Limited ability of coronal alignment parameters to assess rotational alignment in patients with varus knee osteoarthritis: a cross-sectional study

Limited ability of coronal alignment parameters to assess rotational alignment in patients with varus knee osteoarthritis: a cross-sectional study | 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 Limited ability of coronal alignment parameters to assess rotational alignment in patients with varus knee osteoarthritis: a cross-sectional study Haoshen Wu, Zian Zhang, Fan Chen, Wenzhe Wang, Chaoqun Yu, Nanyu Pang, and 2 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9381432/v1 This work is licensed under a CC BY 4.0 License Status: Under Revision Version 1 posted 11 You are reading this latest preprint version Abstract Purpose This study aimed to investigate whether rotational alignment parameters vary across different severities of varus deformity and to examine the correlation between coronal and rotational alignment parameters in end-stage varus knee osteoarthritis (KOA). Methods We performed a retrospective study on 315 lower extremities with end-stage KOA. The lower extremities were categorized into the mild varus group (n = 141) and the severe varus (n = 174) group according to mechanical hip-knee-ankle angle (mHKA). Coronal alignment parameters were measured on standing full-limb radiographs, including the mHKA, lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA). Rotational alignment parameters were measured on computed tomography (CT), including the femoral anteversion angle (FAA), condylar twist angle (CTA), and tibial torsion angle (TTA). Results We found no significant differences in any lower-limb rotational parameters between the mild varus and severe varus groups. Correlation analysis revealed that only TTA was significantly correlated with coronal alignment parameters, which was associated with MPTA in the mild varus group (r = 0.200, p = 0.020), mHKA in the severe varus group (r = 0.239, p = 0.001), and mHKA in the entire varus cohort (r = 0.118, p = 0.036). Conclusion The assessment of lower limb coronal alignment has limited ability to evaluate rotational alignment in patients with end-stage varus knee osteoarthritis. Therefore, surgeons should carefully evaluate rotational alignment both preoperatively and intraoperatively to identify patients with rotational abnormalities. Total knee arthroplasty Varus deformity Rotational alignment Coronal alignment Osteoarthritis Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Rotational alignment is a challenge for total knee arthroplasty (TKA). During the progression of knee osteoarthritis (KOA), torsional relationships between the hip and ankle relative to the knee may change [ 1 – 3 ]. Previous studies have demonstrated that rotational deformities of the femur and tibia can result in knee pain, patellar instability, and abnormal gait patterns [ 4 – 8 ]. Furthermore, rotational deformities of the lower extremity may contribute to component malrotation. Malrotation of femoral and tibial components often impairs tibiofemoral kinematics, thereby reducing functional scores and patient satisfaction [ 9 – 12 ]. Therefore, accurate assessment of rotational alignment parameters is essential for achieving optimal TKA outcomes. Rotation alignment parameters have traditionally been evaluated using computed tomography (CT) imaging. However, the absence of preoperative CT assessment in most TKA cases and the lack of accurate intraoperative measurement techniques render the identification of individuals with rotational abnormalities challenging. Coronal radiographs offer a simple, accurate, and cost-effective method for assessing the severity of varus and valgus deformities in patients with knee osteoarthritis. Previous studies have demonstrated significant correlations between rotational parameters, including the femoral anteversion angle (FAA), condylar twist angle (CTA), and tibial torsion angle (TTA), and changes in coronal alignment from varus to valgus [ 13 , 14 ]. These findings provide a basis for preoperative identification of patients with abnormal rotational parameters and for intraoperative adjustment of component rotation, which is of considerable importance for improving surgical precision, optimizing implant positioning, reducing postoperative complications, and enhancing functional recovery and patient satisfaction. These rotational parameters differ between patients with varus and valgus knees [ 13 , 14 ]. However, Asian patients with KOA predominantly present with varus deformity [ 15 , 16 ]. Given the distinct pathological mechanisms underlying varus and valgus knees in KOA, the relationship between rotational and coronal alignment parameters may not be applicable to patients with varus deformity. Patients with varying degrees of varus deformity may exhibit similar rotational parameters due to shared pathological processes, which could compromise the identification of individuals with abnormal lower limb rotation. We hypothesized that coronal alignment parameters would not reflect variations in rotational alignment among patients with varus KOA. The present study investigates whether rotational alignment parameters differ across patients with varying severities of varus deformity. Additionally, we examined whether coronal alignment parameters, including the mechanical hip–knee–ankle angle (mHKA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA), correlate with rotational alignment parameters, including FAA, CTA, and TTA, in patients with varus KOA. Materials and methods Study population We conducted a retrospective, observational, and single-center study of 315 total knee arthroplasties (TKAs) in 290 patients (Fig. 1 ). Patients who underwent TKA between December 2023 and June 2025 were assessed for eligibility. The inclusion criteria were cases that presented with the end-stage of KOA, and had preoperative standing full-limb anteroposterior radiographs along with axial CT scans. The exclusion criteria were preoperative valgus alignment of the lower extremity, rheumatoid arthritis, flexion contracture > 10°, and a previous history of lower extremity fracture or surgery. All cases were divided into two groups based on the degree of preoperative varus deformity. The cases with 0° ≤ varus < 10° were assigned to the mild varus group, and the cases with 10° ≤ varus were assigned to the severe varus group. The demographic data and preoperative angles of these subjects are summarised in Table 1 . Table 1 Demographic characteristics and lower limb alignment parameters of patients stratified by varus severity Parameters Mild varus group (n = 141) Severe varus group (n = 174) P value 0° ≤ varus < 10° 10° ≤ varus Age (years) 67.6 ± 5.8 67.5 ± 5.6 0.703 Sex (men : women) 33 : 108 41 : 133 0.974 Height (cm) 162.0 ± 7.1 162.1 ± 7.5 0.861 Weight (kg) 72.2 ± 11.2 73.9 ± 11.4 0.176 BMI (kg/m 2 ) 27.5 ± 3.6 28.0 ± 3.4 0.280 mHKA (°) 173.4 ± 2.4 166.1 ± 3.0 < 0.001 LDFA (°) 87.9 ± 2.2 90.1 ± 2.3 < 0.001 MPTA (°) 85.7 ± 2.0 83.2 ± 2.3 < 0.001 FAA (°) 15.1 ± 8.8 16.8 ± 8.9 0.081 CTA (°) 5.8 ± 2.2 5.6 ± 2.1 0.493 TTA (°) 25.0 ± 7.7 25.4 ± 7.4 0.593 Abbreviation: BMI = body mass index; mHKA = mechanical hip-knee-ankle angle; LDFA = lateral distal femoral angle; MPTA = medial proximal tibial angle; FAA = femoral anteversion angle; CTA = condylar twisting angle; TTA = tibial torsion angle Imaging techniques Axial CT (SOMATOM® Perspective, Siemens Healthcare GmbH, Erlangen, Germany) was used to acquire simultaneous axial images of the hip, knee, and ankle joints. The lower extremities of patients were fixed with a cylindrical metal rod in a state of neutral rotation in a supine position to obtain the CT scan[ 17 ]. Multislice CT images (130 keV, 170 mA) of the whole lower extremity with multiplanar reconstruction (slice thickness of 1.00 mm; reconstruction interval of 1.00 mm) were also obtained. Standing full-limb anteroposterior radiographs were obtained using an X-ray machine (Philips SRO 33100, Philips, Eindhoven, The Netherlands) at a source-to-image distance of 180 cm. To ensure the authenticity of the radiographs, all the imaging procedures were performed in strict accordance with the following standardized protocol. For standing full-limb anteroposterior radiographs, patients were positioned upright with the back against the detector, knees fully extended, feet shoulder-width apart, and internally rotated approximately 15°, ensuring one-third overlap of the fibular head with the tibia and anterior orientation of the patellae. Measurements All radiographs were digitally obtained by the Centricity™ universal viewer zero footprint. The coronal parameters, including mHKA, LDFA, and MPTA, were shown in Fig. 2 . All the coronal parameters were measured in standing full-limb anteroposterior radiographs. The mHKA was defined as a medial angle formed between femoral mechanical axis and tibial mechanical axis. The LDFA was defined as a lateral angle formed between femoral mechanical axis and the distal articular surface of the femoral condyles. The MPTA was defined as a medial angle formed between tibial mechanical axis and the proximal articular surface of the tibial platform. The varus deformity angle was calculated as 180° minus the mHKA. The rotational parameters, including femoral anteversion angle (FAA), condylar twisting angle CTA, and tibial torsion angle (TTA), were shown in Fig. 3 . All the coronal parameters were measured on axial CT images. The FAA was measured by the medial angle formed between the femoral neck axis and the posterior condylar line (PCL) [ 18 ]. Femoral anteversion was defined as a positive value. The CTA was measured by the medial angle formed between the PCL and the clinical transepicondylar axis (cTEA) [ 18 ]. The relative internal rotation of the PCL with respect to the cTEA was defined as a positive value. The TTA was measured by the lateral angle formed between the proximal and the distal tibia axis [ 19 ]. Relative internal rotation of the proximal tibia with respect to the distal tibia was defined as a positive value. Statistical analysis All statistical analyses were conducted using RStudio software (version 4.4.1), with p < 0.05 considered statistically significant. The Shapiro-Wilk test was conducted for continuous variables to evaluate the normality of the data. For two independent groups, a t-test was used to compare means when the data were normally distributed, whereas the Wilcoxon rank-sum test was applied when the data did not follow a normal distribution. The chi-square test was used to compare categorical variables between two independent groups. Spearman correlation analysis was utilized to evaluate the statistical significance of the association between the coronal parameters and the rotational parameters of the lower extremity in different varus groups. Intraclass correlation coefficients (ICCs) were employed to assess the intra-observer and inter-observer reliabilities of the radiographic measurement techniques. Two independent observers repeated the measurements twice, separated by a two-week interval. The ICCs for both intra-observer and inter-observer evaluations demonstrated excellent consistency (> 0.8). Results A total of 315 TKAs were enrolled and eligible for the study. According to the varus deformity angle, 141 TKAs and 174 TKAs were classified into the mild varus and severe varus groups, respectively. The mean age of the total varus group was 67.5 ± 5.7 years, the mean height was 162.1 ± 7.3, and the mean weight was 73.1 ± 11.3. The cases included 241 (76.5%) women and 74 (23.5%) men. There was a significant difference (p < 0.001) in all the coronal parameters between the mild varus and severe varus groups (Table 1 ). The mean mHKA was 173.4° ± 2.4° in the mild varus group, and 166.1° ± 3.0° in the severe varus group. The mean LDFA was 87.9° ± 2.2° in the mild varus group, and 90.1° ± 2.3° in the severe varus group. The mean MPTA was 85.7° ± 2.0° in the mild varus group, and 83.2° ± 2.3° in the severe varus group. However, no significant differences (p > 0.05) in any rotational parameters were observed between the mild varus and severe varus groups (Table 1 ). The mean FAA was 15.1° ± 8.8° in the mild varus group, and 16.8° ± 8.9° in the severe varus group. The mean CTA was 5.8° ± 2.2° in the mild varus group, and 5.6° ± 2.1° in the severe varus group. The mean TTA was 25.0° ± 7.7° in the mild varus group, and 25.4° ± 7.4° in the severe varus group. Correlation analysis was performed to evaluate the relationships between the coronal parameters and the rotational parameters. Neither FAA nor CTA was significantly associated with mHKA or LDFA in any of the varus groups. In the total varus group, only TTA was significantly associated with MPTA (r = 0.118, p = 0.036) (Table 2 ). In the mild varus group, only TTA was significantly associated with MPTA (r = 0.200, p = 0.020) (Table 3 ). In the severe varus group, only TTA was significantly associated with mHKA (r = 0.239, p = 0.001) (Table 3 ). The scatter plots and regression lines for the relationship between coronal and rotational alignment parameters are presented in Fig. 4 . Table 2 Correlation analysis between coronal alignment parameters and rotational alignment parameters across the entire varus cohort Rotational parameter Coronal parameter Correlation coefficient P value FAA mHKA −0.094 0.095 CTA mHKA 0.053 0.348 TTA mHKA 0.014 0.804 FAA LDFA 0.014 0.797 CTA LDFA −0.090 0.111 TTA MPTA 0.118 0.036 Abbreviation: FAA = femoral anteversion angle; CTA = condylar twisting angle; TTA = tibial torsion angle; mHKA = mechanical hip-knee-ankle angle; LDFA = lateral distal femoral angle; MPTA = medial proximal tibial angle Table 3 Subgroup correlation analysis between coronal and rotational alignment parameters stratified by varus severity Rotational parameter Coronal parameter Mild varus group (0° ≤ varus < 10°, n = 141) Severe varus group (10° ≤ varus, n = 174) Correlation coefficient P value Correlation coefficient P value FAA mHKA 0.116 0.171 −0.128 0.091 CTA mHKA −0.095 0.265 0.133 0.080 TTA mHKA −0.078 0.356 0.239 0.001 FAA LDFA −0.020 0.818 −0.029 0.705 CTA LDFA −0.058 0.493 −0.134 0.079 TTA MPTA 0.200 0.020 0.125 0.100 Abbreviation: FAA = femoral anteversion angle; CTA = condylar twisting angle; TTA = tibial torsion angle; mHKA = mechanical hip-knee-ankle angle; LDFA = lateral distal femoral angle; MPTA = medial proximal tibial angle Discussion This study investigated the relationship between coronal alignment parameters and rotational alignment parameters in patients with varus knee osteoarthritis. Among the 315 TKAs included in the present study, the varus knee deformity measured a mean of 6.6° in the mild varus group and 13.9° in severe cases (p < 0.001). However, there were no statistically significant differences in the rotational angles (FAA, CTA, and TTA) between patients with mild varus deformity and those with severe varus deformity. Furthermore, femoral rotational alignment parameters (FAA and CTA) had no significant correlations with mHKA and LDFA. Notably, we found significant correlations between both mHKA and MPTA and the tibial rotational alignment parameter (TTA). There are differences in rotational alignment between patients with varus and valgus deformities. Chang et al. [ 13 ] reported that the mean rotational alignment parameters in patients with valgus deformities (FAA = 16.7°, CTA = 10.2°, TTA = 32.6°) were higher than those in patients with varus deformities (FAA = 10.9°, CTA = 6.6°, TTA = 22.6°). Similarly, León-Muñoz et al. [ 14 ] reported that the mean rotational alignment parameters in valgus deformities (FAA = 12.1°; CTA = 6.4°; TTA = 24.6°) were higher than those in patients with varus deformities (FAA = 10.8°; CTA = 5.4°; TTA = 18.6°). Adjusting the prosthetic rotational alignment based on the preoperative deformity type can result in satisfactory clinical outcomes in TKA [ 20 ]. However, there is no consensus on whether prosthetic rotation should be adjusted based on the severity of varus deformity. Yoon et al. [ 21 ] suggest that prosthetic rotation should be adjusted to the degree of varus deformity in knee varus patients. However, previous studies demonstrated no significant differences in postoperative functional scores or complication rates between mild and severe varus deformity patients [ 22 , 23 ]. Furthermore, Oh et al. [ 24 ] confirmed that the long-term survival in TKAs had no significant difference in different degrees of preoperative varus deformity. Our study indicated that no statistical difference was found between the mild and severe varus groups in terms of rotational profiles. Consequently, we do not recommend using the severity of varus deformity to guide intraoperative prosthetic rotational alignment. Malrotation of femoral components remains a major cause of early TKA revision [ 25 ]. It has been shown that axial malrotation of femoral components can lead to postoperative pain, patellofemoral maltracking or instability, accelerated wear, or implant loosening [ 26 , 27 ]. Luyckx et al. [ 28 ] found that for each 1° increase in coronal alignment from varus to valgus, the posterior condylar angle increased by 0.1°. However, we did not find a significant correlation between CTA and mHKA or LDFA in varus patients. Although our study shows no significant correlation between FAA and mHKA or LDFA, decreased femoral anteversion increases hip external rotation and toe-out gait [ 29 ]. Although the FAA does not show a significant correlation with mHKA and LDFA, decreased femoral anteversion increases hip external rotation and toe-out gait. Additionally, the femoral distal shows a considerable individual variability in the rotational alignment [ 30 ]. To improve femoral prosthetic rotation accuracy, surgeons should consider anatomical variations and perform additional measurements preoperatively and intraoperatively. Excessive internal rotation of the tibial component in TKA is a widely recognized risk factor for postoperative pain and inferior functional outcomes. Nicoll and Rowley [ 31 ] reported that more than half of the 740 consecutive TKA cases who experienced postoperative pain had excessive internal rotation of the tibial component. Similarly, Barrack et al. [ 32 ] reported that patients who presented with anterior knee pain exhibited an average internal rotation of the tibial component of 6.2°, compared with only 0.4° in the asymptomatic control group. Our study found that in all varus patients, the internal rotation of the proximal tibia relative to the distal tibia was significantly associated with a decrease in MPTA. However, in patients with severe varus deformity, the internal rotation of the proximal tibia relative to the distal tibia was significantly associated with a decrease in mHKA, but not with a decrease in MPTA. Therefore, in patients with varus knee osteoarthritis, surgeons need to carefully assess tibial rotation and avoid excessive internal rotation of the tibial component. This study had several limitations. First, our study included Asian patients with females predominating. A previous study showed that anatomic torsional parameters vary across races [ 33 ]. Our results should be interpreted with caution when extrapolated to populations with different racial or sex distributions. Second, this study evaluated lower-limb rotational profiles using CT, which provides a static rather than a dynamic assessment. As a result, soft-tissue conditions that may influence dynamic limb alignment were not captured. Third, articular cartilage erosion can affect rotational parameters in KOA patients undergoing TKA. While cartilage status was not explicitly analyzed, all participants were in the end-stage of KOA requiring TKA, indicating that the risk of bias was likely minimal. Finally, this study only focused on patients with varus osteoarthritis. The coronal and axial alignment relationships in patients with varying degrees of valgus deformity require further investigation in future studies. Finally, this study lacked a clinical outcome. Conclusion The assessment of lower limb coronal alignment has limited ability to evaluate rotational alignment in patients with end-stage varus knee osteoarthritis. Therefore, surgeons should carefully evaluate rotational alignment both preoperatively and intraoperatively to identify patients with rotational abnormalities. Abbreviations KOA knee osteoarthritis mHKA mechanical hip–knee–ankle angle LDFA lateral distal femoral angle MPTA medial proximal tibial angle TKA total knee arthroplasty CT computed tomography FAA femoral anteversion angle CTA condylar twist angle TTA tibial torsion angle TKAs total knee arthroplasties PCL posterior condylar line cTEA clinical transepicondylar axis ICCs intraclass correlation coefficients Declarations Ethics approval and consent to participate This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of the Affiliated Hospital of Qingdao University (Project ID: QYFY WZLL 30614). Informed consent was obtained from all participants. Consent for publication Not applicable. Data availability The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request. Conflict of interest The authors declare no competing interests. Funding The authors declare that no funds, grants, or other support were received during the preparation of this manuscript. Author Contributions H.W. and Z.Z. wrote the paper and edited the manuscript. N.P. and F.M. collected the data. F.C. and W.W. measured the imaging parameters. C.Y. performed all the statistical analysis. H.Z. designed the whole study and revised the paper. All authors have read and approved the final manuscript. Acknowledgements The authors thank all their colleagues for their kind help and all patients for their cooperation with our work. References Yagi T, Sasaki T. Tibial torsion in patients with medial-type osteoarthritic knee. Clin Orthop Relat Res 1986(213):177–82. Eckhoff DG, Kramer RC, Alongi CA, VanGerven DP. Femoral anteversion and arthritis of the knee. J Pediatr Orthop. 1994;14(5):608–10. 10.1097/01241398-199409000-00010 . Takai S, Sakakida K, Yamashita F, Suzu F, Izuta F. Rotational alignment of the lower limb in osteoarthritis of the knee. 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Cite Share Download PDF Status: Under Revision Version 1 posted Editorial decision: Revision requested 13 May, 2026 Reviews received at journal 10 May, 2026 Reviews received at journal 05 May, 2026 Reviewers agreed at journal 19 Apr, 2026 Reviewers agreed at journal 19 Apr, 2026 Reviewers agreed at journal 16 Apr, 2026 Reviewers invited by journal 15 Apr, 2026 Editor invited by journal 14 Apr, 2026 Editor assigned by journal 13 Apr, 2026 Submission checks completed at journal 13 Apr, 2026 First submitted to journal 10 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-9381432","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":626830606,"identity":"0e980d04-3aa8-4b0c-a26f-c1c833a30a5c","order_by":0,"name":"Haoshen Wu","email":"","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Haoshen","middleName":"","lastName":"Wu","suffix":""},{"id":626830607,"identity":"6bf4fac2-8807-4d43-83c2-180562b88498","order_by":1,"name":"Zian Zhang","email":"","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Zian","middleName":"","lastName":"Zhang","suffix":""},{"id":626830610,"identity":"36424ba3-c54a-4bdd-8c51-9edac3269432","order_by":2,"name":"Fan Chen","email":"","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Fan","middleName":"","lastName":"Chen","suffix":""},{"id":626830611,"identity":"3e65c35d-1613-4a64-a930-ac6de6fed29a","order_by":3,"name":"Wenzhe Wang","email":"","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Wenzhe","middleName":"","lastName":"Wang","suffix":""},{"id":626830612,"identity":"b7c17c86-ab26-43c2-a961-b6ec3d00e69d","order_by":4,"name":"Chaoqun Yu","email":"","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Chaoqun","middleName":"","lastName":"Yu","suffix":""},{"id":626830613,"identity":"924d4e82-45a3-4771-80f3-de552f4714d5","order_by":5,"name":"Nanyu Pang","email":"","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Nanyu","middleName":"","lastName":"Pang","suffix":""},{"id":626830614,"identity":"8a734534-29b4-4831-8159-630694f26900","order_by":6,"name":"Feiyu Mu","email":"","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":false,"prefix":"","firstName":"Feiyu","middleName":"","lastName":"Mu","suffix":""},{"id":626830615,"identity":"4ab087c9-9cab-475f-ab07-34a3df27e8dc","order_by":7,"name":"Haining Zhang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABFElEQVRIiWNgGAWjYDACCSBmbGDgYWAGMhIq/svxMzMffEC8lgdnmI0l29mSDYjRAgaMD9uYEw3O85gJ4NMhP7v52cOvO+xkzNl5D79IbGNLMD7MYMbAUGMTjUsL45xj5sayZ5J5LJv50iwSzvHkmR1mSHvAcCwttwGHFmaJBDNpyTZmHoPDPGYGCWUSxUAtxw0YGw7j1MImkf4NqKUeqoXNIHFzM2ObBD4tPBI5ZpIf2w6DtBg/SGhLSNzAzMyGV4uERE6ZNGPbcbAtDAlnDhhLHGZjNkjA4xf5GenbJH+2VdsbnD9j/PFHxQE5/v7zHx98qLHBqQUcBDwwf8GFEvAoBwHGH1CtHwgoHAWjYBSMghEKADwQV2RRRh3eAAAAAElFTkSuQmCC","orcid":"","institution":"Affiliated Hospital of Qingdao University","correspondingAuthor":true,"prefix":"","firstName":"Haining","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2026-04-10 15:56:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9381432/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9381432/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107675893,"identity":"9db6e81b-fb68-49be-afbe-798a7ca5f91d","added_by":"auto","created_at":"2026-04-24 00:48:03","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":151783,"visible":true,"origin":"","legend":"\u003cp\u003eFlowchart of the patient selection process in the study\u003c/p\u003e\n\u003cp\u003eTKAs = total knee arthroplasties\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-9381432/v1/c14ec43ec8043b6681cf7d73.png"},{"id":107706959,"identity":"b79007db-e9a9-4f5e-a6b0-a61d4fd95c07","added_by":"auto","created_at":"2026-04-24 09:19:07","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":911017,"visible":true,"origin":"","legend":"\u003cp\u003eThe measurement of the coronal alignment parameters on standing full-limb anteroposterior radiographs\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003e The hip–knee–ankle angle (mHKA) was shown as a medial angle formed between the femoral mechanical axis and the tibial mechanical axis. \u003cstrong\u003eb\u003c/strong\u003e The lateral distal femoral angle (LDFA) was shown as a lateral angle formed between the femoral mechanical axis andthe distal articular surface of the femoral condyles. The medial proximal tibial angle (MPTA) was shown as a medial angle formed between the tibial mechanical axis and the proximal articular surface of the tibial platform.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-9381432/v1/7990b1c4f4c822d80112cd28.png"},{"id":107675895,"identity":"a5044657-4170-4269-a5c6-deed9ff608b4","added_by":"auto","created_at":"2026-04-24 00:48:03","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":751964,"visible":true,"origin":"","legend":"\u003cp\u003eThe measurement of the rotational alignment parameters on axial computed tomographic scan images\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea\u003c/strong\u003eThe femoral neck axis (A). \u003cstrong\u003eb\u003c/strong\u003e The clinical transepicondylar axis (B1) and the posterior condylar line (B2). \u003cstrong\u003ec\u003c/strong\u003e The proximal tibia axis (C). \u003cstrong\u003ed\u003c/strong\u003eThe distal tibia axis (D).\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-9381432/v1/ff0fde60d2a765e3809cc2ce.png"},{"id":107675896,"identity":"3de5b77e-1702-451f-84dc-a22f99f26bf1","added_by":"auto","created_at":"2026-04-24 00:48:03","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":241733,"visible":true,"origin":"","legend":"\u003cp\u003eCorrelation between coronal and rotational alignment parameters\u003c/p\u003e\n\u003cp\u003eFAA = femoral anteversion angle; CTA = condylar twisting angle; TTA = tibial torsion angle; mHKA = mechanical hip-knee-ankle angle; LDFA = lateral distal femoral angle; MPTA = medial proximal tibial angle\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-9381432/v1/e53d69d8db971c26627b4a86.png"},{"id":107709160,"identity":"d134d713-ac43-4e0b-93d6-91c17f54ba2d","added_by":"auto","created_at":"2026-04-24 09:34:51","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2328585,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9381432/v1/20b5ed5e-0a31-47ac-a478-dad29a0d72ef.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Limited ability of coronal alignment parameters to assess rotational alignment in patients with varus knee osteoarthritis: a cross-sectional study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eRotational alignment is a challenge for total knee arthroplasty (TKA). During the progression of knee osteoarthritis (KOA), torsional relationships between the hip and ankle relative to the knee may change [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Previous studies have demonstrated that rotational deformities of the femur and tibia can result in knee pain, patellar instability, and abnormal gait patterns [\u003cspan additionalcitationids=\"CR5 CR6 CR7\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Furthermore, rotational deformities of the lower extremity may contribute to component malrotation. Malrotation of femoral and tibial components often impairs tibiofemoral kinematics, thereby reducing functional scores and patient satisfaction [\u003cspan additionalcitationids=\"CR10 CR11\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Therefore, accurate assessment of rotational alignment parameters is essential for achieving optimal TKA outcomes.\u003c/p\u003e \u003cp\u003eRotation alignment parameters have traditionally been evaluated using computed tomography (CT) imaging. However, the absence of preoperative CT assessment in most TKA cases and the lack of accurate intraoperative measurement techniques render the identification of individuals with rotational abnormalities challenging. Coronal radiographs offer a simple, accurate, and cost-effective method for assessing the severity of varus and valgus deformities in patients with knee osteoarthritis. Previous studies have demonstrated significant correlations between rotational parameters, including the femoral anteversion angle (FAA), condylar twist angle (CTA), and tibial torsion angle (TTA), and changes in coronal alignment from varus to valgus [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. These findings provide a basis for preoperative identification of patients with abnormal rotational parameters and for intraoperative adjustment of component rotation, which is of considerable importance for improving surgical precision, optimizing implant positioning, reducing postoperative complications, and enhancing functional recovery and patient satisfaction.\u003c/p\u003e \u003cp\u003eThese rotational parameters differ between patients with varus and valgus knees [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, Asian patients with KOA predominantly present with varus deformity [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Given the distinct pathological mechanisms underlying varus and valgus knees in KOA, the relationship between rotational and coronal alignment parameters may not be applicable to patients with varus deformity. Patients with varying degrees of varus deformity may exhibit similar rotational parameters due to shared pathological processes, which could compromise the identification of individuals with abnormal lower limb rotation. We hypothesized that coronal alignment parameters would not reflect variations in rotational alignment among patients with varus KOA. The present study investigates whether rotational alignment parameters differ across patients with varying severities of varus deformity. Additionally, we examined whether coronal alignment parameters, including the mechanical hip\u0026ndash;knee\u0026ndash;ankle angle (mHKA), lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA), correlate with rotational alignment parameters, including FAA, CTA, and TTA, in patients with varus KOA.\u003c/p\u003e"},{"header":"Materials and methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy population\u003c/h2\u003e \u003cp\u003eWe conducted a retrospective, observational, and single-center study of 315 total knee arthroplasties (TKAs) in 290 patients (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Patients who underwent TKA between December 2023 and June 2025 were assessed for eligibility. The inclusion criteria were cases that presented with the end-stage of KOA, and had preoperative standing full-limb anteroposterior radiographs along with axial CT scans. The exclusion criteria were preoperative valgus alignment of the lower extremity, rheumatoid arthritis, flexion contracture\u0026thinsp;\u0026gt;\u0026thinsp;10\u0026deg;, and a previous history of lower extremity fracture or surgery. All cases were divided into two groups based on the degree of preoperative varus deformity. The cases with 0\u0026deg; \u0026le; varus\u0026thinsp;\u0026lt;\u0026thinsp;10\u0026deg; were assigned to the mild varus group, and the cases with 10\u0026deg; \u0026le; varus were assigned to the severe varus group. The demographic data and preoperative angles of these subjects are summarised in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic characteristics and lower limb alignment parameters of patients stratified by varus severity\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eParameters\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMild varus group (n\u0026thinsp;=\u0026thinsp;141)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSevere varus group (n\u0026thinsp;=\u0026thinsp;174)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u0026deg; \u0026le; varus\u0026thinsp;\u0026lt;\u0026thinsp;10\u0026deg;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e10\u0026deg; \u0026le; varus\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e67.6\u0026thinsp;\u0026plusmn;\u0026thinsp;5.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e67.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.703\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex (men : women)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e33 : 108\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e41 : 133\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.974\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eHeight (cm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e162.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e162.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.861\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWeight (kg)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e72.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e73.9\u0026thinsp;\u0026plusmn;\u0026thinsp;11.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.176\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e27.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.0\u0026thinsp;\u0026plusmn;\u0026thinsp;3.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.280\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emHKA (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e173.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e166.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLDFA (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e87.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e90.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMPTA (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e85.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e83.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFAA (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15.1\u0026thinsp;\u0026plusmn;\u0026thinsp;8.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.8\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.081\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTA (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.8\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.493\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTTA (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25.0\u0026thinsp;\u0026plusmn;\u0026thinsp;7.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25.4\u0026thinsp;\u0026plusmn;\u0026thinsp;7.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.593\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eAbbreviation: BMI\u0026thinsp;=\u0026thinsp;body mass index; mHKA\u0026thinsp;=\u0026thinsp;mechanical hip-knee-ankle angle; LDFA\u0026thinsp;=\u0026thinsp;lateral distal femoral angle; MPTA\u0026thinsp;=\u0026thinsp;medial proximal tibial angle; FAA\u0026thinsp;=\u0026thinsp;femoral anteversion angle; CTA\u0026thinsp;=\u0026thinsp;condylar twisting angle; TTA\u0026thinsp;=\u0026thinsp;tibial torsion angle\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eImaging techniques\u003c/h3\u003e\n\u003cp\u003eAxial CT (SOMATOM\u0026reg; Perspective, Siemens Healthcare GmbH, Erlangen, Germany) was used to acquire simultaneous axial images of the hip, knee, and ankle joints. The lower extremities of patients were fixed with a cylindrical metal rod in a state of neutral rotation in a supine position to obtain the CT scan[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Multislice CT images (130 keV, 170 mA) of the whole lower extremity with multiplanar reconstruction (slice thickness of 1.00 mm; reconstruction interval of 1.00 mm) were also obtained.\u003c/p\u003e \u003cp\u003eStanding full-limb anteroposterior radiographs were obtained using an X-ray machine (Philips SRO 33100, Philips, Eindhoven, The Netherlands) at a source-to-image distance of 180 cm. To ensure the authenticity of the radiographs, all the imaging procedures were performed in strict accordance with the following standardized protocol. For standing full-limb anteroposterior radiographs, patients were positioned upright with the back against the detector, knees fully extended, feet shoulder-width apart, and internally rotated approximately 15\u0026deg;, ensuring one-third overlap of the fibular head with the tibia and anterior orientation of the patellae.\u003c/p\u003e\n\u003ch3\u003eMeasurements\u003c/h3\u003e\n\u003cp\u003eAll radiographs were digitally obtained by the Centricity\u0026trade; universal viewer zero footprint. The coronal parameters, including mHKA, LDFA, and MPTA, were shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. All the coronal parameters were measured in standing full-limb anteroposterior radiographs. The mHKA was defined as a medial angle formed between femoral mechanical axis and tibial mechanical axis. The LDFA was defined as a lateral angle formed between femoral mechanical axis and the distal articular surface of the femoral condyles. The MPTA was defined as a medial angle formed between tibial mechanical axis and the proximal articular surface of the tibial platform. The varus deformity angle was calculated as 180\u0026deg; minus the mHKA.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe rotational parameters, including femoral anteversion angle (FAA), condylar twisting angle CTA, and tibial torsion angle (TTA), were shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. All the coronal parameters were measured on axial CT images. The FAA was measured by the medial angle formed between the femoral neck axis and the posterior condylar line (PCL) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Femoral anteversion was defined as a positive value. The CTA was measured by the medial angle formed between the PCL and the clinical transepicondylar axis (cTEA) [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. The relative internal rotation of the PCL with respect to the cTEA was defined as a positive value. The TTA was measured by the lateral angle formed between the proximal and the distal tibia axis [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Relative internal rotation of the proximal tibia with respect to the distal tibia was defined as a positive value.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eAll statistical analyses were conducted using RStudio software (version 4.4.1), with p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 considered statistically significant. The Shapiro-Wilk test was conducted for continuous variables to evaluate the normality of the data. For two independent groups, a t-test was used to compare means when the data were normally distributed, whereas the Wilcoxon rank-sum test was applied when the data did not follow a normal distribution. The chi-square test was used to compare categorical variables between two independent groups. Spearman correlation analysis was utilized to evaluate the statistical significance of the association between the coronal parameters and the rotational parameters of the lower extremity in different varus groups. Intraclass correlation coefficients (ICCs) were employed to assess the intra-observer and inter-observer reliabilities of the radiographic measurement techniques. Two independent observers repeated the measurements twice, separated by a two-week interval. The ICCs for both intra-observer and inter-observer evaluations demonstrated excellent consistency (\u0026gt;\u0026thinsp;0.8).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 315 TKAs were enrolled and eligible for the study. According to the varus deformity angle, 141 TKAs and 174 TKAs were classified into the mild varus and severe varus groups, respectively. The mean age of the total varus group was 67.5\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7 years, the mean height was 162.1\u0026thinsp;\u0026plusmn;\u0026thinsp;7.3, and the mean weight was 73.1\u0026thinsp;\u0026plusmn;\u0026thinsp;11.3. The cases included 241 (76.5%) women and 74 (23.5%) men. There was a significant difference (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) in all the coronal parameters between the mild varus and severe varus groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The mean mHKA was 173.4\u0026deg; \u0026plusmn; 2.4\u0026deg; in the mild varus group, and 166.1\u0026deg; \u0026plusmn; 3.0\u0026deg; in the severe varus group. The mean LDFA was 87.9\u0026deg; \u0026plusmn; 2.2\u0026deg; in the mild varus group, and 90.1\u0026deg; \u0026plusmn; 2.3\u0026deg; in the severe varus group. The mean MPTA was 85.7\u0026deg; \u0026plusmn; 2.0\u0026deg; in the mild varus group, and 83.2\u0026deg; \u0026plusmn; 2.3\u0026deg; in the severe varus group. However, no significant differences (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) in any rotational parameters were observed between the mild varus and severe varus groups (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The mean FAA was 15.1\u0026deg; \u0026plusmn; 8.8\u0026deg; in the mild varus group, and 16.8\u0026deg; \u0026plusmn; 8.9\u0026deg; in the severe varus group. The mean CTA was 5.8\u0026deg; \u0026plusmn; 2.2\u0026deg; in the mild varus group, and 5.6\u0026deg; \u0026plusmn; 2.1\u0026deg; in the severe varus group. The mean TTA was 25.0\u0026deg; \u0026plusmn; 7.7\u0026deg; in the mild varus group, and 25.4\u0026deg; \u0026plusmn; 7.4\u0026deg; in the severe varus group.\u003c/p\u003e \u003cp\u003eCorrelation analysis was performed to evaluate the relationships between the coronal parameters and the rotational parameters. Neither FAA nor CTA was significantly associated with mHKA or LDFA in any of the varus groups. In the total varus group, only TTA was significantly associated with MPTA (r\u0026thinsp;=\u0026thinsp;0.118, p\u0026thinsp;=\u0026thinsp;0.036) (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). In the mild varus group, only TTA was significantly associated with MPTA (r\u0026thinsp;=\u0026thinsp;0.200, p\u0026thinsp;=\u0026thinsp;0.020) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). In the severe varus group, only TTA was significantly associated with mHKA (r\u0026thinsp;=\u0026thinsp;0.239, p\u0026thinsp;=\u0026thinsp;0.001) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The scatter plots and regression lines for the relationship between coronal and rotational alignment parameters are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorrelation analysis between coronal alignment parameters and rotational alignment parameters across the entire varus cohort\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eRotational parameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCoronal parameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCorrelation coefficient\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emHKA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.094\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.095\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emHKA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.053\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.348\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emHKA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.804\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.014\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.797\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.090\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMPTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.118\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.036\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"4\"\u003eAbbreviation: FAA\u0026thinsp;=\u0026thinsp;femoral anteversion angle; CTA\u0026thinsp;=\u0026thinsp;condylar twisting angle; TTA\u0026thinsp;=\u0026thinsp;tibial torsion angle; mHKA\u0026thinsp;=\u0026thinsp;mechanical hip-knee-ankle angle; LDFA\u0026thinsp;=\u0026thinsp;lateral distal femoral angle; MPTA\u0026thinsp;=\u0026thinsp;medial proximal tibial angle\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSubgroup correlation analysis between coronal and rotational alignment parameters stratified by varus severity\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eRotational parameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eCoronal parameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c4\" namest=\"c3\"\u003e \u003cp\u003eMild varus group (0\u0026deg; \u0026le; varus\u0026thinsp;\u0026lt;\u0026thinsp;10\u0026deg;, n\u0026thinsp;=\u0026thinsp;141)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c6\" namest=\"c5\"\u003e \u003cp\u003eSevere varus group (10\u0026deg; \u0026le; varus, n\u0026thinsp;=\u0026thinsp;174)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCorrelation coefficient\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eCorrelation coefficient\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emHKA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.116\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.171\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.128\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.091\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emHKA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.095\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.265\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.133\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.080\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003emHKA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.078\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.356\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.239\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.818\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.029\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.705\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e\u0026minus;0.058\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.493\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e\u0026minus;0.134\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.079\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMPTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.200\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.020\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0.125\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e0.100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003eAbbreviation: FAA\u0026thinsp;=\u0026thinsp;femoral anteversion angle; CTA\u0026thinsp;=\u0026thinsp;condylar twisting angle; TTA\u0026thinsp;=\u0026thinsp;tibial torsion angle; mHKA\u0026thinsp;=\u0026thinsp;mechanical hip-knee-ankle angle; LDFA\u0026thinsp;=\u0026thinsp;lateral distal femoral angle; MPTA\u0026thinsp;=\u0026thinsp;medial proximal tibial angle\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThis study investigated the relationship between coronal alignment parameters and rotational alignment parameters in patients with varus knee osteoarthritis. Among the 315 TKAs included in the present study, the varus knee deformity measured a mean of 6.6\u0026deg; in the mild varus group and 13.9\u0026deg; in severe cases (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). However, there were no statistically significant differences in the rotational angles (FAA, CTA, and TTA) between patients with mild varus deformity and those with severe varus deformity. Furthermore, femoral rotational alignment parameters (FAA and CTA) had no significant correlations with mHKA and LDFA. Notably, we found significant correlations between both mHKA and MPTA and the tibial rotational alignment parameter (TTA).\u003c/p\u003e \u003cp\u003eThere are differences in rotational alignment between patients with varus and valgus deformities. Chang et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] reported that the mean rotational alignment parameters in patients with valgus deformities (FAA\u0026thinsp;=\u0026thinsp;16.7\u0026deg;, CTA\u0026thinsp;=\u0026thinsp;10.2\u0026deg;, TTA\u0026thinsp;=\u0026thinsp;32.6\u0026deg;) were higher than those in patients with varus deformities (FAA\u0026thinsp;=\u0026thinsp;10.9\u0026deg;, CTA\u0026thinsp;=\u0026thinsp;6.6\u0026deg;, TTA\u0026thinsp;=\u0026thinsp;22.6\u0026deg;). Similarly, Le\u0026oacute;n-Mu\u0026ntilde;oz et al. [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] reported that the mean rotational alignment parameters in valgus deformities (FAA\u0026thinsp;=\u0026thinsp;12.1\u0026deg;; CTA\u0026thinsp;=\u0026thinsp;6.4\u0026deg;; TTA\u0026thinsp;=\u0026thinsp;24.6\u0026deg;) were higher than those in patients with varus deformities (FAA\u0026thinsp;=\u0026thinsp;10.8\u0026deg;; CTA\u0026thinsp;=\u0026thinsp;5.4\u0026deg;; TTA\u0026thinsp;=\u0026thinsp;18.6\u0026deg;). Adjusting the prosthetic rotational alignment based on the preoperative deformity type can result in satisfactory clinical outcomes in TKA [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. However, there is no consensus on whether prosthetic rotation should be adjusted based on the severity of varus deformity. Yoon et al. [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] suggest that prosthetic rotation should be adjusted to the degree of varus deformity in knee varus patients. However, previous studies demonstrated no significant differences in postoperative functional scores or complication rates between mild and severe varus deformity patients [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Furthermore, Oh et al. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] confirmed that the long-term survival in TKAs had no significant difference in different degrees of preoperative varus deformity. Our study indicated that no statistical difference was found between the mild and severe varus groups in terms of rotational profiles. Consequently, we do not recommend using the severity of varus deformity to guide intraoperative prosthetic rotational alignment.\u003c/p\u003e \u003cp\u003eMalrotation of femoral components remains a major cause of early TKA revision [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. It has been shown that axial malrotation of femoral components can lead to postoperative pain, patellofemoral maltracking or instability, accelerated wear, or implant loosening [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Luyckx et al. [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] found that for each 1\u0026deg; increase in coronal alignment from varus to valgus, the posterior condylar angle increased by 0.1\u0026deg;. However, we did not find a significant correlation between CTA and mHKA or LDFA in varus patients. Although our study shows no significant correlation between FAA and mHKA or LDFA, decreased femoral anteversion increases hip external rotation and toe-out gait [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. Although the FAA does not show a significant correlation with mHKA and LDFA, decreased femoral anteversion increases hip external rotation and toe-out gait. Additionally, the femoral distal shows a considerable individual variability in the rotational alignment [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. To improve femoral prosthetic rotation accuracy, surgeons should consider anatomical variations and perform additional measurements preoperatively and intraoperatively.\u003c/p\u003e \u003cp\u003eExcessive internal rotation of the tibial component in TKA is a widely recognized risk factor for postoperative pain and inferior functional outcomes. Nicoll and Rowley [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] reported that more than half of the 740 consecutive TKA cases who experienced postoperative pain had excessive internal rotation of the tibial component. Similarly, Barrack et al. [\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] reported that patients who presented with anterior knee pain exhibited an average internal rotation of the tibial component of 6.2\u0026deg;, compared with only 0.4\u0026deg; in the asymptomatic control group. Our study found that in all varus patients, the internal rotation of the proximal tibia relative to the distal tibia was significantly associated with a decrease in MPTA. However, in patients with severe varus deformity, the internal rotation of the proximal tibia relative to the distal tibia was significantly associated with a decrease in mHKA, but not with a decrease in MPTA. Therefore, in patients with varus knee osteoarthritis, surgeons need to carefully assess tibial rotation and avoid excessive internal rotation of the tibial component.\u003c/p\u003e \u003cp\u003eThis study had several limitations. First, our study included Asian patients with females predominating. A previous study showed that anatomic torsional parameters vary across races [\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e]. Our results should be interpreted with caution when extrapolated to populations with different racial or sex distributions. Second, this study evaluated lower-limb rotational profiles using CT, which provides a static rather than a dynamic assessment. As a result, soft-tissue conditions that may influence dynamic limb alignment were not captured. Third, articular cartilage erosion can affect rotational parameters in KOA patients undergoing TKA. While cartilage status was not explicitly analyzed, all participants were in the end-stage of KOA requiring TKA, indicating that the risk of bias was likely minimal. Finally, this study only focused on patients with varus osteoarthritis. The coronal and axial alignment relationships in patients with varying degrees of valgus deformity require further investigation in future studies. Finally, this study lacked a clinical outcome.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe assessment of lower limb coronal alignment has limited ability to evaluate rotational alignment in patients with end-stage varus knee osteoarthritis. Therefore, surgeons should carefully evaluate rotational alignment both preoperatively and intraoperatively to identify patients with rotational abnormalities.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eKOA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eknee osteoarthritis\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003emHKA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003emechanical hip\u0026ndash;knee\u0026ndash;ankle angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLDFA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003elateral distal femoral angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMPTA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003emedial proximal tibial angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTKA\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\"\u003eCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ecomputed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFAA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003efemoral anteversion angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCTA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003econdylar twist angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTTA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003etibial torsion angle\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eTKAs\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003etotal knee arthroplasties\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePCL\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eposterior condylar line\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ecTEA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eclinical transepicondylar axis\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eICCs\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eintraclass correlation coefficients\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of the Affiliated Hospital of Qingdao University (Project ID: QYFY WZLL 30614). Informed consent was obtained from all participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003ch3\u003eConflict of interest\u003c/h3\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eH.W. and Z.Z. wrote the paper and edited the manuscript. N.P. and F.M. collected the data. F.C. and W.W. measured the imaging parameters. C.Y. performed all the statistical analysis. H.Z. designed the whole study and revised the paper. All authors have read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank all their colleagues for their kind help and all patients for their cooperation with our work.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eYagi T, Sasaki T. Tibial torsion in patients with medial-type osteoarthritic knee. Clin Orthop Relat Res 1986(213):177\u0026ndash;82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEckhoff DG, Kramer RC, Alongi CA, VanGerven DP. Femoral anteversion and arthritis of the knee. 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Knee Surg Sports Traumatol Arthrosc. 2010;18(7):863\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00167-009-0990-y\u003c/span\u003e\u003cspan address=\"10.1007/s00167-009-0990-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eEisenhuth SA, Saleh KJ, Cui Q, Clark CR, Brown TE. Patellofemoral instability after total knee arthroplasty. Clin Orthop Relat Res. 2006;446:149\u0026ndash;60. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/01.blo.0000214415.83593.db\u003c/span\u003e\u003cspan address=\"10.1097/01.blo.0000214415.83593.db\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLuyckx T, Zambianchi F, Catani F, Bellemans J, Victor J. 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Internal rotational error of the tibial component is a major cause of pain after total knee replacement. J Bone Joint Surg Br. 2010;92(9):1238\u0026ndash;44. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1302/0301-620x.92b9.23516\u003c/span\u003e\u003cspan address=\"10.1302/0301-620x.92b9.23516\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBarrack RL, Schrader T, Bertot AJ, Wolfe MW, Myers L. Component rotation and anterior knee pain after total knee arthroplasty. Clin Orthop Relat Res 2001(392):46\u0026ndash;55. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/00003086-200111000-00006\u003c/span\u003e\u003cspan address=\"10.1097/00003086-200111000-00006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMathon P, Micicoi G, Seil R, et al. Healthy middle-aged Asian and Caucasian populations present with large intra- and inter-individual variations of lower limb torsion. Knee Surg Sports Traumatol Arthrosc. 2021;29(4):1083\u0026ndash;9. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00167-020-06096-0\u003c/span\u003e\u003cspan address=\"10.1007/s00167-020-06096-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Total knee arthroplasty, Varus deformity, Rotational alignment, Coronal alignment, Osteoarthritis","lastPublishedDoi":"10.21203/rs.3.rs-9381432/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9381432/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eThis study aimed to investigate whether rotational alignment parameters vary across different severities of varus deformity and to examine the correlation between coronal and rotational alignment parameters in end-stage varus knee osteoarthritis (KOA).\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eWe performed a retrospective study on 315 lower extremities with end-stage KOA. The lower extremities were categorized into the mild varus group (n\u0026thinsp;=\u0026thinsp;141) and the severe varus (n\u0026thinsp;=\u0026thinsp;174) group according to mechanical hip-knee-ankle angle (mHKA). Coronal alignment parameters were measured on standing full-limb radiographs, including the mHKA, lateral distal femoral angle (LDFA), and medial proximal tibial angle (MPTA). Rotational alignment parameters were measured on computed tomography (CT), including the femoral anteversion angle (FAA), condylar twist angle (CTA), and tibial torsion angle (TTA).\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eWe found no significant differences in any lower-limb rotational parameters between the mild varus and severe varus groups. Correlation analysis revealed that only TTA was significantly correlated with coronal alignment parameters, which was associated with MPTA in the mild varus group (r\u0026thinsp;=\u0026thinsp;0.200, p\u0026thinsp;=\u0026thinsp;0.020), mHKA in the severe varus group (r\u0026thinsp;=\u0026thinsp;0.239, p\u0026thinsp;=\u0026thinsp;0.001), and mHKA in the entire varus cohort (r\u0026thinsp;=\u0026thinsp;0.118, p\u0026thinsp;=\u0026thinsp;0.036).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe assessment of lower limb coronal alignment has limited ability to evaluate rotational alignment in patients with end-stage varus knee osteoarthritis. Therefore, surgeons should carefully evaluate rotational alignment both preoperatively and intraoperatively to identify patients with rotational abnormalities.\u003c/p\u003e","manuscriptTitle":"Limited ability of coronal alignment parameters to assess rotational alignment in patients with varus knee osteoarthritis: a cross-sectional study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-24 00:47:55","doi":"10.21203/rs.3.rs-9381432/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-05-13T06:50:27+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-10T05:17:55+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-05T19:12:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"335385714055689975578315052236619349830","date":"2026-04-19T19:12:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"298861665188301228462232646070383779178","date":"2026-04-19T04:34:05+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"86401332156232927252997342035067418607","date":"2026-04-16T13:39:56+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-04-15T23:19:58+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-04-14T10:57:23+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-04-13T11:23:40+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-04-13T11:22:42+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2026-04-10T15:38:34+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4e3327f4-2944-443b-8a14-b5516ad70ec0","owner":[],"postedDate":"April 24th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Revision requested","date":"2026-05-13T06:50:27+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-10T05:17:55+00:00","index":43,"fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-05-05T19:12:04+00:00","index":41,"fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"in-revision","subjectAreas":[],"tags":[],"updatedAt":"2026-05-13T06:56:17+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-24 00:47:55","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9381432","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9381432","identity":"rs-9381432","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}