Preservation of joint line obliquity is not a critical factor for improving patient satisfaction

Preservation of joint line obliquity is not a critical factor for improving patient satisfaction | 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 Preservation of joint line obliquity is not a critical factor for improving patient satisfaction Sang Jun Song, Young Kook Kim, Cheol Hee Park This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7104332/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose: This study has aimed to evaluate the clinical outcomes in paired bilateral posterior stabilized (PS) TKAs with significantly different degrees of joint line obliquity (JLO) change. Methods: A retrospective review was conducted on 128 patients who underwent paired bilateral PS TKAs, with greater and smaller JLO changes (G-ΔJLO and S-ΔJLO knees; difference between greater and smaller JLO change >3°). The mean follow-up period was 3.9 years (minimum 2 years). Radiographic changes in JLO were measured according to the Coronal Plane Alignment of the Knee (CPAK) classification. Maintenance of the CPAK type and JLO direction (apex distal, neutral, and apex proximal) was investigated. Clinically, the preferred TKA out of greater and smaller JLO changes was investigated. The Hospital for Special Surgery and Western Ontario and McMaster Universities Osteoarthritis Index were evaluated. Results: The average JLO change was 10.5° in the G-ΔJLO knees and 5.5° in the S-ΔJLO knees (p < 0.001). The CPAK type and JLO direction was better maintained in the S-ΔJLO knees (p < 0.001, repsectively). Regarding preference, 40 patients (31.2%) were satisfied with bilateral TKAs without a specific preference, while 44 patients (34.3%) preferred TKAs of the G-ΔJLO knee and 44 patients (34.3%) preferred the S-ΔJLO knee (p = 1.000). No significant differences were found in the patient reported outcomes between the G- and S-ΔJLO knees. Conclusion: The degree of JLO preservation did not significantly affect clinical outcomes of PS TKAs. JLO preservation will not be a critical factor in improving patient satisfaction for PS TKA. Level of evidence: III Knee Total knee arthroplasty Posterior stabilized Joint line obliquity Satisfaction Figures Figure 1 Introduction Preservation of joint line obliquity (JLO) has recently garnered attention as a potential factor improving patient satisfaction after total knee arthroplasty (TKA) [ 1 – 4 ]. Previous studies have suggested that JLO preservation contributes to better restoration of native knee kinematics and enhances clinical outcomes [ 1 – 4 ]. However, these studies primarily investigated cruciate-retaining (CR) TKAs, which preserves the posterior cruciate ligament (PCL), an important structure for replicating native knee kinematics. In posterior-stabilized (PS) TKA, which involves removal of PCL and thereby limits the ability to replicate natural knee kinematics, the preservation of the JLO may have limited clinical impact [ 5 – 7 ]. Multiple factors influence patient satisfaction after TKA, among which preoperative expectations, psychological factors, pain sensitivity, and lifestyle inevitably vary from person to person [ 8 – 10 ]. Most studies analyzing the relationship between JLO preservation and clinical outcomes have not rigorously controlled for these factors [ 2 , 5 , 11 – 13 ]. Given this limitation, a more reliable assessment of the effects of JLO preservation can be achieved by analyzing patient preference in TKAs performed on paired knees using the same prosthesis but with significantly different degrees of JLO preservation. This study aimed to evaluate the clinical outcomes, including patient preferences, in paired bilateral PS TKAs performed with the same prosthesis but with significantly different degrees of JLO change. Our hypothesis was that the degree of JLO preservation would not significantly influence the clinical outcomes in PS TKAs. Materials and Methods Patients This retrospective study included patients who underwent 1-week staged bilateral primary TKA using either Attune® (Depuy Synthes, Warsaw, IN, USA) or Persona® (Zimmer, Warsaw, IN, USA) PS prosthesis at our hospital between January 2018 and December 2022. All surgeries were performed by a senior surgeon who had had surgical experience with over 5,000 TKAs before the study period. Patients were included if the met the following criteria: (1) bilateral Kellgren–Lawrence grade 4 degenerative osteoarthritis preoperatively; (2) similar preoperative arithmetic hip-knee-ankle angle (aHKA) and JLO between paired knees, defined as absolute differences ≤ 2° and ≤ 3°, respectively [ 14 ]; (3) paired TKAs with significantly different postoperative JLO changes (difference > 3° between greater and smaller JLO change) [ 3 ]; (4) a minimum follow-up period of 2 years; and (5) availability of clinical and radiographic data before and after surgery. Exclusion criteria included: (1) inflammatory arthritis; (2) a history of femoral or tibial fracture, knee dislocation, or ligament injury; (3) a history of distal femoral or high tibial osteotomy; and (4) presence of femoral and tibial diaphyseal deformity. Based on these criteria, 128 patients were included in this study. The patient demographics are presented in Table 1 . No significant differences were observed regarding preoperative clinical and radiographic knee conditions between paired TKAs with greater JLO change (Greater-ΔJLO knees) and smaller JLO change (Smaller-ΔJLO knees) (Tables 2 and 3 ). This study was approved by the Institutional Review Board of our institution. Informed consent was obtained from all of the patients before commencing the review. Table 1 Patient demographics Operating period Jan 2018– Dec 2022 Number of patients 128 Age* 71.2 ± 5.0 Female/Male 120 / 8 Body mass index (kg/m 2 )* 26.1 ± 3.3 Type of Prostheses (Attune®/ Persona®) 68 / 60 Follow-up period (year) 3.9 ± 1.5 * Continuous variables are presented as mean ± standard deviation. Table 2 Radiographic results G-ΔJLO S-ΔJLO p-value mLDFA (°) Preoperative 89.4 ± 2.6 89.7 ± 2.2 0.148 Postoperative 92.8 ± 1.7 90.8 ± 1.5 < 0.001 mMPTA (°) Preoperative 84.0 ± 2.5 84.0 ± 2.4 0.881 Postoperative 91.1 ± 1.4 88.4 ± 1.5 < 0.001 aHKA (°) Preoperative -5.4 ± 3.2 -5.6 ± 3.5 0.418 Postoperative -1.8 ± 1.8 -2.5 ± 2.3 0.002 Change 3.6 ± 3.3 3.1 ± 3.3 0.261 JLO (°) Preoperative 173.4 ± 3.9 173.7 ± 3.1 0.130 Postoperative 183.9 ± 2.5 179.2 ± 2.1 < 0.001 Change 10.5 ± 3.3 5.5 ± 3.3 < 0.001 PTS Preoperative 10.7 ± 3.7 10.9 ± 3.3 0.199 Postoperative 3.3 ± 2.3 3.4 ± 2.5 0.471 Change 7.4 ± 4.4 7.5 ± 3.9 0.789 Data are presented as mean ± standard deviation. G-ΔJLO, TKAs with a greater change in the joint line obliquity; S-ΔJLO, TKAs with a smaller change in the joint line obliquity; mLDFA, mechanical lateral distal femoral angle; mMPTA, mechanical medial proximal tibial angle; aHKA, arithmetic hip-knee-ankle angle; JLO, joint line obliquity; PTS, posterior tibial slope. Table 3 Clinical results G-ΔJLO S-ΔJLO p -value HSS Preoperative 37.1 ± 6.4 37.5 ± 7.6 0.249 Last follow-up 93.2 ± 5.7 92.9 ± 5.0 0.540 WOMAC Preoperative 68.2 ± 3.0 67.8 ± 4.0 0.155 Last follow-up 9.8 ± 10.0 9.0 ± 8.8 0.307 Range of motion (°) Preoperative 116.8 ± 17.2 118.3 ± 20.7 0.291 Last follow-up 130.0 ± 15.1 128.8 ± 15.4 0.116 Data are presented as mean ± standard deviation G-ΔJLO, TKAs with a greater change in the joint line obliquity; S-ΔJLO, TKAs with a smaller change in the joint line obliquity; HSS, Hospital for Special Surgery; WOMAC, the Western Ontario and McMaster Universities osteoarthritis index Surgical techniques and rehabilitation All TKAs were performed using a tourniquet control. A medial parapatellar approach was used with a midline skin incision. An intramedullary guide was used for distal femoral resection. The distal femoral cut was performed at valgus angles of 4°, 5°, and 6°, using the intramedullary rod as a reference, corresponding to preoperative long-leg radiographic measurements of the angle between the femoral anatomical and mechanical axes of 7°, respectively. The transepicondylar axis was used for determining the femoral component rotation. An extramedullary guide was used for tibial resection, with the initial cutting plane positioned perpendicular to the mechanical tibial axis. The posterior tibial slope (PTS) was set at 3° in the sagittal plane, guided by a reference line connecting the fibular head and lateral malleolus. Tibial component rotation was determined using a reference line connecting the medial third of the tibial tubercle to the insertion point of the PCL. Following resection, trial implants were inserted. Mediolateral and flexion-extension balancing was achieved through bony adjustment prior to any soft tissue release. For mediolateral balancing, modification of the tibial cutting plane was prioritized. The coronal alignment of the cutting plane was adjusted within the range of varus 3° to valgus 3°. Flexion-extension gap balancing was achieved by modifying the tibial slope within the range of 0° to 6°[ 3 ]. If imbalance persisted despite adjustments being made to the bony cutting plane, selective release of the contracted soft tissue was performed. The appropriate thickness of the polyethylene insert was determined by considering stability and kinematics with proper ligament tension and physiological knee motion without hyperextension, flexion contracture, or lift-off of the trial insert. Patellar resurfacing was performed. All components were implanted on cleaned and dried cut surfaces using a full cementation technique. Isometric exercises using the extensor and flexor muscles were initiated shortly after the operation. The drain was removed on the first postoperative day, followed by initiation of active and assisted range of motion (ROM) exercises. Weight-bearing ambulation was also initiated on the first operative day, as tolerated by the patients. Radiographic evaluation The radiographic parameters were measured preoperatively and at the final follow-up visit. Preoperative and postoperative long-leg standing anteroposterior radiograph and lateral knee radiograph were obtained under weight-bearing conditions. The mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), aHKA, and JLO were measured on long-leg standing anteroposterior radiographs in accordance with the Coronal Plane Alignment of the Knee (CPAK) classification system [ 14 ]. mLDFA was defined as the lateral angle between the femoral mechanical axis and the tangent line of the most distal points of the femoral condyles in the native knee or implant. mMPTA was defined as the medial angle between the tibial mechanical axis and the tangent line of the native proximal tibial plateau or the tibial baseplate. aHKA was defined as the value obtained by subtracting mLDFA from mMPTA, whereas JLO was defined as the sum of mMPTA and mLDFA. PTS was measured using lateral knee radiographs [ 15 ]. Preoperative PTS was defined as the angle between the perpendicular line of the tibial intramedullary canal axis and the line connecting the anterior and posterior borders of the medial tibial plateau. For the measurement of the postoperative PTS, the tibial cutting surface was used. Radiographic quality was ensured by standardizing knee positioning and maintaining a consistent distance between the X-ray beam and cassette. All images were digitally transferred to a Picture Archiving and Communication System (PACS). Angular measurements were performed using PACS software, with a minimum detectable angular difference of 0.1°. In order to minimize any observational bias, two independent investigators performed all radiographic measurements. The interobserver reliabilities of all measurements were assessed using the intraclass correlation coefficient, and all values were greater than 0.8. Therefore, the average values obtained by the two investigators were used for analysis. Clinical evaluation The clinical outcomes were evaluated preoperatively and at the final follow-up visit. Patient preference between paired TKAs with greater and smaller JLO changes was investigated. The Hospital for Special Surgery score (HSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and ROM were evaluated. The ROM was measured using a long-armed goniometer. Complications Any complications were investigated according to the standardized list and definitions of complications provided by the Knee Society [ 16 ]. Statistical analysis The pre- and postoperative radiographic variables and clinical scores were compared between G- and S-ΔJLO knees using paired t-tests. The proportion of CPAK type and JLO direction (apex distal, neutral, and apex proximal) were compared between the G- and S-ΔJLO knees using Wilcoxon signed-rank test. The maintenance rates of CPAK type and JLO direction, as well as the preference rates, were compared using the McNemar test. All statistical analyses were performed using SPSS version 25.0 (Chicago, IL, USA). A p-value < 0.05 was considered statistically significant. Power analysis was performed to determine the minimum sample size required for sufficient statistical power in evaluating patient preference. This analysis was based on a hypothesis of non-inferiority between G- and S-ΔJLO knees, with a clinically acceptable difference in preference rate set at 20% [ 17 ]. The alpha level was set at 0.05, and the desired power was 80%. The performed power analysis indicated that > 70 patients were required for each group to ensure sufficient statistical power. Results Radiographically, no significant differences were observed in preoperative variables between the G- and S-ΔJLO knees (Table 2 ). Postoperatively, the femoral component showed more varus alignment in the G-ΔJLO knees, whereas the tibial component showed more varus alignment in the S-ΔJLO knees (Table 2 ). The average postoperative aHKA exhibited a more varus alignment in the S-ΔJLO knees; however, the mean change in aHKA between the two groups was not significantly different (Table 2 ). The average postoperative JLO displayed a more apex proximal obliquity in the G-ΔJLO knees (Table 2 ). The average JLO changes were 10.5° in the G-ΔJLO knees and 5.5° in the S-ΔJLO knees (p < 0.001). The preoperative and postoperative PTS and changes in PTS were not significantly different (Table 2 ). The postoperative proportions of CPAK type and JLO direction after surgery differed significantly (p < 0.001 for both) between the G- and S-ΔJLO knees, although the preoperative portions were not significantly different (p = 0.184 and 0.102, respectively) (Fig. 1 ). Maintenance of the original CPAK type was observed in 0 case in the G-ΔJLO knees and in 20 cases (15.6%) in the S-ΔJLO knees (p < 0.001). The direction of JLO was maintained in 0 case in the G-ΔJLO knees and in 37 cases (28.9%) in the S-ΔJLO knees (p < 0.001). Clinically, regarding preference, 40 patients (31.2%) were satisfied with bilateral TKAs without a specific preference, while 44 patients (34.3%) preferred TKAs of the G-ΔJLO knee and 44 patients (34.3%) preferred the S-ΔJLO knee; no significant difference was observed in the preference rates between the groups (p = 1.000). Additionally, no significant differences were found in the HSS, WOMAC, and ROM between the G- and S-ΔJLO knees at the last follow-up (Table 3 ). No complications were reported in either the G- or S-ΔJLO knees during the follow-up period. Discussion The most important finding of the present study was that clinical outcomes were comparable between paired bilateral PS TKAs with greater and smaller JLO changes at an average 3.9 years of follow-up. The degree of JLO preservation did not affect patient preference for PS TKAs. Previous studies involving CR TKAs have shown that JLO preservation is a crucial factor in optimizing clinical outcomes and improving patient satisfaction. Winnock de Grave et al. [ 4 ] reported that JLO preservation resulted in gait pattern similar to those of healthy native knees without increasing knee adduction moments after CR TKA. Clark et al. [ 2 ] reported that robot-assisted CR TKAs with better JLO preservation achieved higher Forgotten Joint Score-12 scores and greater ROM than those with less JLO preservation. However, other studies have challenged the advantages of JLO preservation in TKA designs that sacrifice the PCL. Recent gait analyses have shown that restoring the pre-arthritic joint line does not necessarily replicate native knee kinematics in TKA using a medially stabilized design with PCL sacrifice [ 6 ]. Rodriguez et al [ 5 ]. analyzed 23 pairs of bilateral paired TKAs with PCL sacrifice and found no significant difference in patient-reported outcomes between paired TKAs with and without CPAK type recreation accompanied by JLO restoration. In the present study, substantial difference in the degree of JLO preservation were observed between paired bilateral PS-TKAs, despite using the same surgical technique. This may primarily be attributed to the inconsistent positioning of the intramedullary rod during femoral valgus resection, which is the inherent limitation of manual TKA [ 18 , 19 ]. In our procedure, the femur was resected first, and bony adjustments were prioritized to achieve gap balancing. An unintentional varus distal femur cut led to a compensatory valgus tibia cut, resulting in a JLO with a more proximal apex direction. Conversely, when the distal femur was resected in neutral alignment, varus tibia cut was used to achieve gap balancing (because most preoperative knees exhibit varus alignment), yielding a JLO with a more distal apex direction. Given that most knees had a distal apex JLO direction preoperatively, the latter scenario would result in less alteration of the JLO and better preservation of both the CPAK type and JLO direction. Based on previous studies advocating for JLO preservation, superior clinical outcomes would be expected in the S-ΔJLO knees, where the latter scenario was implemented. However, the preference rate and patient reported outcomes were found to be similar between the G- and S-ΔJLO knees. Interestingly, 65.6% of patients (31.2% of patients were satisfied with bilateral TKAs without preference and 34.3% of patients preferred TKAs with greater JLO change) were satisfied with or preferred TKAs with greater JLO change. Replicating the native anatomy may not play a critical role in the clinical outcomes of PS TKA sacrificing the PCL, which is an important structure contributing to native knee kinematics [ 7 ]. Song et al. [ 15 ] also reported comparable clinical outcomes, including patient preference between paired PS TKAs with an anterior tibial slope, which deviates significantly from the native anatomy, and those with a more anatomical PTS, after a minimum follow-up of 5 years. From this perspective, JLO preservation would not have a significant effect on the clinical outcomes of PS TKA. Patients’ satisfaction after TKA is significantly affected by various personal factors [ 8 – 10 , 20 ]. A recent systematic review described personal factors, such as pain catastrophizing and psychological disorders, as key determinants of patient satisfaction post-TKA [ 20 ]. Therefore, evaluating paired PS TKAs in a manner that controls for personal factors will offer a clearer understanding of the clinical impact of JLO preservation. Based on our results, JLO preservation does not appear to be a critical factor in improving patient satisfaction with PS TKA. This study has several limitations. First, this study is retrospective in design, as prospectively performing paired TKAs with markedly different JLO changes in a single patient would have been virtually impossible and ethically unacceptable. Second, although patients’ clinical outcomes usually stabilized in the second year after TKA, the follow-up period was relatively short. Third, our operative procedure was performed based on mechanical alignment, which is not optimal for restoring native anatomy. Although S-ΔJLO knees showed better JLO preservation, neither group sufficiently reproduced the preoperative CPAK type and JLO direction, which may have contributed to the comparable clinical outcomes. Fourth, the present study did not evaluate changes in the JLO in the three dimensions. In addition to coronal alignment changes, alterations in the axial and sagittal planes may also affect postoperative outcomes. Fifth, not all the confounding factors were thoroughly controlled. For example, the potential impact of spinal or hip disorders on patient preferences could not be precisely evaluated. Finally, despite the assessment of various patient-reported outcomes, joint awareness–specific measures such as the Forgotten Knee Score were not evaluated. Conclusion The degree of JLO preservation did not significantly affect clinical outcomes of PS TKAs. JLO preservation will not be a critical factor in improving patient satisfaction for PS TKA. Abbreviations aHKA, arithmetic hip knee ankle angle CPAK, Coronal Plane Alignment of the Knee CR, cruciate-retaining HSS, Hospital for Special Surgery, JLO, joint line obliquity mLDFA, mechanical lateral distal femoral angle mMPTA, mechanical medial proximal tibial angle PCL, posterior cruciate ligament PS, posterior stabilized PACS, Picture Archiving and Communication System PTS, posterior tibial slope ROM, range of motion TKA, total knee arthroplasty WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index Declarations Funding No external funding was used for this retrospective study. Human Ethics and Consent to Participate declarations This study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Informed consent was obtained from all of the patients before commencing the review. IRB approval The study was approved by the institutional review boards of our institutions. References Clark G, Steer R, Wood D (2023) Functional alignment achieves a more balanced total knee arthroplasty than either mechanical alignment or kinematic alignment prior to soft tissue releases. Knee Surg Sports Traumatol Arthrosc 31 (4):1420-1426 Clark GW, Steer RA, Khan RN, Collopy DM, Wood D (2023) Maintaining Joint Line Obliquity Optimizes Outcomes of Functional Alignment in Total Knee Arthroplasty in Patients With Constitutionally Varus Knees. J Arthroplasty 38 (7 Suppl 2):S239-S244 van de Graaf VA, Clark GW, Collopy D, Wood JA, Chen DB, MacDessi SJ (2024) Functional alignment minimizes changes to joint line obliquity in robotic-assisted total knee arthroplasty: a CT analysis of functional versus kinematic alignment in 2,116 knees using the Coronal Plane Alignment of the Knee (CPAK) classification. 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Ann Jt 7 35 Haruta Y, Kawahara S, Tsuchimochi K, Hamasaki A, Hara T (2018) Deviation of femoral intramedullary alignment rod influences coronal and sagittal alignment during total knee arthroplasty. Knee 25 (4):644-649 DeFrance MJ, Scuderi GR (2023) Are 20% of Patients Actually Dissatisfied Following Total Knee Arthroplasty? A Systematic Review of the Literature. J Arthroplasty 38 (3):594-599 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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-7104332","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":488902315,"identity":"142a010e-ca62-4b5f-9d7a-3db0ccb669bc","order_by":0,"name":"Sang Jun Song","email":"","orcid":"","institution":"Kyung Hee University","correspondingAuthor":false,"prefix":"","firstName":"Sang","middleName":"Jun","lastName":"Song","suffix":""},{"id":488902316,"identity":"a91e341f-3622-46ea-bfc6-2ac520b731ac","order_by":1,"name":"Young Kook Kim","email":"","orcid":"","institution":"Kyung Hee University","correspondingAuthor":false,"prefix":"","firstName":"Young","middleName":"Kook","lastName":"Kim","suffix":""},{"id":488902317,"identity":"59162a95-ba83-42c9-8196-c3bb1b2ca488","order_by":2,"name":"Cheol Hee Park","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5UlEQVRIiWNgGAWjYDACCRBxQEKOn+HwARBXhlgtNsaSjccSQFweYrWkJW44fMYAxCSshX9278HPFWcOMzYcO/P51Y0aCx4G9sNHN+C15M65ZMkzNw4zM/ac3WadcwzoMJ60tBv4tBhI5BhINnw4zMYscXabcQ4bUIsEjxkhLcY/gVp42OTfPDPO+UecFjPJhhtpQKVnmB/nthGhReJGXpplwxkbAwmGY2bMuX0SPGyE/MI/I/fwzYZjEvX7Dxx+/DnnW50cP/vhY3i1IEcEGziO2PArR9XC/IGw6lEwCkbBKBiJAADqV01uYZp9XgAAAABJRU5ErkJggg==","orcid":"","institution":"Kyung Hee University","correspondingAuthor":true,"prefix":"","firstName":"Cheol","middleName":"Hee","lastName":"Park","suffix":""}],"badges":[],"createdAt":"2025-07-11 20:08:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7104332/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7104332/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":87700720,"identity":"90581b44-ff7a-44d8-a14b-c1dc4db30867","added_by":"auto","created_at":"2025-07-28 07:19:13","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":70200,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003ePreoperative and postoperative distribution of the Coronal Plane Alignment of the Knee types and direction of joint line obliquity\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eG-ΔJLO, TKAs with a greater change in the joint line obliquity; S-ΔJLO, TKAs with a smaller change in the joint line obliquity; CPAK, Coronal Plane Alignment of the Knee; JLO, joint line obliquity\u003c/p\u003e","description":"","filename":"Fig1A600dpi.png","url":"https://assets-eu.researchsquare.com/files/rs-7104332/v1/a1c40b6246908efd5b57f5d1.png"},{"id":96841609,"identity":"c4ab38e8-5b4f-46ce-8057-b1badaaf2e98","added_by":"auto","created_at":"2025-11-26 15:53:47","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":648908,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7104332/v1/5cebf882-f27a-4b51-abda-156ce57edab5.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Preservation of joint line obliquity is not a critical factor for improving patient satisfaction","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePreservation of joint line obliquity (JLO) has recently garnered attention as a potential factor improving patient satisfaction after total knee arthroplasty (TKA) [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Previous studies have suggested that JLO preservation contributes to better restoration of native knee kinematics and enhances clinical outcomes [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. However, these studies primarily investigated cruciate-retaining (CR) TKAs, which preserves the posterior cruciate ligament (PCL), an important structure for replicating native knee kinematics. In posterior-stabilized (PS) TKA, which involves removal of PCL and thereby limits the ability to replicate natural knee kinematics, the preservation of the JLO may have limited clinical impact [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eMultiple factors influence patient satisfaction after TKA, among which preoperative expectations, psychological factors, pain sensitivity, and lifestyle inevitably vary from person to person [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Most studies analyzing the relationship between JLO preservation and clinical outcomes have not rigorously controlled for these factors [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Given this limitation, a more reliable assessment of the effects of JLO preservation can be achieved by analyzing patient preference in TKAs performed on paired knees using the same prosthesis but with significantly different degrees of JLO preservation.\u003c/p\u003e\u003cp\u003eThis study aimed to evaluate the clinical outcomes, including patient preferences, in paired bilateral PS TKAs performed with the same prosthesis but with significantly different degrees of JLO change. Our hypothesis was that the degree of JLO preservation would not significantly influence the clinical outcomes in PS TKAs.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003e\u003cb\u003ePatients\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThis retrospective study included patients who underwent 1-week staged bilateral primary TKA using either Attune\u0026reg; (Depuy Synthes, Warsaw, IN, USA) or Persona\u0026reg; (Zimmer, Warsaw, IN, USA) PS prosthesis at our hospital between January 2018 and December 2022. All surgeries were performed by a senior surgeon who had had surgical experience with over 5,000 TKAs before the study period.\u003c/p\u003e\u003cp\u003ePatients were included if the met the following criteria: (1) bilateral Kellgren\u0026ndash;Lawrence grade 4 degenerative osteoarthritis preoperatively; (2) similar preoperative arithmetic hip-knee-ankle angle (aHKA) and JLO between paired knees, defined as absolute differences\u0026thinsp;\u0026le;\u0026thinsp;2\u0026deg; and \u0026le;\u0026thinsp;3\u0026deg;, respectively [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]; (3) paired TKAs with significantly different postoperative JLO changes (difference\u0026thinsp;\u0026gt;\u0026thinsp;3\u0026deg; between greater and smaller JLO change) [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]; (4) a minimum follow-up period of 2 years; and (5) availability of clinical and radiographic data before and after surgery. Exclusion criteria included: (1) inflammatory arthritis; (2) a history of femoral or tibial fracture, knee dislocation, or ligament injury; (3) a history of distal femoral or high tibial osteotomy; and (4) presence of femoral and tibial diaphyseal deformity. Based on these criteria, 128 patients were included in this study.\u003c/p\u003e\u003cp\u003eThe patient demographics are presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. No significant differences were observed regarding preoperative clinical and radiographic knee conditions between paired TKAs with greater JLO change (Greater-ΔJLO knees) and smaller JLO change (Smaller-ΔJLO knees) (Tables\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e and \u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This study was approved by the Institutional Review Board of our institution. Informed consent was obtained from all of the patients before commencing the review.\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\u003e\u003cb\u003ePatient demographics\u003c/b\u003e\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\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\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eOperating period\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eJan 2018\u0026ndash; Dec 2022\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eNumber of patients\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e128\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eAge*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e71.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.0\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFemale/Male\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e120 / 8\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eBody mass index (kg/m\u003csup\u003e2\u003c/sup\u003e)*\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e26.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eType of Prostheses (Attune\u0026reg;/ Persona\u0026reg;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e68 / 60\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFollow-up period (year)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e3.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"2\"\u003e* Continuous variables are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation.\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=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eRadiographic results\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eG-ΔJLO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eS-ΔJLO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003ep-value\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003emLDFA (\u0026deg;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e89.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e89.7\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.148\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePostoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e92.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e90.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003emMPTA (\u0026deg;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e84.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e84.0\u0026thinsp;\u0026plusmn;\u0026thinsp;2.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.881\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePostoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e91.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e88.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003eaHKA (\u0026deg;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e-5.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e-5.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.418\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePostoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e-1.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e-2.5\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.002\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChange\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e3.6\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e3.1\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.261\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eJLO (\u0026deg;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e173.4\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e173.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.130\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePostoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e183.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e179.2\u0026thinsp;\u0026plusmn;\u0026thinsp;2.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChange\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e10.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e5.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\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\u003ePTS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e10.7\u0026thinsp;\u0026plusmn;\u0026thinsp;3.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e10.9\u0026thinsp;\u0026plusmn;\u0026thinsp;3.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.199\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePostoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e3.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e3.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.5\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.471\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eChange\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e7.4\u0026thinsp;\u0026plusmn;\u0026thinsp;4.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e7.5\u0026thinsp;\u0026plusmn;\u0026thinsp;3.9\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.789\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eData are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation.\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eG-ΔJLO, TKAs with a greater change in the joint line obliquity; S-ΔJLO, TKAs with a smaller change in the joint line obliquity; mLDFA, mechanical lateral distal femoral angle; mMPTA, mechanical medial proximal tibial angle; aHKA, arithmetic hip-knee-ankle angle; JLO, joint line obliquity; PTS, posterior tibial slope.\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\u003eClinical results\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eG-ΔJLO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eS-ΔJLO\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\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\u003eHSS\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e37.1\u0026thinsp;\u0026plusmn;\u0026thinsp;6.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e37.5\u0026thinsp;\u0026plusmn;\u0026thinsp;7.6\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.249\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLast follow-up\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e93.2\u0026thinsp;\u0026plusmn;\u0026thinsp;5.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e92.9\u0026thinsp;\u0026plusmn;\u0026thinsp;5.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.540\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eWOMAC\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e68.2\u0026thinsp;\u0026plusmn;\u0026thinsp;3.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e67.8\u0026thinsp;\u0026plusmn;\u0026thinsp;4.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.155\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLast follow-up\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e9.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.0\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e9.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.8\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.307\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eRange of motion (\u0026deg;)\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003ePreoperative\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e116.8\u0026thinsp;\u0026plusmn;\u0026thinsp;17.2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e118.3\u0026thinsp;\u0026plusmn;\u0026thinsp;20.7\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.291\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLast follow-up\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e\u003cp\u003e130.0\u0026thinsp;\u0026plusmn;\u0026thinsp;15.1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c4\"\u003e\u003cp\u003e128.8\u0026thinsp;\u0026plusmn;\u0026thinsp;15.4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e0.116\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003ctfoot\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eData are presented as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd colspan=\"5\"\u003eG-ΔJLO, TKAs with a greater change in the joint line obliquity; S-ΔJLO, TKAs with a smaller change in the joint line obliquity; HSS, Hospital for Special Surgery; WOMAC, the Western Ontario and McMaster Universities osteoarthritis index\u003c/td\u003e\u003c/tr\u003e\u003c/tfoot\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003e\u003cb\u003eSurgical techniques and rehabilitation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAll TKAs were performed using a tourniquet control. A medial parapatellar approach was used with a midline skin incision. An intramedullary guide was used for distal femoral resection. The distal femoral cut was performed at valgus angles of 4\u0026deg;, 5\u0026deg;, and 6\u0026deg;, using the intramedullary rod as a reference, corresponding to preoperative long-leg radiographic measurements of the angle between the femoral anatomical and mechanical axes of \u0026lt;\u0026thinsp;5\u0026deg;, 5\u0026deg;\u0026ndash;7\u0026deg;, and \u0026gt;\u0026thinsp;7\u0026deg;, respectively. The transepicondylar axis was used for determining the femoral component rotation. An extramedullary guide was used for tibial resection, with the initial cutting plane positioned perpendicular to the mechanical tibial axis. The posterior tibial slope (PTS) was set at 3\u0026deg; in the sagittal plane, guided by a reference line connecting the fibular head and lateral malleolus. Tibial component rotation was determined using a reference line connecting the medial third of the tibial tubercle to the insertion point of the PCL.\u003c/p\u003e\u003cp\u003eFollowing resection, trial implants were inserted. Mediolateral and flexion-extension balancing was achieved through bony adjustment prior to any soft tissue release. For mediolateral balancing, modification of the tibial cutting plane was prioritized. The coronal alignment of the cutting plane was adjusted within the range of varus 3\u0026deg; to valgus 3\u0026deg;. Flexion-extension gap balancing was achieved by modifying the tibial slope within the range of 0\u0026deg; to 6\u0026deg;[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. If imbalance persisted despite adjustments being made to the bony cutting plane, selective release of the contracted soft tissue was performed.\u003c/p\u003e\u003cp\u003eThe appropriate thickness of the polyethylene insert was determined by considering stability and kinematics with proper ligament tension and physiological knee motion without hyperextension, flexion contracture, or lift-off of the trial insert. Patellar resurfacing was performed. All components were implanted on cleaned and dried cut surfaces using a full cementation technique.\u003c/p\u003e\u003cp\u003eIsometric exercises using the extensor and flexor muscles were initiated shortly after the operation. The drain was removed on the first postoperative day, followed by initiation of active and assisted range of motion (ROM) exercises. Weight-bearing ambulation was also initiated on the first operative day, as tolerated by the patients.\u003c/p\u003e\u003cp\u003e\u003cb\u003eRadiographic evaluation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe radiographic parameters were measured preoperatively and at the final follow-up visit. Preoperative and postoperative long-leg standing anteroposterior radiograph and lateral knee radiograph were obtained under weight-bearing conditions.\u003c/p\u003e\u003cp\u003eThe mechanical lateral distal femoral angle (mLDFA), mechanical medial proximal tibial angle (mMPTA), aHKA, and JLO were measured on long-leg standing anteroposterior radiographs in accordance with the Coronal Plane Alignment of the Knee (CPAK) classification system [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. mLDFA was defined as the lateral angle between the femoral mechanical axis and the tangent line of the most distal points of the femoral condyles in the native knee or implant. mMPTA was defined as the medial angle between the tibial mechanical axis and the tangent line of the native proximal tibial plateau or the tibial baseplate. aHKA was defined as the value obtained by subtracting mLDFA from mMPTA, whereas JLO was defined as the sum of mMPTA and mLDFA. PTS was measured using lateral knee radiographs [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Preoperative PTS was defined as the angle between the perpendicular line of the tibial intramedullary canal axis and the line connecting the anterior and posterior borders of the medial tibial plateau. For the measurement of the postoperative PTS, the tibial cutting surface was used.\u003c/p\u003e\u003cp\u003eRadiographic quality was ensured by standardizing knee positioning and maintaining a consistent distance between the X-ray beam and cassette. All images were digitally transferred to a Picture Archiving and Communication System (PACS). Angular measurements were performed using PACS software, with a minimum detectable angular difference of 0.1\u0026deg;.\u003c/p\u003e\u003cp\u003eIn order to minimize any observational bias, two independent investigators performed all radiographic measurements. The interobserver reliabilities of all measurements were assessed using the intraclass correlation coefficient, and all values were greater than 0.8. Therefore, the average values obtained by the two investigators were used for analysis.\u003c/p\u003e\u003cp\u003e\u003cb\u003eClinical evaluation\u003c/b\u003e\u003c/p\u003e\u003cp\u003eThe clinical outcomes were evaluated preoperatively and at the final follow-up visit. Patient preference between paired TKAs with greater and smaller JLO changes was investigated. The Hospital for Special Surgery score (HSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and ROM were evaluated. The ROM was measured using a long-armed goniometer.\u003c/p\u003e\u003cp\u003e\u003cb\u003eComplications\u003c/b\u003e\u003c/p\u003e\u003cp\u003eAny complications were investigated according to the standardized list and definitions of complications provided by the Knee Society [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eStatistical analysis\u003c/h2\u003e\u003cp\u003eThe pre- and postoperative radiographic variables and clinical scores were compared between G- and S-ΔJLO knees using paired t-tests. The proportion of CPAK type and JLO direction (apex distal, neutral, and apex proximal) were compared between the G- and S-ΔJLO knees using Wilcoxon signed-rank test. The maintenance rates of CPAK type and JLO direction, as well as the preference rates, were compared using the McNemar test. All statistical analyses were performed using SPSS version 25.0 (Chicago, IL, USA). A p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e\u003cp\u003ePower analysis was performed to determine the minimum sample size required for sufficient statistical power in evaluating patient preference. This analysis was based on a hypothesis of non-inferiority between G- and S-ΔJLO knees, with a clinically acceptable difference in preference rate set at 20% [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. The alpha level was set at 0.05, and the desired power was 80%. The performed power analysis indicated that \u0026gt;\u0026thinsp;70 patients were required for each group to ensure sufficient statistical power.\u003c/p\u003e\u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eRadiographically, no significant differences were observed in preoperative variables between the G- and S-ΔJLO knees (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Postoperatively, the femoral component showed more varus alignment in the G-ΔJLO knees, whereas the tibial component showed more varus alignment in the S-ΔJLO knees (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The average postoperative aHKA exhibited a more varus alignment in the S-ΔJLO knees; however, the mean change in aHKA between the two groups was not significantly different (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The average postoperative JLO displayed a more apex proximal obliquity in the G-ΔJLO knees (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The average JLO changes were 10.5\u0026deg; in the G-ΔJLO knees and 5.5\u0026deg; in the S-ΔJLO knees (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The preoperative and postoperative PTS and changes in PTS were not significantly different (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eThe postoperative proportions of CPAK type and JLO direction after surgery differed significantly (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 for both) between the G- and S-ΔJLO knees, although the preoperative portions were not significantly different (p\u0026thinsp;=\u0026thinsp;0.184 and 0.102, respectively) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Maintenance of the original CPAK type was observed in 0 case in the G-ΔJLO knees and in 20 cases (15.6%) in the S-ΔJLO knees (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The direction of JLO was maintained in 0 case in the G-ΔJLO knees and in 37 cases (28.9%) in the S-ΔJLO knees (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eClinically, regarding preference, 40 patients (31.2%) were satisfied with bilateral TKAs without a specific preference, while 44 patients (34.3%) preferred TKAs of the G-ΔJLO knee and 44 patients (34.3%) preferred the S-ΔJLO knee; no significant difference was observed in the preference rates between the groups (p\u0026thinsp;=\u0026thinsp;1.000). Additionally, no significant differences were found in the HSS, WOMAC, and ROM between the G- and S-ΔJLO knees at the last follow-up (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\u003cp\u003eNo complications were reported in either the G- or S-ΔJLO knees during the follow-up period.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe most important finding of the present study was that clinical outcomes were comparable between paired bilateral PS TKAs with greater and smaller JLO changes at an average 3.9 years of follow-up. The degree of JLO preservation did not affect patient preference for PS TKAs.\u003c/p\u003e\u003cp\u003ePrevious studies involving CR TKAs have shown that JLO preservation is a crucial factor in optimizing clinical outcomes and improving patient satisfaction. Winnock de Grave et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] reported that JLO preservation resulted in gait pattern similar to those of healthy native knees without increasing knee adduction moments after CR TKA. Clark et al. [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] reported that robot-assisted CR TKAs with better JLO preservation achieved higher Forgotten Joint Score-12 scores and greater ROM than those with less JLO preservation.\u003c/p\u003e\u003cp\u003eHowever, other studies have challenged the advantages of JLO preservation in TKA designs that sacrifice the PCL. Recent gait analyses have shown that restoring the pre-arthritic joint line does not necessarily replicate native knee kinematics in TKA using a medially stabilized design with PCL sacrifice [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Rodriguez et al [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. analyzed 23 pairs of bilateral paired TKAs with PCL sacrifice and found no significant difference in patient-reported outcomes between paired TKAs with and without CPAK type recreation accompanied by JLO restoration.\u003c/p\u003e\u003cp\u003eIn the present study, substantial difference in the degree of JLO preservation were observed between paired bilateral PS-TKAs, despite using the same surgical technique. This may primarily be attributed to the inconsistent positioning of the intramedullary rod during femoral valgus resection, which is the inherent limitation of manual TKA [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. In our procedure, the femur was resected first, and bony adjustments were prioritized to achieve gap balancing. An unintentional varus distal femur cut led to a compensatory valgus tibia cut, resulting in a JLO with a more proximal apex direction. Conversely, when the distal femur was resected in neutral alignment, varus tibia cut was used to achieve gap balancing (because most preoperative knees exhibit varus alignment), yielding a JLO with a more distal apex direction. Given that most knees had a distal apex JLO direction preoperatively, the latter scenario would result in less alteration of the JLO and better preservation of both the CPAK type and JLO direction.\u003c/p\u003e\u003cp\u003eBased on previous studies advocating for JLO preservation, superior clinical outcomes would be expected in the S-ΔJLO knees, where the latter scenario was implemented. However, the preference rate and patient reported outcomes were found to be similar between the G- and S-ΔJLO knees. Interestingly, 65.6% of patients (31.2% of patients were satisfied with bilateral TKAs without preference and 34.3% of patients preferred TKAs with greater JLO change) were satisfied with or preferred TKAs with greater JLO change.\u003c/p\u003e\u003cp\u003eReplicating the native anatomy may not play a critical role in the clinical outcomes of PS TKA sacrificing the PCL, which is an important structure contributing to native knee kinematics [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Song et al. [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] also reported comparable clinical outcomes, including patient preference between paired PS TKAs with an anterior tibial slope, which deviates significantly from the native anatomy, and those with a more anatomical PTS, after a minimum follow-up of 5 years. From this perspective, JLO preservation would not have a significant effect on the clinical outcomes of PS TKA.\u003c/p\u003e\u003cp\u003ePatients\u0026rsquo; satisfaction after TKA is significantly affected by various personal factors [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. A recent systematic review described personal factors, such as pain catastrophizing and psychological disorders, as key determinants of patient satisfaction post-TKA [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Therefore, evaluating paired PS TKAs in a manner that controls for personal factors will offer a clearer understanding of the clinical impact of JLO preservation. Based on our results, JLO preservation does not appear to be a critical factor in improving patient satisfaction with PS TKA.\u003c/p\u003e\u003cp\u003eThis study has several limitations. First, this study is retrospective in design, as prospectively performing paired TKAs with markedly different JLO changes in a single patient would have been virtually impossible and ethically unacceptable. Second, although patients\u0026rsquo; clinical outcomes usually stabilized in the second year after TKA, the follow-up period was relatively short. Third, our operative procedure was performed based on mechanical alignment, which is not optimal for restoring native anatomy. Although S-ΔJLO knees showed better JLO preservation, neither group sufficiently reproduced the preoperative CPAK type and JLO direction, which may have contributed to the comparable clinical outcomes. Fourth, the present study did not evaluate changes in the JLO in the three dimensions. In addition to coronal alignment changes, alterations in the axial and sagittal planes may also affect postoperative outcomes. Fifth, not all the confounding factors were thoroughly controlled. For example, the potential impact of spinal or hip disorders on patient preferences could not be precisely evaluated. Finally, despite the assessment of various patient-reported outcomes, joint awareness\u0026ndash;specific measures such as the Forgotten Knee Score were not evaluated.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe degree of JLO preservation did not significantly affect clinical outcomes of PS TKAs. JLO preservation will not be a critical factor in improving patient satisfaction for PS TKA.\u003c/p\u003e"},{"header":"Abbreviations\t","content":"\u003cp\u003eaHKA, arithmetic hip knee ankle angle\u003c/p\u003e\n\u003cp\u003eCPAK, Coronal Plane Alignment of the Knee\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCR, cruciate-retaining\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHSS, Hospital for Special Surgery,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eJLO, joint line obliquity\u0026nbsp;\u003c/p\u003e\n\u003cp\u003emLDFA, mechanical lateral distal femoral angle\u0026nbsp;\u003c/p\u003e\n\u003cp\u003emMPTA, mechanical medial proximal tibial angle\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePCL, posterior cruciate ligament\u003c/p\u003e\n\u003cp\u003ePS, posterior stabilized\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ePACS, Picture Archiving and Communication System\u003c/p\u003e\n\u003cp\u003ePTS, posterior tibial slope\u003c/p\u003e\n\u003cp\u003eROM, range of motion\u003c/p\u003e\n\u003cp\u003eTKA, total knee arthroplasty\u003c/p\u003e\n\u003cp\u003eWOMAC, Western Ontario and McMaster Universities Osteoarthritis Index\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNo external funding was used for this retrospective study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eHuman Ethics and Consent to Participate declarations\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. Informed consent was obtained from all of the patients before commencing the review.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eIRB approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study was approved by the institutional review boards of our institutions.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eClark G, Steer R, Wood D (2023) Functional alignment achieves a more balanced total knee arthroplasty than either mechanical alignment or kinematic alignment prior to soft tissue releases. Knee Surg Sports Traumatol Arthrosc 31 (4):1420-1426\u003c/li\u003e\n \u003cli\u003eClark GW, Steer RA, Khan RN, Collopy DM, Wood D (2023) Maintaining Joint Line Obliquity Optimizes Outcomes of Functional Alignment in Total Knee Arthroplasty in Patients With Constitutionally Varus Knees. J Arthroplasty 38 (7 Suppl 2):S239-S244\u003c/li\u003e\n \u003cli\u003evan de Graaf VA, Clark GW, Collopy D, Wood JA, Chen DB, MacDessi SJ (2024) Functional alignment minimizes changes to joint line obliquity in robotic-assisted total knee arthroplasty: a CT analysis of functional versus kinematic alignment in 2,116 knees using the Coronal Plane Alignment of the Knee (CPAK) classification. Bone Jt Open 5 (12):1081-1091\u003c/li\u003e\n \u003cli\u003eWinnock de Grave P, Van Criekinge T, Luyckx T, Moreels R, Gunst P, Claeys K (2023) Restoration of the native tibial joint line obliquity in total knee arthroplasty with inverse kinematic alignment does not increase knee adduction moments. Knee Surg Sports Traumatol Arthrosc 31 (11):4692-4704\u003c/li\u003e\n \u003cli\u003eRodriguez AO, Jagota I, Bare J, Shimmin A (2025) Impact of changes in native coronal plane alignment of the knee (CPAK) on patient-reported outcome measures (PROMS). A bilateral single implant study. J Orthop 65 64-70\u003c/li\u003e\n \u003cli\u003eSalvi AG, Valpiana P, Innocenti B, Ghirardelli S, Bernardi M, Petralia G, Aloisi G, Zepeda K, Schaller C, Indelli PF (2024) The Restoration of the Prearthritic Joint Line Does Not Guarantee the Natural Knee Kinematics: A Gait Analysis Evaluation Following Primary Total Knee Arthroplasty. Arthroplast Today 30 101586\u003c/li\u003e\n \u003cli\u003eSong SJ, Kim KI, Park CH (2022) Sensor Use in Cruciate-Retaining Total Knee Arthroplasty Compared with Posterior-Stabilized Total Knee Arthroplasty: Load Balancing and Posterior Femoral Rollback. J Knee Surg 35 (12):1349-1356\u003c/li\u003e\n \u003cli\u003eSorel JC, Veltman ES, Honig A, Poolman RW (2019) The influence of preoperative psychological distress on pain and function after total knee arthroplasty: a systematic review and meta-analysis. Bone Joint J 101-B (1):7-14\u003c/li\u003e\n \u003cli\u003eRedfern RE, Crawford DA, Lombardi AV, Jr., Tripuraneni KR, Van Andel DC, Anderson MB, Cholewa JM (2023) Outcomes Vary by Pre-Operative Physical Activity Levels in Total Knee Arthroplasty Patients. J Clin Med 13 (1):\u003c/li\u003e\n \u003cli\u003eStuhlreyer J, Klinger R (2022) The Influence of Preoperative Mood and Treatment Expectations on Early Postsurgical Acute Pain After a Total Knee Replacement. Front Psychiatry 13 840270\u003c/li\u003e\n \u003cli\u003eRames RD, Mathison M, Meyer Z, Barrack RL, Nam D (2018) No impact of under-correction and joint line obliquity on clinical outcomes of total knee arthroplasty for the varus knee. Knee Surg Sports Traumatol Arthrosc 26 (5):1506-1514\u003c/li\u003e\n \u003cli\u003eSappey-Marinier E, Batailler C, Swan J, Schmidt A, Cheze L, MacDessi SJ, Servien E, Lustig S (2022) Mechanical alignment for primary TKA may change both knee phenotype and joint line obliquity without influencing clinical outcomes: a study comparing restored and unrestored joint line obliquity. Knee Surg Sports Traumatol Arthrosc 30 (8):2806-2814\u003c/li\u003e\n \u003cli\u003eTarassoli P, Warnock JM, Lim YP, Jagota I, Parker D (2024) Large multiplanar changes to native alignment have no apparent impact on clinical outcomes following total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 32 (2):432-444\u003c/li\u003e\n \u003cli\u003eMacDessi SJ, Griffiths-Jones W, Harris IA, Bellemans J, Chen DB (2021) Coronal Plane Alignment of the Knee (CPAK) classification. Bone Joint J 103-B (2):329-337\u003c/li\u003e\n \u003cli\u003eSong SJ, Bae DK, Hwang SH, Park HS, Park CH (2024) Similar Midterm Outcomes of Total Knee Arthroplasties with Anterior and Posterior Tibial Slopes Performed on Paired Knees at a Minimum Follow-up of 5 Years. J Knee Surg 37 (4):310-315\u003c/li\u003e\n \u003cli\u003eHealy WL, Della Valle CJ, Iorio R, Berend KR, Cushner FD, Dalury DF, Lonner JH (2013) Complications of total knee arthroplasty: standardized list and definitions of the Knee Society. Clin Orthop Relat Res 471 (1):215-220\u003c/li\u003e\n \u003cli\u003eGunaratne R, Pratt DN, Banda J, Fick DP, Khan RJK, Robertson BW (2017) Patient Dissatisfaction Following Total Knee Arthroplasty: A Systematic Review of the Literature. J Arthroplasty 32 (12):3854-3860\u003c/li\u003e\n \u003cli\u003eSong SJ, Lee HW, Kim YK, Park CH (2022) Fixed distal femoral resection with a valgus cutting angle of 3 degrees is more appropriate in intra-articular valgus deformity than juxta-articular valgus deformity in total knee arthroplasty: a retrospective single center study. Ann Jt 7 35\u003c/li\u003e\n \u003cli\u003eHaruta Y, Kawahara S, Tsuchimochi K, Hamasaki A, Hara T (2018) Deviation of femoral intramedullary alignment rod influences coronal and sagittal alignment during total knee arthroplasty. Knee 25 (4):644-649\u003c/li\u003e\n \u003cli\u003eDeFrance MJ, Scuderi GR (2023) Are 20% of Patients Actually Dissatisfied Following Total Knee Arthroplasty? A Systematic Review of the Literature. J Arthroplasty 38 (3):594-599\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Knee, Total knee arthroplasty, Posterior stabilized, Joint line obliquity, Satisfaction","lastPublishedDoi":"10.21203/rs.3.rs-7104332/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7104332/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose: \u003c/strong\u003eThis study has aimed to evaluate the clinical outcomes in paired bilateral posterior stabilized (PS) TKAs with significantly different degrees of joint line obliquity (JLO) change.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eA retrospective review was conducted on 128 patients who underwent paired bilateral PS TKAs, with greater and smaller JLO changes (G-ΔJLO and S-ΔJLO knees; difference between greater and smaller JLO change \u0026gt;3°). The mean follow-up period was 3.9 years (minimum 2 years). Radiographic changes in JLO were measured according to the Coronal Plane Alignment of the Knee (CPAK) classification. Maintenance of the CPAK type and JLO direction (apex distal, neutral, and apex proximal) was investigated. Clinically, the preferred TKA out of greater and smaller JLO changes was investigated.\u003cstrong\u003e \u003c/strong\u003eThe Hospital for Special Surgery and Western Ontario and McMaster Universities Osteoarthritis Index were evaluated.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eThe average JLO change was 10.5° in the G-ΔJLO knees and 5.5° in the S-ΔJLO knees (p \u0026lt; 0.001). The CPAK type and JLO direction was better maintained in the S-ΔJLO knees (p \u0026lt; 0.001, repsectively). Regarding preference, 40 patients (31.2%) were satisfied with bilateral TKAs without a specific preference, while 44 patients (34.3%) preferred TKAs of the G-ΔJLO knee and 44 patients (34.3%) preferred the S-ΔJLO knee (p = 1.000). No significant differences were found in the patient reported outcomes between the G- and S-ΔJLO knees.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusion:\u003c/strong\u003e The degree of JLO preservation did not significantly affect clinical outcomes of PS TKAs. JLO preservation will not be a critical factor in improving patient satisfaction for PS TKA.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eLevel of evidence: \u003c/strong\u003eIII\u003c/p\u003e","manuscriptTitle":"Preservation of joint line obliquity is not a critical factor for improving patient satisfaction","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-28 07:19:08","doi":"10.21203/rs.3.rs-7104332/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"4cb85b5f-5f42-4806-9850-9bdaf395e2f5","owner":[],"postedDate":"July 28th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-11-26T15:53:21+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-28 07:19:08","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7104332","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7104332","identity":"rs-7104332","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}