, risk factors, pathogenesis and features: Part I. Casp J Intern Med. 2011;2(2):205\u0026ndash;12.\u003c/li\u003e\n \u003cli\u003eLi E, Tan J, Xu K, Pan Y, Xu P. Global burden and socioeconomic impact of knee osteoarthritis: a comprehensive analysis. Front Med. 2024 May 16;11:1323091.\u003c/li\u003e\n \u003cli\u003eDeFrance MJ, Scuderi GR. Are 20% of Patients Actually Dissatisfied Following Total Knee Arthroplasty? A Systematic Review of the Literature. J Arthroplasty. 2023 Mar;38(3):594\u0026ndash;9.\u003c/li\u003e\n \u003cli\u003eL\u0026uuml;tzner J, Beyer F, L\u0026uuml;tzner C, Riedel R, Tille E. Ultracongruent insert design is a safe alternative to posterior cruciate-substituting total knee arthroplasty: 5-year results of a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2022 Sept;30(9):3000\u0026ndash;6.\u003c/li\u003e\n \u003cli\u003eEwald FC. The Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System: Clin Orthop. 1989 Nov;248:9-12.\u003c/li\u003e\n \u003cli\u003eInsall JN, Dorr LD, Scott RD, Norman W. Rationale, of The Knee Society Clinical Rating System: Clin Orthop. 1989 Nov;248:13-14.\u003c/li\u003e\n \u003cli\u003eCharnley J. The long-term results of low-friction arthroplasty of the hip performed as a primary intervention. J Bone Joint Surg Br. 1972 Feb;54-B(1):61\u0026ndash;76.\u003c/li\u003e\n \u003cli\u003eS.Raja B, Gowda AKS, Ansari S, Choudhury AK, Kalia RB. Comparison of Functional Outcomes, Femoral Rollback and Sagittal Stability of Anterior-Stabilized Versus Posterior-Stabilized Total Knee Arthroplasty: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Indian J Orthop. 2021 Aug 23;55(5):1076\u0026ndash;86.\u003c/li\u003e\n \u003cli\u003eBae JH, Yoon JR, Sung JH, Shin YS. Posterior-stabilized inserts are preferable to cruciate-substituting ultracongruent inserts due to more favourable kinematics and stability. Knee Surg Sports Traumatol Arthrosc. 2018 Nov;26(11):3300\u0026ndash;10.\u003c/li\u003e\n \u003cli\u003eEwald FC, Jacobs MA, Miegel RE, Walker PS, Poss R, Sledge CB. Kinematic total knee replacement. J Bone Joint Surg Am. 1984 Sept;66(7):1032\u0026ndash;40.\u003c/li\u003e\n \u003cli\u003eAndriacchi TP, Galante JO. Retention of the posterior cruciate in total knee arthroplasty. J Arthroplasty. 1988;3 Suppl:S13-19.\u003c/li\u003e\n \u003cli\u003eFreeman M a. R, Pinskerova V. The movement of the normal tibio-femoral joint. J Biomech. 2005 Feb;38(2):197\u0026ndash;208.\u003c/li\u003e\n \u003cli\u003eFritzsche H, Beyer F, Postler A, L\u0026uuml;tzner J. Different intraoperative kinematics, stability, and range of motion between cruciate-substituting ultracongruent and posterior-stabilized total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2018 May 1;26(5):1465\u0026ndash;70.\u003c/li\u003e\n \u003cli\u003eL\u0026uuml;tzner J, Beyer F, Dexel J, Fritzsche H, L\u0026uuml;tzner C, Kirschner S. No difference in range of motion between ultracongruent and posterior stabilized design in total knee arthroplasty: a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc. 2017 Nov;25(11):3515\u0026ndash;21.\u003c/li\u003e\n \u003cli\u003eKim YB, Choi HS, Kang EM, Park S, Seo GW, Chun DI, et al. Trends of Total Knee Arthroplasty According to Age Structural Changes in Korea from 2011 to 2018. Int J Environ Res Public Health. 2021 Dec 20;18(24):13397.\u003c/li\u003e\n \u003cli\u003eDennis DA, Komistek RD, Mahfouz MR, Walker SA, Tucker A. A multicenter analysis of axial femorotibial rotation after total knee arthroplasty. Clin Orthop. 2004 Nov 1;(428):180\u0026ndash;9.\u003c/li\u003e\n \u003cli\u003eWenzel AN, Hasan SA, Chaudhry YP, Mekkawy KL, Oni JK, Khanuja HS. Ultracongruent Designs Compared to Posterior-Stabilized and Cruciate-Retaining Tibial Inserts \u0026ndash; What Does the Evidence Tell Us? A Systematic Review and Meta-Analysis. J Arthroplasty. 2023 Dec 1;38(12):2739-2749.e7.\u003c/li\u003e\n \u003cli\u003eScott DF. Prospective Randomized Comparison of Posterior-Stabilized Versus Condylar-Stabilized Total Knee Arthroplasty: Final Report of a Five-Year Study. J Arthroplasty. 2018 May;33(5):1384\u0026ndash;8.\u003c/li\u003e\n \u003cli\u003eRoberti di Sarsina T, Alesi D, Di Paolo S, Zinno R, Pizza N, Marcheggiani Muccioli GM, et al. In vivo kinematic comparison between an ultra-congruent and a posterior-stabilized total knee arthroplasty design by RSA. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2022 Aug;30(8):2753\u0026ndash;8.\u003c/li\u003e\n \u003cli\u003eDavies AP. Rating systems for total knee replacement. The Knee. 2002 Dec;9(4):261\u0026ndash;6.\u003c/li\u003e\n \u003cli\u003eSur YJ, Koh IJ, Park SW, Kim HJ, In Y. Condylar-Stabilizing Tibial Inserts Do Not Restore Anteroposterior Stability After Total Knee Arthroplasty. J Arthroplasty. 2015 Apr 1;30(4):587\u0026ndash;91.\u003c/li\u003e\n \u003cli\u003eKim TW, Lee SM, Seong SC, Lee S, Jang J, Lee MC. Different intraoperative kinematics with comparable clinical outcomes of ultracongruent and posterior stabilized mobile-bearing total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc Off J ESSKA. 2016 Sept;24(9):3036\u0026ndash;43.\u003c/li\u003e\n \u003cli\u003eAkti S, Karakus D, Sezgin EA, Cankaya D. No differences in clinical outcomes or isokinetic performance between cruciate-substituting ultra-congruent and posterior stabilized total knee arthroplasties: a randomized controlled trial. Knee Surg Sports Traumatol Arthrosc. 2021;29(10):1795.\u003c/li\u003e\n \u003cli\u003eJang SW, Kim MS, Koh IJ, Sohn S, Kim C, In Y. Comparison of Anterior-Stabilized and Posterior-Stabilized Total Knee Arthroplasty in the Same Patients: A Prospective Randomized Study. J Arthroplasty. 2019 Aug;34(8):1682\u0026ndash;9.\u003c/li\u003e\n \u003cli\u003eLaskin RS, Maruyama Y, Villaneuva M, Bourne R. Deep-dish congruent tibial component use in total knee arthroplasty: a randomized prospective study. Clin Orthop. 2000 Nov;(380):36\u0026ndash;44.\u003c/li\u003e\n \u003cli\u003eCarlson BJ, Jones BK, Scott DF. A prospective comparison of total knee arthroplasty using ultra-congruent, condylar-stabilizing, and posterior-stabilized devices implanted with kinematic alignment: better 2-year outcomes with ultra-congruent. Knee Surg Sports Traumatol Arthrosc. 2023;31(3):1026\u0026ndash;33.\u003c/li\u003e\n \u003cli\u003eRosa AD. Comparison of ultra-congruent anterior-stabilized vs. a posterior cruciate substituting total knee arthroplasty for osteoarthritis with severe varus knee deformity: comparable 2 year outcomes with two design. Eur Rev Med Pharmacol Sci. 2023 Sep;27(17):7968-76.\u003c/li\u003e\n \u003cli\u003eTsai YL, Tsai SHL, Lin CH, Lin CR, Hu CC. The Effect of Congruent Tibial Inserts in Total Knee Arthroplasty: A Network Meta-Analysis of Randomized Controlled Trials. Life. 2023 Sept;13(9):1942.\u003c/li\u003e\n \u003cli\u003eRajguhan TV, Vanchi PK, Prashanth KRT, Veeraraghavan RR, Murugesan MK. Inserting the best knee: A short-term analysis of posterior stabilized versus cruciate substituting ultracongruent tibial inserts for total knee replacement. J Musculoskelet Surg Res. 2023 July 31;7(3):180\u0026ndash;5.\u003c/li\u003e\n \u003cli\u003eKurtz WB, Slamin JE, Doody SW. Bone Preservation in a Novel Patient Specific Total Knee Replacement. Reconstr Rev. 2016 Apr 26;6(1):133\u0026ndash;133.\u003c/li\u003e\n \u003cli\u003eDalton P, Holder C, Rainbird S, Lewis PL. Survivorship Comparisons of Ultracongruent, Cruciate-Retaining and Posterior-Stabilized Tibial Inserts Using a Single Knee System Design: Results From the Australian Orthopedic Association National Joint Replacement Registry. J Arthroplasty. 2022 Mar;37(3):468\u0026ndash;75.\u003c/li\u003e\n \u003cli\u003eMachhindra MV, Kang JY, Kang YG, Chowdhry M, Kim TK. Functional Outcomes of a New Mobile-Bearing Ultra-Congruent TKA System: Comparison With the Posterior Stabilized System. J Arthroplasty. 2015 Dec;30(12):2137\u0026ndash;42.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":true,"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":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Osteoarthritis, Knee, Arthroplasty, Replacement, Knee, Ultra-congruent, Posterior-stabilized, Patient satisfaction, Treatment outcome","lastPublishedDoi":"10.21203/rs.3.rs-8682901/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8682901/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTotal knee arthroplasty (TKA) is an effective treatment for knee osteoarthritis, yet one in five patients remain dissatisfied after surgery. Implant design is thought to be a contributing factor to this dissatisfaction. Posterior-stabilized (PS) TKA rely on a cam-post mechanism for stability, but this design has been associated with specific complications. Ultra-congruent (UC) TKA rely on highly-conforming polyethylene instead.\u003c/p\u003e\n\u003cp\u003eThe aim of this study was to describe and compare the mid-term functional, clinical and radiological outcomes of the UC and PS TKA, in order to determine whether UC implants can be recommended as a safe alternative to the well-established PS implants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eThis retrospective study included 70 primary TKAs (36 UC, 34 PS) performed at the Adults B department, of the Mohamed Kassab Institute of orthopedics, between 2013 and 2020, with a minimum follow-up of 3 years (mean 4.7 years). Pre- and postoperative assessment included functional, clinical and radiological outcomes of the Knee Society Score (KSS). Operative time and hospital stay were noted, as well as complications and overall satisfaction.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003ePreoperative demographic, functional, clinical and radiographic parameters were comparable between groups. Operative time was shorter with UC (116.4 vs 122.9 minutes; p=0.03). Postoperatively, both designs showed significant improvements in pain, range of motion, limb alignment, KSS knee and function scores (all p\u0026lt;0.001). Functional outcomes were similar for UC and PS, except for better\u003cstrong\u003e \u003c/strong\u003estair-climbing in Charnley A patients with UC (p=0.037). Pain, range of motion and KSS scores did not differ significantly. PS knees showed better anteroposterior stability (p=0.045). There was a trend to fewer radiolucent lines with UC (p=0.08). Overall satisfaction was high and comparable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion\u003c/strong\u003e:\u003c/p\u003e\n\u003cp\u003eAt mid-term follow-up, UC TKA provided functional, clinical and radiological outcomes equivalent to PS TKA, with less bone resection, shorter operative time, better stair climbing in Charnley A patients and a tendency toward fewer tibial radiolucent lines, at the cost of a small increase in anteroposterior laxity that remained within acceptable limits. UC inserts can be recommended as a safe and effective alternative to PS designs.\u003c/p\u003e","manuscriptTitle":"Mid-term outcomes of ultra-congruent total knee arthroplasty: a comparison with the posterior-stabilized implants","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-03 11:19:26","doi":"10.21203/rs.3.rs-8682901/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewersInvited","content":"","date":"2026-03-23T10:34:33+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-26T05:25:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-26T05:24:39+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Orthopaedic Surgery and Research","date":"2026-01-24T00:03:01+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-orthopaedic-surgery-and-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"josr","sideBox":"Learn more about [Journal of Orthopaedic Surgery and Research](http://josr-online.biomedcentral.com)","snPcode":"13018","submissionUrl":"https://submission.nature.com/new-submission/13018/3","title":"Journal of Orthopaedic Surgery and Research","twitterHandle":"@MSKmedBMC","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"a10d14f3-7742-40c1-8f55-dda2c8bf3ced","owner":[],"postedDate":"April 3rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-03T11:19:26+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-03 11:19:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8682901","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8682901","identity":"rs-8682901","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}