The Medial Pivot design achieves better sagittal plane balance in the restricted kinematic alignment total knee arthroplasty

The Medial Pivot design achieves better sagittal plane balance in the restricted kinematic alignment total knee arthroplasty | 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 The Medial Pivot design achieves better sagittal plane balance in the restricted kinematic alignment total knee arthroplasty Mingyang Ma, Sen Liu, Yang Yu, Zhongyin Ji, Hongjun Xu, Guiguan Wang, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9201898/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 Introduction: Achieving sagittal plane balance is important to total knee arthroplasty (TKA) for providing mid-flexion stability and potentially increasing patient’s satisfaction. This study aimed to compare the sagittal plane parameters, range of motion (ROM), and patient-reported outcomes (PROMs) between patients received the cruciate retaining (CR) and the patients received medial-pivot (MP) in the restricted kinematic alignment TKA. Methods This retrospective study including a total of 124 patients who underwent TKA in Department of Orthopedics of Peking Union Medical College Hospital between February 2024 and January 2025. Patients were assessed preoperatively and 12 months postoperatively. All patients taken X-ray imaging in pre-operation and on the third day after the operation. Clinical assessments including the Forgotten Joint Score (FJS), physical examination including the assessment of the active ROM of the knee. The HKA (Hip-Knee-Angle), LDFA (Lateral Distal Femoral Angle), MPTA (Medial Proximal Tibial Angle), LFCA (Lateral Femoral Component Angle), LTCA (Lateral Tibial Component Angle), patella thickness, patella length, posterior femoral condylar offset (PCO), Coronal femoral width (LFW), PCO ratio, and posterior tibial slope (PTS) were taken from the X-ray imaging. Results There were 60 patients in the MP-TKA group and 64 patients in the CR-TKA group. Pre-operatively, there were no significant differences between the two groups in terms of demographic data, HKA, LDFA, MPTA, sagittal plane parameters, and FJS (p > 0.05). The MP group was more advantageous in changes of PCO (MP group changes of PCO: 2.42 ± 1.52 mm vs CR group changes of PCO: 3.62 ± 2.11 mm p < 0.001), the post-operation PCO and PCO ratio was significantly less in the MP group (MP group PCO: 26.11 ± 4.08mm vs CR group PCO: 27.65 ± 3.36mm p = 0.024; MP group PCO ratio: 0.45 ± 0.06 vs CR group PCO ratio: 0.48 ± 0.05 p = 0.001), there were no significant differences between the two groups in terms of the post-operation HKA, LDFA, MPTA and others sagittal plane parameters (p > 0.05). The post-operative ROM was significantly better in the MP group in 3-days post-operation and the 12-months post-operation (3-days post-operation in MP group:102.92°±7.93 vs 3-days post-operation in CR group:97.34°±5.49 p < 0.001, 12-months post-operation in MP group:103.35 ± 6.10 vs 12-months post-operation in CR group: 100.52 ± 4.97 p = 0.024) . Conclusion The MP design achieves better sagittal plane balance compared with the CR design TKA. total knee arthroplasty restricted kinematic alignment cruciate retaining medial-pivot Figures Figure 1 Figure 2 Figure 3 Introduction Total knee arthroplasty (TKA) is an effective treatment for alleviating the pain and improving the function of the patient's knee of the end-stage knee joint diseases. [ 1 ] The design of knee prosthesis has undergone remarkable revision and improvement since 1950, with new implant designs and refinement of surgical techniques leading to improvements in clinical outcomes. However, patient satisfaction rate after TKA is far from surgeons’ and patients’ expectations of the perfect operation, 20% of patients remain dissatisfied with their outcomes.[ 2 ] Various implant prosthesis designs, including posterior-stabilized (PS), cruciate-retaining (CR), cruciate-substitute (CS), medial-pivot (MP), and bilateral cruciate ligament preservation, have been proposed to match knees with different characteristics.[ 3 – 6 ] Although several of TKA implant designs are widely used, the ideal TKA design has not been definitively put across in the literature. There is renewed surgeons' interesting in evaluating implant designs for potential improvement in biomechanics of the knee after surgery. The classical CR design with the assumption that preserving the native posterior cruciate ligament (PCL) is advantageous in keeping knee joint proprioception, reproducing physiologic knee biomechanics, and maintaining femoral rollback. However, irregular kinematics, abnormal patellar tracking, accelerated polyethylene wear, and poor range of motion (ROM) have all been reported, which compromising patient satisfaction rate.[ 7 , 8 ] Since 1990s, the MP design has been in clinical. Kinematic research demonstrated that the natural knee functioned like a “ball and socket” joint, with the lateral femoral condyle translated in an anteroposterior direction and rotating around the medial compartment inflection. The MP is designed to replicate the biomechanics of the natural knee accurately, providing greater stability and maintaining knee flexibility. Several studies have reported favorable clinical and functional mid-term outcomes of MP knees.[ 9 , 10 ] However, reasons for consistently high rates of patient satisfaction following an MP-TKA remain poor understand. Several studies have reported that restoration of posterior femoral condylar offset (PCO) is important to achieve sagittal plane balance, providing mid-flexion stability and potentially increasing the post-operation ROM. One previous studies have shown that both an increase and a decrease in PCO will lead to mid-flexion instability, restoration of the posterior offset within a range of 2 mm is necessary to avoid mid-flexion instability.[ 11 ] Clement et al. has shown that PCO restoration correlates with improved functional outcomes after revision TKA.[ 12 ] Bellemans et al. demonstrated that restoring the PCO during TKA maximizes postoperative ROM and prevents posterior impingement.[ 13 ] Restoration of PCO is recommended in TKA. To the best of our knowledge, studies on sagittal plane parameters and ROM comparing CR and MP prosthesis are lacking. The purpose of this study was to compare the sagittal plane parameters, ROM, and patient-reported outcome measures (PROMs) between the Cruciate Retaining TKA and the Medial Pivot TKA. Patients and methods Inclusion and exclusion criteria This retrospective, single-center study was approved by the Ethics Committee of Peking Union Medical College Hospital (Approval Number: K9408), and informed consent was obtained from all participants before their inclusion in this study. All the benefits and risks of performing MP-TKA and CR-TKA are explained to patients preoperatively so they can decide which surgical procedure to perform. We analyzed patients who underwent TKA by the same operation group at the Department of Orthopedics, Peking Union Medical College Hospital, between February 2024 and January 2025. The total number of TKAs performed during the study period and the numbers of TKAs performed in both groups were showed in Fig. 1 . A total of 124 patients with knee osteoarthritis (OA) were included based on the following inclusion criteria: (1) diagnosis with primary knee OA and requiring TKA, (2) age between 50 and 85 years, and (3) with complete clinical records and radiographic data. The exclusion criteria were as follows: (1) complex primary or revision TKA, (2) inability to visualize anatomic landmarks on radiographs, (3) previous surgical history or infection history of the knee joint on the operation side; (4) the knee joint on the surgical side has suffered joint dysfunction due to factors such as nerves, muscles, psychological issues, or systemic diseases like immunity disorders. Surgical techniques All patients included in the study were categorized into the CR group and MP group depending on whether they underwent CR-TKA or MP-TKA. All patients were given general anesthesia and had the knee joint exposed in the supine position via a medial parapatellar approach. After ACL (anterior cruciate ligament) removal, PCL tension was evaluated. All patients in the CR group received a CR prosthesis (CR, Aikang, China), with all posterior cruciate ligaments retained and patellae resurfaced. All patients in the MP group received an MP prosthesis (Evolution Medial-Pivot Knee System, Micro Port Orthopedics, Arlington, TN, USA), and PCLs were also retained. All TKAs in both groups were performed by the senior author using conventional instruments according to a restricted kinematic alignment surgical technique, measured resection, intramedullary femoral localization, extramedullary tibial localization, and posterior referencing without computer-assisted orthopedic surgery. The surgeon in this study had more than 3000 TKAs experience and performed more than 300 knee replacements annually, and had at least 1 year of experience with both implant designs. In all cases, a tourniquet was inflated to 250 mm Hg prior to skin incision and deflated after the final components were cemented. The femoral component is aligned along the patient’s unique condylar axis by taking into account where cartilage has been lost and aligning jigs appropriately, and then performing a corresponding tibial resection to achieve gap balancing. The femur was positioned in neutral rotation with respect to the posterior condyles, adjusting for cartilage loss and, when present, bone loss. The posterior tibial slope and proximal tibial varus were individually matched, accounting for cartilage and bone loss, attempting to recreate each patient’s unique pre-arthritic joint line. Ligament releases during the initial exposure were performed only in the presence of a significant valgus-flexion deformity. According to the KA criteria, “femur first” bone resection was performed, followed by a tibial resection. A calibrated manual instrumentation was adopted in all cases. Any LDFA or MPTA exceeding 5° will be controlled within 5°. The overall hip-knee-ankle angle should be maintained within ± 3° of the neutral.[ 14 – 16 ] Regardless of the prosthesis and implant used, all patients underwent identical preoperative work-up through a dedicated perioperative medicine clinic and identical perioperative care to include multi-model pain management, perioperative antibiotics, physical therapy with day-of-surgery mobilization, and venous thromboembolism mechanical and chemical prophylaxis. All patients underwent standardized preoperative preparations and rehabilitation processes. All the patients received ice compress treatment after the operation. The patient received the guidance of a professional rehabilitation therapist from the second day after the operation including ankle pumping exercise and continuous passive machine exercises. During the six weeks following the surgery, various rehabilitation exercises such as self-assisted leg elevation and flexion-extension of the knee were carried out. A multimodal analgesic system, which involves the use of opioid painkillers combined with intravenous administration of parecoxib, was employed for the majority of patients. Unless the patient has a clear history of drug allergy. In order to prevent venous thromboembolism, a low-molecular-weight heparin-type anticoagulant was given. Clinical and radiographic evaluation Patients were assessed preoperatively and at 12 months postoperatively. When the medial and lateral condyles at the posterior part of the prosthesis are completely overlap, it was defined as a truly accurate lateral X-ray image, which is taken before the operation and on the third day after the operation. Clinical assessments included Forgotten Joint Score, physical examination with assessment of the active ROM of the knee, surgical data, and recording of adverse events, including infections, deep vein thrombosis/pulmonary embolism, stiffness ( 10 FFD), persisting pain, and unplanned revision surgery were recorded. The autonomous ROM of all patients’ knee was measured by the same experienced orthopedic surgeon, who was blinded to the patient’s treatment groups. All radiographic measurements were performed on standardized weight-bearing anteroposterior (AP) of long-leg X-rays and lateral knee radiographs taken preoperatively and postoperatively. The following parameters were assessed: Hip-Knee-Angle (HKA): Medial angle between the femoral mechanical axis and the tibial mechanical axis. Lateral Distal Femoral Angle (LDFA): Lateral angle subtended by the femoral mechanical axis and a line drawn across the distal femoral articular surface. Medial Proximal Tibial Angle (MPTA): Medial angle subtended by the tibial mechanical axis and a line drawn across the tibial articular surface at the most distal points. Lateral Femoral Component Angle (LFCA): The angle formed by the tangent line of the osteotomy plane of the anterior femoral condyle in the sagittal plane and the anterior femoral cortex in the sagittal plane. Lateral Tibial Component Angle (LTCA): The angle formed by the osteotomy plane of the tibia and the posterior tibial cortical line in front of the tibia. patella length: The distance between the tangent line of the superior edge of the patella and the inferior edge of the patella. Posterior condylar offset (PCO): Measured on true lateral radiographs as the maximum thickness of the posterior condylar projected posteriorly to the tangent of the posterior cortex of the femoral shaft. Coronal femoral width (LFW): LFW is the lateral femoral width, defined as the distance from the lateral condyle to the medial-lateral axis of the femur. PCO ratio: The PCO ratio is determined by dividing the PCO by the sum of the PCO and lateral femoral width. posterior tibial slope (PTS): The angle between the vertical line of the anterior cortical tangent and the tibial plateau line was the PTS. All measurements were conducted independently by two blinded radiologists to minimize bias. The measurement techniques are presented in Fig. 2 and Fig. 3 . Figure 3 -D Fig. 3 -E Fig. 3 -F Figure 3 Depictions of sagittal parameters radiographic measurements. Figure 3 -A The Lateral Femoral Condyle Angle (LFCA). Figure 3 -B The Lateral Tibial Condyle Angle (LTCA). Figure 3 -C The patella thickness. Figure 3 -D The patella length. Figure 3 -E The posterior femoral condylar offset (PCO) and Coronal femoral width (LFW). Figure 3 -F The posterior tibial slope (PTS) To ensure measurement reliability, two independent observers performed all radiographic measurements. Inter-observer and intra-observer reliability were assessed using intraclass correlation coefficients (ICCs) with 95% confidence intervals (CIs). ICC values were interpreted as follows: 0.90 indicating excellent reliability. Statistical analysis Data were analyzed using SPSS (version 25, IBM, Armonk, NY, USA). Continuous data are summarized as mean ± standard deviation (SD) if normally distributed, comparisons between groups were made using the independent-samples t test. The median ± interquartile range (IQR) if not normally distributed, and the Mann–Whitney U test was used for analysis. Categorical data are summarized as rates and frequencies. The difference in the categorical outcomes between groups was assessed using the chi-square test. Statistical significance was set at < .05. Results The patient characteristics are shown in Table 1 . There were no significant differences in age, gender, height, weight, or operation side between the CR group and the MP group. The number of patients was 60 for the MP groups and 64 for the CR groups, respectively. Table 1 A Demographics and Pre-operation FJS of the two groups Demographics MP-TKA Mean ± SD(95%CI) CR-TKA Mean ± SD(95%CI) P value Age(years) 68.45 ± 8.44 68.92 ± 5.31 0.712 Height(cm) 161.63 ± 7.10 163.64 ± 7.02 0.116 Weight(Kg) 69.30 ± 11.29 69.93 ± 9.09 0.734 Sex 0.229 male 13 20 femal 47 44 Opreration side 0.595 right 29 34 left 31 30 Pre-operation FJS 25.15 ± 8.68 24.33 ± 8.74 0.601 The clinical and radiographic measurements are presented in Table 2 Table 3 . Pre-operatively, there were no significant differences between the two groups in terms of demographic data, HKA, LDFA, MPTA, sagittal plane parameters and post-operation FJS (p > 0.05). Table 2 Pre-opreation HKA, LDFA, MPTA, ROM and sagittal plane parameters of the two groups HKA MP-TKA Mean ± SD(95%CI) CR-TKA Mean ± SD(95%CI) P value 171.50 ± 5.18 172.78 ± 4.98 0.163 LDFA 89.78 ± 3.09 89.42 ± 3.50 0.544 MPTA 84.48 ± 3.02 85.28 ± 3.15 0.153 PCO (mm) 26.61 ± 3.58 27.13 ± 3.77 0.438 LFW (mm) 58.01 ± 5.69 56.20 ± 5.42 0.071 PCO ratio 0.47 ± 0.05 0.48 ± 0.05 0.128 PTS ROM 4.10 ± 1.20 98.33 ± 6.55 4.34 ± 1.25 97.34 ± 6.55 0.271 0.402 Patella thickness Patella length 17.52 ± 2.65 40.38 ± 5.27 18.09 ± 2.82 40.14 ± 5.41 0.243 0.243 Table 3 Post-opreation HKA, LDFA, MPTA, sagittal plane parameters, FJS and post-operation ROM of the two groups HKA MP-TKA Mean ± SD(95%CI) CR-TKA Mean ± SD(95%CI) P value 175.77 ± 2.08 176.27 ± 2.18 0.195 LDFA 90.29 ± 1.91 90.34 ± 1.69 0.880 MPTA 86.90 ± 2.53 86.82 ± 2.20 0.855 PCO (mm) 26.11 ± 4.08 27.65 ± 3.36 0.024 LFW (mm) 57.51 ± 5.03 56.72 ± 4.26 0.348 PCO ratio 0.45 ± 0.06 0.48 ± 0.05 0.001 Changes of PCO (mm) 2.42 ± 1.52 3.62 ± 2.11 <0.001 PTS 4.57 ± 1.06 4.41 ± 1.09 0.410 LFCA 9.53 ± 2.79 9.22 ± 2.78 0.313 LTCA 84.02 ± 5.53 83.52 ± 6.27 0.638 Patella thickness 15.08 ± 2.68 17.61 ± 15.33 0.210 Patella length 36.75 ± 4.39 37.16 ± 4.68 0.618 FJS ROM-3 days post-operation ROM-1year post-operation 40.70 ± 10.46 102.92 ± 7.93 103.35 ± 6.10 38.44 ± 9.54 97.34 ± 5.49 100.52 ± 4.97 0.210 <0.001 0.024 The MP group was more advantageous in changes of PCO (MP group changes of PCO: 2.42 ± 1.52 mm vs CR group changes of PCO: 3.62 ± 2.11 mm p < 0.001), the post-operation PCO and PCO ratio was significantly less in the MP group (MP group PCO: 26.11 ± 4.08mm vs CR group PCO: 27.65 ± 3.36mm p = 0.024; MP group PCO ratio: 0.45 ± 0.06 vs CR group PCO ratio: 0.48 ± 0.05 p = 0.001), there were no significant differences between the two groups in terms of others sagittal plane parameters (p > 0.05). The post-operative ROM was significantly better in the MP group in 3-days post-operation and the 12-months post-operation (3-days post-operation in MP group:102.92°±7.93 vs 3-days post-operation in CR group:97.34°±5.49 p < 0.001, 12-months post-operation in MP group:103.35 ± 6.10 vs 12-months post-operation in CR group: 100.52 ± 4.97 p = 0.024) . There was no intraoperative complication in both groups. One case in the CR group had wound exudation, which healed after a pressure dressing. Discussion The most important finding of this study is that patients who performed MP-TKA achieved a better sagittal plane balance after the operation. There was significant difference in PCO, PCO ratio between the MP-TKA and the CR-TKA after surgery. The 3 days and 12 months post-operative ROM after MP-TKA was better than CR-TKA. However, these improvements of the ROM did not bring a superiority postoperative PROMs. The reason why MP-TKA achieves better PCO restoration may be related to the design of the polyethylene liner. During the MP-TKA operation procedure, there is no need to maintain femur rollback by the PCL benefit by the constrained bearing surface. Therefore, it is unnecessary to additionally increase the PCO to maintain the PCL tension during the operation. Millions of patients undergo TKA every year. However, 20% of patients remain dissatisfied with their outcomes. It is generally accepted that total hip recovery is easier and quicker than TKA. Numerous prior studies have pointed out that CR and PS TKA fail to reproduce native knee kinematics reliably. The failure of traditional TKA designs to reproduce physiologic knee kinematics may contribute to patient dissatisfaction.[ 17 , 18 ] The MP design, mimics a natural knee joint and reproduces natural knee biomechanics with medial stability and lateral mobility.[ 19 , 20 ] Not only does this improve knee kinematics, but it also restores joint stability, knee flexion, and reduces wear on the polyethylene liner. The MP designs have reported better postoperative ROM and mid-term follow-up outcomes compared with PS-TKA.[ 21 ] Hideki et al has shown that MP-TKA had a higher survival rate and better patient awareness of the prosthetic joint over 10 years follow-up.[ 22 ] In this study, MP-TKA also demonstrated excellent clinical outcomes, which were similar to the results of previous studies, indicating the reliability of MP-TKA. In recent years, an increasing number of studies have begun to recognize the importance of sagittal plane positioning of the prosthesis after TKA. Bellemans et al discovered that a small PCO would cause the collision between the femoral shaft and the posterior part of the tibial plateau when the knee joint was flexed, limiting the flexion range of the knee. [ 13 ] Soda et al proposed the Posterior Condylar Offset Ratio (PCOR) in order to eliminate the influence of the size of femoral component on individual differences. [ 23 ] Onodera et al believed that excess PCO after operation may cause relative shortening of the posterior soft tissue, which might cause flexion contracture of the knee. [ 24 ] Costanzo et al reported that changes in postoperative PCO would cause patellar clunk syndrome. [ 25 ] Two recent studies have highlighted the importance in PCO restoration after revision TKA with improved outcome.[ 12 , 26 ] Few studies have compared the PCO and clinical outcomes between different prostheses design. A finite element study shown that PCO changs magnitude influenced postoperative kinematics, especially for CR-TKA.[ 27 ] To our knowledge, this study is the only one that compared the postoperative PCO of MP-TKA and CR-TKA in X-ray photographs. In our study, all TKA retained the PCL, which enhances the comparability between the two groups. In this study, MP-TKA demonstrated potential advantages in restoring PCO. Femur intramedullary localization and tibial extramedullary localization were used for all TKAs in this study. Femur intramedullary localization refers to the placing of the osteotomy guide mold in the femur medullary cavity. It is simple and easy to implement, so it has become the preferred positioning method for most orthopedic surgeons. The premise is that the long axis of the medullary cavity coincides with the anatomical axis of the femur on the coronal and sagittal planes. The intramedullary localization offers the advantage of a positioning process that is not susceptible to external interference. Comparing with intramedullary positioning, extramedullary tibial localization has fewer complications. With some surface bone markers, it can meet the requirements of determining the alignment of the lower limbs. To our knowledge, it has depended to a certain extent on the operator’s visual judgment and empirical operation to determine tibial osteotomy. Before tibial osteotomy, the positioning of the tibial extramedullary locator is essential. The tibial extramedullary guide should be parallel to the long axis of the tibia on the coronal and sagittal planes. However, the placement of the prosthesis after tibial osteotomy still has some deviation, due to the physiological curvature of the tibia.[ 28 ] In this study, both MP-TKA and CR-TKA demonstrated clinically acceptable PCO, PTS and FJS. Long-term follow-up will still be necessary in the future. A good ROM is essential for daily life. When walking, the knee joint needs to be flexed at 60–70 degrees. When going up or down stairs, the knee joint needs to be flexed at 90–120 degrees. In Asia, patients may require an increased ROM to participate in religious activities, such as cross-legged sitting and kneeling.[ 29 ] Although a better ROM is theoretically more beneficial for the patient in their daily life, excessive postoperative ROM will increase patellofemoral pressure, which may result in anterior knee pain, excessive wear of the polyethylene liner, fracture of the patellar, and other complications.[ 30 , 31 ] Therefore, surgeons should consider comprehensive when performing the osteotomy to keep the PTS in a suitable range for normal individuals and to restore normal knee kinematics as much as possible. In our study, both groups of patients underwent the same surgical technique. The ROM in the MP-TKA group significantly improved, and there was no significant increase in complications. This is similar to the results of previous studies, demonstrating the superiority of MP.[ 32 ] A better ROM might be related to the accurate restoration of the PCO and the re-establishment of balance in the knee. Some studies have noted that in TKA surgery guided by the MA philosophy, changes in femoral rotation during postoperative lateral X-rays can result in medial and lateral posterior condyles that overlap entirely, rendering the image not a “true lateral knee radiograph”. Ignoring this discrepancy is misleading.[ 33 , 34 ] In our study, TKA guided by the restricted kinematic alignment (rKA) philosophy, femoral components are often placed in 0° rotation. “True lateral knee radiographs” are achieved in the postoperative radiograph, which reduces the misleading. The main strengths of this study were that clinical outcomes were recorded by blinded observers using standardized techniques with high observer agreement on all outcomes. Compared with the CR group, the MP group showed a better ROM in 3 days and 12 months post-operative. However, no significant difference was observed in FJS, which might be related to the ceiling effect of FJS.[ 35 , 36 ] There are several limitations in the literature involving the retrospective design of the study; the relatively small sample size is a notable limitation, patients were not randomized between the treatment group, selection bias is a relevant limitation. In addition, the patients who were operated by the same surgical team; however, this limits the generalizability of the findings. More generalizable results could be achieved through prospective, randomized controlled studies with larger sample sizes. Conclusion The MP design TKA achieves better sagittal plane balance compared with the CR design TKA. The reason may be related that it is unnecessary to additionally increase the PCO to maintain the PCL tension during the MP operation. Declarations Ethics approval: The Institution’s Review Board of Peking Union Medical College Hospital gave ethical approval (Approval Number: K9408) for our retrospective study on November 05, 2025. All procedures were conducted in compliance with the guidelines of the Declaration of Helsinki. Informed consent: Informed consent was obtained from all individual participants included in the study. Clinical trial number Not applicable Consent for publication: Not applicable. Competing interests: The authors declare no conflict of interest. Funding: This study was partially funded by the Natural Science Foundation of Beijing Municipality (Grant No. L252157). Author Contribution Mingyang Ma drafted the manuscript. Sen Liu, Hongjun Xu and Yang Yu performed the data collection and data analysis. Zhongyin Ji and Guiguan Wang performed the data interpretation. 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J Am Acad Orthop Surg 27(17):642–651. 10.5435/jaaos-d-18-00347 Scott DF, Hellie AA (2023) Mid-Flexion, Anteroposterior Stability of Total Knee Replacement Implanted with Kinematic Alignment: A Randomized, Quantitative Radiographic Laxity Study with Posterior-Stabilized and Medial-Stabilized Implants. J Bone Joint Surg Am 105(1):9–19. 10.2106/jbjs.22.00549 Shu L, Yamamoto K, Kai S, Inagaki J, Sugita N (2019) Symmetrical cruciate-retaining versus medial pivot prostheses: The effect of intercondylar sagittal conformity on knee kinematics and contact mechanics. Comput Biol Med 108:101–110. 10.1016/j.compbiomed.2019.03.005 Kulshrestha V, Sood M, Kanade S, Kumar S, Datta B, Mittal G (2020) Early Outcomes of Medial Pivot Total Knee Arthroplasty Compared to Posterior-Stabilized Design: A Randomized Controlled Trial. Clin Orthop Surg 12(2):178–186. 10.4055/cios19141 Ueyama H, Kanemoto N, Minoda Y, Yamamoto N, Taniguchi Y, Nakamura H (2022) No Difference in Postoperative Knee Flexion and Patient Joint Awareness Between Cruciate-Substituting and Cruciate-Retaining Medial Pivot Total Knee Prostheses: A 10-Year Follow-Up Study. J Arthroplast 37(2):279–285. 10.1016/j.arth.2021.11.016 Soda Y, Oishi J, Nakasa T, Nishikawa K, Ochi M (2007) New parameter of flexion after posterior stabilized total knee arthroplasty: posterior condylar offset ratio on X-ray photographs. Arch Orthop Trauma Surg 127(3):167–170. 10.1007/s00402-007-0295-x Onodera T, Majima T, Nishiike O, Kasahara Y, Takahashi D (2013) Posterior femoral condylar offset after total knee replacement in the risk of knee flexion contracture. J Arthroplast 28(7):1112–1116. 10.1016/j.arth.2012.07.029 Costanzo JA, Aynardi MC, Peters JD, Kopolovich DM, Purtill JJ (2014) Patellar clunk syndrome after total knee arthroplasty; risk factors and functional outcomes of arthroscopic treatment. J Arthroplast 29(9 Suppl):201–204. 10.1016/j.arth.2014.03.045 Elbardesy H, McLeod A, Gul R, Harty J (2021) The role of joint line position and restoration of posterior condylar offset in revision total knee arthroplasty: a systematic review of 422 revision knees arthroplasty. Acta Orthop Belg 87(3):453–460 Kang KT, Kwon SK, Kwon OR, Lee JS, Koh YG (2019) Comparison of the biomechanical effect of posterior condylar offset and kinematics between posterior cruciate-retaining and posterior-stabilized total knee arthroplasty. Knee 26(1):250–257. 10.1016/j.knee.2018.11.017 Ostermeier S, Hurschler C, Windhagen H, Stukenborg-Colsman C (2006) In vitro investigation of the influence of tibial slope on quadriceps extension force after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc 14(10):934–939. 10.1007/s00167-006-0078-x Li C, Zeng Y, Shen B, Yang J, Zhou Z, Kang P, Pei F (2015) Patients achieved greater range of movement when using high-flexion implants. Knee Surg Sports Traumatol Arthrosc 23(6):1598–1609. 10.1007/s00167-014-3314-9 Kim YH, Park JW, Kim JS (2012) High-flexion total knee arthroplasty: survivorship and prevalence of osteolysis: results after a minimum of ten years of follow-up. J Bone Joint Surg Am 94(15):1378–1384. 10.2106/jbjs.K.01229 Bollars P, Luyckx JP, Innocenti B, Labey L, Victor J, Bellemans J (2011) Femoral component loosening in high-flexion total knee replacement: an in vitro comparison of high-flexion versus conventional designs. J Bone Joint Surg Br 93(10):1355–1361. 10.1302/0301-620x.93b10.25436 Nakamura J, Inoue T, Suguro T, Suzuki M, Sasho T, Hagiwara S, Akagi R, Orita S, Inage K, Akazawa T, Ohtori S (2018) A comparative study of flat surface design and medial pivot design in posterior cruciate-retaining total knee arthroplasty: a matched pair cohort study of two years. BMC Musculoskelet Disord 19(1):234. 10.1186/s12891-018-2138-z Weinberg DS, Streit JJ, Gebhart JJ, Williamson DF, Goldberg VM (2015) Important Differences Exist in Posterior Condylar Offsets in an Osteological Collection of 1,058 Femurs. J Arthroplast 30(8):1434–1438. 10.1016/j.arth.2015.02.027 Koh YG, Nam JH, Chung HS, Kim HJ, Chun HJ, Kang KT (2019) Gender differences in morphology exist in posterior condylar offsets of the knee in Korean population. Knee Surg Sports Traumatol Arthrosc 27(5):1628–1634. 10.1007/s00167-018-5259-x Eckhard L, Munir S, Wood D, Talbot S, Brighton R, Walter B, Baré J (2021) The ceiling effects of patient reported outcome measures for total knee arthroplasty. Orthop Traumatol Surg Res 107(3):102758. 10.1016/j.otsr.2020.102758 Ho KK, Chau WW, Lau LC, Ong MT (2022) Traditional Chinese-Hong Kong version of Forgotten Joint Score-12 (FJS-12) for patients with osteoarthritis of the knee underwent joint replacement surgery: cross-cultural and sub-cultural adaptation, and validation. BMC Musculoskelet Disord 23(1):222. 10.1186/s12891-022-05156-5 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. 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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-9201898","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":615483724,"identity":"2b178363-d825-4a23-9ef3-1425d4cb796e","order_by":0,"name":"Mingyang Ma","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Mingyang","middleName":"","lastName":"Ma","suffix":""},{"id":615483727,"identity":"530d0021-df50-4a88-9533-98dbe410949c","order_by":1,"name":"Sen Liu","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Sen","middleName":"","lastName":"Liu","suffix":""},{"id":615483729,"identity":"ad8d166a-e70c-4528-bc11-da899c3901e3","order_by":2,"name":"Yang Yu","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Yang","middleName":"","lastName":"Yu","suffix":""},{"id":615483732,"identity":"f9b22fff-0a68-45e7-8fe9-e19e917cd566","order_by":3,"name":"Zhongyin Ji","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Zhongyin","middleName":"","lastName":"Ji","suffix":""},{"id":615483733,"identity":"6f799dab-d673-406c-8f8b-253cdba210c7","order_by":4,"name":"Hongjun Xu","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Hongjun","middleName":"","lastName":"Xu","suffix":""},{"id":615483734,"identity":"52dd8564-79ca-4e22-861c-680fa09a28fc","order_by":5,"name":"Guiguan Wang","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Guiguan","middleName":"","lastName":"Wang","suffix":""},{"id":615483736,"identity":"a32e7485-ec04-41aa-b469-c9f13b5d90a8","order_by":6,"name":"Zhaojing Yin","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Zhaojing","middleName":"","lastName":"Yin","suffix":""},{"id":615483740,"identity":"11b9d6ac-91e0-456c-b658-dc4fc2e3f930","order_by":7,"name":"Yiyang Du","email":"","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":false,"prefix":"","firstName":"Yiyang","middleName":"","lastName":"Du","suffix":""},{"id":615483742,"identity":"f9962e96-b0a8-47bf-b44b-9ddfdf33599d","order_by":8,"name":"Wenwei Qian","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxUlEQVRIiWNgGAWjYDACZjApwWN/vLHx4QcStNjIMZw53GwsQYJdacYMN9LbBHiIUct3nPnZY962w4mNMx+2MUgw2MnpNhDQInmYzdwYpKVZOrHtQQFDsrHZAQJaDA4zmEnnbjuc2Cad2G4gwXAgcRthLezfwFp6JA+2SfAQp4UHZEuasYQEI5FaJA/zlEn//WcjZ8CTCAxkAyL8wnf++DbJGWckeAzYjz98+KHCTo6gFgZUBQaElGNqGQWjYBSMglGABQAA0ehCFwbSbAwAAAAASUVORK5CYII=","orcid":"","institution":"Chinese Academy of Medical Sciences and Peking Union Medical College","correspondingAuthor":true,"prefix":"","firstName":"Wenwei","middleName":"","lastName":"Qian","suffix":""}],"badges":[],"createdAt":"2026-03-23 14:38:40","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9201898/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9201898/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105984205,"identity":"b151e856-2f0f-497a-a558-d81499ab047c","added_by":"auto","created_at":"2026-04-02 07:13:29","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":61841,"visible":true,"origin":"","legend":"\u003cp\u003eThe flowchart shows the total number of TKAs performed during the study period and the numbers of TKAs performed in both groups.\u003c/p\u003e","description":"","filename":"1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9201898/v1/3962cf89ecc00f2eab56d7b9.jpg"},{"id":105984204,"identity":"e8db836e-3942-4100-b2e6-7841dc32d800","added_by":"auto","created_at":"2026-04-02 07:13:29","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":70607,"visible":true,"origin":"","legend":"\u003cp\u003eDepictions of radiographic measurements. Fig. 2-A The hip knee-ankle angle (HKA), femoral mechanical axis (FMA), and tibial mechanical axis (TMA). Fig. 2-B The lateral distal femoral angle (LDFA), medial proximal tibial angle (MPTA)\u003c/p\u003e","description":"","filename":"2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9201898/v1/0b22628514f072d7f7cd566a.jpg"},{"id":105984209,"identity":"77bc5baa-3734-4d95-8249-0b4ff60c12c7","added_by":"auto","created_at":"2026-04-02 07:13:31","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":107466,"visible":true,"origin":"","legend":"\u003cp\u003eDepictions of sagittal parameters radiographic measurements. Fig.3-A The Lateral Femoral Condyle Angle (LFCA). Fig.3-B The Lateral Tibial Condyle Angle (LTCA). Fig.3-C The patella thickness. Fig.3-D The patella length. Fig.3-E The posterior femoral condylar offset (PCO) and Coronal femoral width (LFW). Fig.3-F The posterior tibial slope (PTS)\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9201898/v1/d4c72c07e5b637facceaec82.jpg"},{"id":107340193,"identity":"cac2b07d-9cec-4167-9a5e-643c5db04a54","added_by":"auto","created_at":"2026-04-20 14:13:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":631343,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9201898/v1/6fb663b9-be6d-4e94-a689-9a493ba73d9f.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"The Medial Pivot design achieves better sagittal plane balance in the restricted kinematic alignment total knee arthroplasty","fulltext":[{"header":"Introduction","content":"\u003cp\u003eTotal knee arthroplasty (TKA) is an effective treatment for alleviating the pain and improving the function of the patient's knee of the end-stage knee joint diseases. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] The design of knee prosthesis has undergone remarkable revision and improvement since 1950, with new implant designs and refinement of surgical techniques leading to improvements in clinical outcomes. However, patient satisfaction rate after TKA is far from surgeons\u0026rsquo; and patients\u0026rsquo; expectations of the perfect operation, 20% of patients remain dissatisfied with their outcomes.[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] Various implant prosthesis designs, including posterior-stabilized (PS), cruciate-retaining (CR), cruciate-substitute (CS), medial-pivot (MP), and bilateral cruciate ligament preservation, have been proposed to match knees with different characteristics.[\u003cspan additionalcitationids=\"CR4 CR5\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] Although several of TKA implant designs are widely used, the ideal TKA design has not been definitively put across in the literature. There is renewed surgeons' interesting in evaluating implant designs for potential improvement in biomechanics of the knee after surgery.\u003c/p\u003e \u003cp\u003eThe classical CR design with the assumption that preserving the native posterior cruciate ligament (PCL) is advantageous in keeping knee joint proprioception, reproducing physiologic knee biomechanics, and maintaining femoral rollback. However, irregular kinematics, abnormal patellar tracking, accelerated polyethylene wear, and poor range of motion (ROM) have all been reported, which compromising patient satisfaction rate.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] Since 1990s, the MP design has been in clinical. Kinematic research demonstrated that the natural knee functioned like a \u0026ldquo;ball and socket\u0026rdquo; joint, with the lateral femoral condyle translated in an anteroposterior direction and rotating around the medial compartment inflection. The MP is designed to replicate the biomechanics of the natural knee accurately, providing greater stability and maintaining knee flexibility. Several studies have reported favorable clinical and functional mid-term outcomes of MP knees.[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] However, reasons for consistently high rates of patient satisfaction following an MP-TKA remain poor understand.\u003c/p\u003e \u003cp\u003eSeveral studies have reported that restoration of posterior femoral condylar offset (PCO) is important to achieve sagittal plane balance, providing mid-flexion stability and potentially increasing the post-operation ROM. One previous studies have shown that both an increase and a decrease in PCO will lead to mid-flexion instability, restoration of the posterior offset within a range of 2 mm is necessary to avoid mid-flexion instability.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] Clement et al. has shown that PCO restoration correlates with improved functional outcomes after revision TKA.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e] Bellemans et al. demonstrated that restoring the PCO during TKA maximizes postoperative ROM and prevents posterior impingement.[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] Restoration of PCO is recommended in TKA.\u003c/p\u003e \u003cp\u003eTo the best of our knowledge, studies on sagittal plane parameters and ROM comparing CR and MP prosthesis are lacking. The purpose of this study was to compare the sagittal plane parameters, ROM, and patient-reported outcome measures (PROMs) between the Cruciate Retaining TKA and the Medial Pivot TKA.\u003c/p\u003e"},{"header":"Patients and methods","content":"\u003cp\u003eInclusion and exclusion criteria\u003c/p\u003e \u003cp\u003e This retrospective, single-center study was approved by the Ethics Committee of Peking Union Medical College Hospital (Approval Number: K9408), and informed consent was obtained from all participants before their inclusion in this study. All the benefits and risks of performing MP-TKA and CR-TKA are explained to patients preoperatively so they can decide which surgical procedure to perform. We analyzed patients who underwent TKA by the same operation group at the Department of Orthopedics, Peking Union Medical College Hospital, between February 2024 and January 2025. The total number of TKAs performed during the study period and the numbers of TKAs performed in both groups were showed in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eA total of 124 patients with knee osteoarthritis (OA) were included based on the following inclusion criteria: (1) diagnosis with primary knee OA and requiring TKA, (2) age between 50 and 85 years, and (3) with complete clinical records and radiographic data. The exclusion criteria were as follows: (1) complex primary or revision TKA, (2) inability to visualize anatomic landmarks on radiographs, (3) previous surgical history or infection history of the knee joint on the operation side; (4) the knee joint on the surgical side has suffered joint dysfunction due to factors such as nerves, muscles, psychological issues, or systemic diseases like immunity disorders.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSurgical techniques\u003c/p\u003e \u003cp\u003eAll patients included in the study were categorized into the CR group and MP group depending on whether they underwent CR-TKA or MP-TKA. All patients were given general anesthesia and had the knee joint exposed in the supine position via a medial parapatellar approach. After ACL (anterior cruciate ligament) removal, PCL tension was evaluated. All patients in the CR group received a CR prosthesis (CR, Aikang, China), with all posterior cruciate ligaments retained and patellae resurfaced. All patients in the MP group received an MP prosthesis (Evolution Medial-Pivot Knee System, Micro Port Orthopedics, Arlington, TN, USA), and PCLs were also retained. All TKAs in both groups were performed by the senior author using conventional instruments according to a restricted kinematic alignment surgical technique, measured resection, intramedullary femoral localization, extramedullary tibial localization, and posterior referencing without computer-assisted orthopedic surgery. The surgeon in this study had more than 3000 TKAs experience and performed more than 300 knee replacements annually, and had at least 1 year of experience with both implant designs. In all cases, a tourniquet was inflated to 250 mm Hg prior to skin incision and deflated after the final components were cemented. The femoral component is aligned along the patient\u0026rsquo;s unique condylar axis by taking into account where cartilage has been lost and aligning jigs appropriately, and then performing a corresponding tibial resection to achieve gap balancing. The femur was positioned in neutral rotation with respect to the posterior condyles, adjusting for cartilage loss and, when present, bone loss. The posterior tibial slope and proximal tibial varus were individually matched, accounting for cartilage and bone loss, attempting to recreate each patient\u0026rsquo;s unique pre-arthritic joint line. Ligament releases during the initial exposure were performed only in the presence of a significant valgus-flexion deformity. According to the KA criteria, \u0026ldquo;femur first\u0026rdquo; bone resection was performed, followed by a tibial resection. A calibrated manual instrumentation was adopted in all cases. Any LDFA or MPTA exceeding 5\u0026deg; will be controlled within 5\u0026deg;. The overall hip-knee-ankle angle should be maintained within \u0026plusmn;\u0026thinsp;3\u0026deg; of the neutral.[\u003cspan additionalcitationids=\"CR15\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eRegardless of the prosthesis and implant used, all patients underwent identical preoperative work-up through a dedicated perioperative medicine clinic and identical perioperative care to include multi-model pain management, perioperative antibiotics, physical therapy with day-of-surgery mobilization, and venous thromboembolism mechanical and chemical prophylaxis. All patients underwent standardized preoperative preparations and rehabilitation processes. All the patients received ice compress treatment after the operation. The patient received the guidance of a professional rehabilitation therapist from the second day after the operation including ankle pumping exercise and continuous passive machine exercises. During the six weeks following the surgery, various rehabilitation exercises such as self-assisted leg elevation and flexion-extension of the knee were carried out. A multimodal analgesic system, which involves the use of opioid painkillers combined with intravenous administration of parecoxib, was employed for the majority of patients. Unless the patient has a clear history of drug allergy. In order to prevent venous thromboembolism, a low-molecular-weight heparin-type anticoagulant was given.\u003c/p\u003e \u003cp\u003eClinical and radiographic evaluation\u003c/p\u003e \u003cp\u003ePatients were assessed preoperatively and at 12 months postoperatively. When the medial and lateral condyles at the posterior part of the prosthesis are completely overlap, it was defined as a truly accurate lateral X-ray image, which is taken before the operation and on the third day after the operation. Clinical assessments included Forgotten Joint Score, physical examination with assessment of the active ROM of the knee, surgical data, and recording of adverse events, including infections, deep vein thrombosis/pulmonary embolism, stiffness (\u0026lt;\u0026thinsp;90 flexion, or \u0026gt;\u0026thinsp;10 FFD), persisting pain, and unplanned revision surgery were recorded. The autonomous ROM of all patients\u0026rsquo; knee was measured by the same experienced orthopedic surgeon, who was blinded to the patient\u0026rsquo;s treatment groups.\u003c/p\u003e \u003cp\u003eAll radiographic measurements were performed on standardized weight-bearing anteroposterior (AP) of long-leg X-rays and lateral knee radiographs taken preoperatively and postoperatively. The following parameters were assessed:\u003c/p\u003e \u003cp\u003eHip-Knee-Angle (HKA): Medial angle between the femoral mechanical axis and the tibial mechanical axis.\u003c/p\u003e \u003cp\u003eLateral Distal Femoral Angle (LDFA): Lateral angle subtended by the femoral mechanical axis and a line drawn across the distal femoral articular surface.\u003c/p\u003e \u003cp\u003eMedial Proximal Tibial Angle (MPTA): Medial angle subtended by the tibial mechanical axis and a line drawn across the tibial articular surface at the most distal points.\u003c/p\u003e \u003cp\u003eLateral Femoral Component Angle (LFCA): The angle formed by the tangent line of the osteotomy plane of the anterior femoral condyle in the sagittal plane and the anterior femoral cortex in the sagittal plane.\u003c/p\u003e \u003cp\u003eLateral Tibial Component Angle (LTCA): The angle formed by the osteotomy plane of the tibia and the posterior tibial cortical line in front of the tibia.\u003c/p\u003e \u003cp\u003epatella length: The distance between the tangent line of the superior edge of the patella and the inferior edge of the patella.\u003c/p\u003e \u003cp\u003ePosterior condylar offset (PCO): Measured on true lateral radiographs as the maximum thickness of the posterior condylar projected posteriorly to the tangent of the posterior cortex of the femoral shaft.\u003c/p\u003e \u003cp\u003eCoronal femoral width (LFW): LFW is the lateral femoral width, defined as the distance from the lateral condyle to the medial-lateral axis of the femur.\u003c/p\u003e \u003cp\u003ePCO ratio: The PCO ratio is determined by dividing the PCO by the sum of the PCO and lateral femoral width.\u003c/p\u003e \u003cp\u003eposterior tibial slope (PTS): The angle between the vertical line of the anterior cortical tangent and the tibial plateau line was the PTS.\u003c/p\u003e \u003cp\u003eAll measurements were conducted independently by two blinded radiologists to minimize bias. The measurement techniques are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e2\u003c/span\u003e and Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-D Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-E Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-F\u003c/p\u003e \u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e Depictions of sagittal parameters radiographic measurements. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-A The Lateral Femoral Condyle Angle (LFCA). Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-B The Lateral Tibial Condyle Angle (LTCA). Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-C The patella thickness. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-D The patella length. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-E The posterior femoral condylar offset (PCO) and Coronal femoral width (LFW). Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e3\u003c/span\u003e-F The posterior tibial slope (PTS)\u003c/p\u003e \u003cp\u003eTo ensure measurement reliability, two independent observers performed all radiographic measurements. Inter-observer and intra-observer reliability were assessed using intraclass correlation coefficients (ICCs) with 95% confidence intervals (CIs). ICC values were interpreted as follows: \u0026lt; 0.50 indicating poor reliability, 0.50\u0026ndash;0.75 indicating moderate reliability, 0.75\u0026ndash;0.90 indicating good reliability, and \u0026gt;\u0026thinsp;0.90 indicating excellent reliability.\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eData were analyzed using SPSS (version 25, IBM, Armonk, NY, USA). Continuous data are summarized as mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD) if normally distributed, comparisons between groups were made using the independent-samples t test. The median\u0026thinsp;\u0026plusmn;\u0026thinsp;interquartile range (IQR) if not normally distributed, and the Mann\u0026ndash;Whitney U test was used for analysis. Categorical data are summarized as rates and frequencies. The difference in the categorical outcomes between groups was assessed using the chi-square test. Statistical significance was set at \u0026lt;\u0026thinsp;.05.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eThe patient characteristics are shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. There were no significant differences in age, gender, height, weight, or operation side between the CR group and the MP group. The number of patients was 60 for the MP groups and 64 for the CR groups, respectively.\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\u003eA Demographics and Pre-operation FJS of the two groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDemographics\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMP-TKA\u003c/p\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(95%CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCR-TKA\u003c/p\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(95%CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\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\u003eAge(years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e68.45\u0026thinsp;\u0026plusmn;\u0026thinsp;8.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e68.92\u0026thinsp;\u0026plusmn;\u0026thinsp;5.31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.712\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\u003e161.63\u0026thinsp;\u0026plusmn;\u0026thinsp;7.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e163.64\u0026thinsp;\u0026plusmn;\u0026thinsp;7.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.116\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\u003e69.30\u0026thinsp;\u0026plusmn;\u0026thinsp;11.29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e69.93\u0026thinsp;\u0026plusmn;\u0026thinsp;9.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.734\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.229\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003emale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e13\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003efemal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOpreration side\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.595\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eright\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e29\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eleft\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePre-operation FJS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e25.15\u0026thinsp;\u0026plusmn;\u0026thinsp;8.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.33\u0026thinsp;\u0026plusmn;\u0026thinsp;8.74\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.601\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe clinical and radiographic measurements are presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e.\u003c/p\u003e \u003cp\u003ePre-operatively, there were no significant differences between the two groups in terms of demographic data, HKA, LDFA, MPTA, sagittal plane parameters and post-operation FJS (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05).\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\u003ePre-opreation HKA, LDFA, MPTA, ROM and sagittal plane parameters of the two groups\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=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" 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\u003eHKA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMP-TKA\u003c/p\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(95%CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCR-TKA\u003c/p\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(95%CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e171.50\u0026thinsp;\u0026plusmn;\u0026thinsp;5.18\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e172.78\u0026thinsp;\u0026plusmn;\u0026thinsp;4.98\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.163\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e89.78\u0026thinsp;\u0026plusmn;\u0026thinsp;3.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e89.42\u0026thinsp;\u0026plusmn;\u0026thinsp;3.50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.544\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMPTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e84.48\u0026thinsp;\u0026plusmn;\u0026thinsp;3.02\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e85.28\u0026thinsp;\u0026plusmn;\u0026thinsp;3.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.153\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePCO (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.61\u0026thinsp;\u0026plusmn;\u0026thinsp;3.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e27.13\u0026thinsp;\u0026plusmn;\u0026thinsp;3.77\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.438\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLFW (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e58.01\u0026thinsp;\u0026plusmn;\u0026thinsp;5.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e56.20\u0026thinsp;\u0026plusmn;\u0026thinsp;5.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.071\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePCO ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.47\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.128\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePTS\u003c/p\u003e \u003cp\u003eROM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.10\u0026thinsp;\u0026plusmn;\u0026thinsp;1.20\u003c/p\u003e \u003cp\u003e98.33\u0026thinsp;\u0026plusmn;\u0026thinsp;6.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.34\u0026thinsp;\u0026plusmn;\u0026thinsp;1.25\u003c/p\u003e \u003cp\u003e97.34\u0026thinsp;\u0026plusmn;\u0026thinsp;6.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.271\u003c/p\u003e \u003cp\u003e0.402\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePatella thickness\u003c/p\u003e \u003cp\u003ePatella length\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e17.52\u0026thinsp;\u0026plusmn;\u0026thinsp;2.65\u003c/p\u003e \u003cp\u003e40.38\u0026thinsp;\u0026plusmn;\u0026thinsp;5.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e18.09\u0026thinsp;\u0026plusmn;\u0026thinsp;2.82\u003c/p\u003e \u003cp\u003e40.14\u0026thinsp;\u0026plusmn;\u0026thinsp;5.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.243\u003c/p\u003e \u003cp\u003e0.243\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\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\u003ePost-opreation HKA, LDFA, MPTA, sagittal plane parameters, FJS and post-operation ROM of the two groups\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=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" 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\u003eHKA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMP-TKA\u003c/p\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(95%CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCR-TKA\u003c/p\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD(95%CI)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e175.77\u0026thinsp;\u0026plusmn;\u0026thinsp;2.08\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e176.27\u0026thinsp;\u0026plusmn;\u0026thinsp;2.18\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.195\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLDFA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e90.29\u0026thinsp;\u0026plusmn;\u0026thinsp;1.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e90.34\u0026thinsp;\u0026plusmn;\u0026thinsp;1.69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.880\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMPTA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e86.90\u0026thinsp;\u0026plusmn;\u0026thinsp;2.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e86.82\u0026thinsp;\u0026plusmn;\u0026thinsp;2.20\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.855\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePCO (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e26.11\u0026thinsp;\u0026plusmn;\u0026thinsp;4.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e27.65\u0026thinsp;\u0026plusmn;\u0026thinsp;3.36\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.024\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLFW (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e57.51\u0026thinsp;\u0026plusmn;\u0026thinsp;5.03\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e56.72\u0026thinsp;\u0026plusmn;\u0026thinsp;4.26\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\u003ePCO ratio\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e0.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eChanges of PCO (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e2.42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;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=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e4.57\u0026thinsp;\u0026plusmn;\u0026thinsp;1.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e4.41\u0026thinsp;\u0026plusmn;\u0026thinsp;1.09\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.410\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLFCA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e9.53\u0026thinsp;\u0026plusmn;\u0026thinsp;2.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e9.22\u0026thinsp;\u0026plusmn;\u0026thinsp;2.78\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.313\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLTCA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e84.02\u0026thinsp;\u0026plusmn;\u0026thinsp;5.53\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e83.52\u0026thinsp;\u0026plusmn;\u0026thinsp;6.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.638\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePatella thickness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e15.08\u0026thinsp;\u0026plusmn;\u0026thinsp;2.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e17.61\u0026thinsp;\u0026plusmn;\u0026thinsp;15.33\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.210\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ePatella length\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e36.75\u0026thinsp;\u0026plusmn;\u0026thinsp;4.39\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e37.16\u0026thinsp;\u0026plusmn;\u0026thinsp;4.68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.618\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFJS\u003c/p\u003e \u003cp\u003eROM-3 days post-operation\u003c/p\u003e \u003cp\u003eROM-1year post-operation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e40.70\u0026thinsp;\u0026plusmn;\u0026thinsp;10.46\u003c/p\u003e \u003cp\u003e102.92\u0026thinsp;\u0026plusmn;\u0026thinsp;7.93\u003c/p\u003e \u003cp\u003e103.35\u0026thinsp;\u0026plusmn;\u0026thinsp;6.10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e38.44\u0026thinsp;\u0026plusmn;\u0026thinsp;9.54\u003c/p\u003e \u003cp\u003e97.34\u0026thinsp;\u0026plusmn;\u0026thinsp;5.49\u003c/p\u003e \u003cp\u003e100.52\u0026thinsp;\u0026plusmn;\u0026thinsp;4.97\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.210\u003c/p\u003e \u003cp\u003e\u0026lt;0.001\u003c/p\u003e \u003cp\u003e0.024\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe MP group was more advantageous in changes of PCO (MP group changes of PCO: 2.42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52 mm vs CR group changes of PCO: 3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11 mm p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), the post-operation PCO and PCO ratio was significantly less in the MP group (MP group PCO: 26.11\u0026thinsp;\u0026plusmn;\u0026thinsp;4.08mm vs CR group PCO: 27.65\u0026thinsp;\u0026plusmn;\u0026thinsp;3.36mm p\u0026thinsp;=\u0026thinsp;0.024; MP group PCO ratio: 0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 vs CR group PCO ratio: 0.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 p\u0026thinsp;=\u0026thinsp;0.001), there were no significant differences between the two groups in terms of others sagittal plane parameters (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The post-operative ROM was significantly better in the MP group in 3-days post-operation and the 12-months post-operation (3-days post-operation in MP group:102.92\u0026deg;\u0026plusmn;7.93 vs 3-days post-operation in CR group:97.34\u0026deg;\u0026plusmn;5.49 p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, 12-months post-operation in MP group:103.35\u0026thinsp;\u0026plusmn;\u0026thinsp;6.10 vs 12-months post-operation in CR group: 100.52\u0026thinsp;\u0026plusmn;\u0026thinsp;4.97 p\u0026thinsp;=\u0026thinsp;0.024) .\u003c/p\u003e \u003cp\u003eThere was no intraoperative complication in both groups. One case in the CR group had wound exudation, which healed after a pressure dressing.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThe most important finding of this study is that patients who performed MP-TKA achieved a better sagittal plane balance after the operation. There was significant difference in PCO, PCO ratio between the MP-TKA and the CR-TKA after surgery. The 3 days and 12 months post-operative ROM after MP-TKA was better than CR-TKA. However, these improvements of the ROM did not bring a superiority postoperative PROMs. The reason why MP-TKA achieves better PCO restoration may be related to the design of the polyethylene liner. During the MP-TKA operation procedure, there is no need to maintain femur rollback by the PCL benefit by the constrained bearing surface. Therefore, it is unnecessary to additionally increase the PCO to maintain the PCL tension during the operation.\u003c/p\u003e \u003cp\u003eMillions of patients undergo TKA every year. However, 20% of patients remain dissatisfied with their outcomes. It is generally accepted that total hip recovery is easier and quicker than TKA. Numerous prior studies have pointed out that CR and PS TKA fail to reproduce native knee kinematics reliably. The failure of traditional TKA designs to reproduce physiologic knee kinematics may contribute to patient dissatisfaction.[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] The MP design, mimics a natural knee joint and reproduces natural knee biomechanics with medial stability and lateral mobility.[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] Not only does this improve knee kinematics, but it also restores joint stability, knee flexion, and reduces wear on the polyethylene liner. The MP designs have reported better postoperative ROM and mid-term follow-up outcomes compared with PS-TKA.[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e] Hideki et al has shown that MP-TKA had a higher survival rate and better patient awareness of the prosthetic joint over 10 years follow-up.[\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e] In this study, MP-TKA also demonstrated excellent clinical outcomes, which were similar to the results of previous studies, indicating the reliability of MP-TKA.\u003c/p\u003e \u003cp\u003eIn recent years, an increasing number of studies have begun to recognize the importance of sagittal plane positioning of the prosthesis after TKA. Bellemans et al discovered that a small PCO would cause the collision between the femoral shaft and the posterior part of the tibial plateau when the knee joint was flexed, limiting the flexion range of the knee. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] Soda et al proposed the Posterior Condylar Offset Ratio (PCOR) in order to eliminate the influence of the size of femoral component on individual differences. [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] Onodera et al believed that excess PCO after operation may cause relative shortening of the posterior soft tissue, which might cause flexion contracture of the knee. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] Costanzo et al reported that changes in postoperative PCO would cause patellar clunk syndrome. [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e] Two recent studies have highlighted the importance in PCO restoration after revision TKA with improved outcome.[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e] Few studies have compared the PCO and clinical outcomes between different prostheses design. A finite element study shown that PCO changs magnitude influenced postoperative kinematics, especially for CR-TKA.[\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e] To our knowledge, this study is the only one that compared the postoperative PCO of MP-TKA and CR-TKA in X-ray photographs. In our study, all TKA retained the PCL, which enhances the comparability between the two groups. In this study, MP-TKA demonstrated potential advantages in restoring PCO.\u003c/p\u003e \u003cp\u003eFemur intramedullary localization and tibial extramedullary localization were used for all TKAs in this study. Femur intramedullary localization refers to the placing of the osteotomy guide mold in the femur medullary cavity. It is simple and easy to implement, so it has become the preferred positioning method for most orthopedic surgeons. The premise is that the long axis of the medullary cavity coincides with the anatomical axis of the femur on the coronal and sagittal planes. The intramedullary localization offers the advantage of a positioning process that is not susceptible to external interference. Comparing with intramedullary positioning, extramedullary tibial localization has fewer complications. With some surface bone markers, it can meet the requirements of determining the alignment of the lower limbs. To our knowledge, it has depended to a certain extent on the operator\u0026rsquo;s visual judgment and empirical operation to determine tibial osteotomy. Before tibial osteotomy, the positioning of the tibial extramedullary locator is essential. The tibial extramedullary guide should be parallel to the long axis of the tibia on the coronal and sagittal planes. However, the placement of the prosthesis after tibial osteotomy still has some deviation, due to the physiological curvature of the tibia.[\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e] In this study, both MP-TKA and CR-TKA demonstrated clinically acceptable PCO, PTS and FJS. Long-term follow-up will still be necessary in the future.\u003c/p\u003e \u003cp\u003eA good ROM is essential for daily life. When walking, the knee joint needs to be flexed at 60\u0026ndash;70 degrees. When going up or down stairs, the knee joint needs to be flexed at 90\u0026ndash;120 degrees. In Asia, patients may require an increased ROM to participate in religious activities, such as cross-legged sitting and kneeling.[\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e] Although a better ROM is theoretically more beneficial for the patient in their daily life, excessive postoperative ROM will increase patellofemoral pressure, which may result in anterior knee pain, excessive wear of the polyethylene liner, fracture of the patellar, and other complications.[\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e] Therefore, surgeons should consider comprehensive when performing the osteotomy to keep the PTS in a suitable range for normal individuals and to restore normal knee kinematics as much as possible. In our study, both groups of patients underwent the same surgical technique. The ROM in the MP-TKA group significantly improved, and there was no significant increase in complications. This is similar to the results of previous studies, demonstrating the superiority of MP.[\u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e] A better ROM might be related to the accurate restoration of the PCO and the re-establishment of balance in the knee.\u003c/p\u003e \u003cp\u003eSome studies have noted that in TKA surgery guided by the MA philosophy, changes in femoral rotation during postoperative lateral X-rays can result in medial and lateral posterior condyles that overlap entirely, rendering the image not a \u0026ldquo;true lateral knee radiograph\u0026rdquo;. Ignoring this discrepancy is misleading.[\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e33\u003c/span\u003e, \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e34\u003c/span\u003e] In our study, TKA guided by the restricted kinematic alignment (rKA) philosophy, femoral components are often placed in 0\u0026deg; rotation. \u0026ldquo;True lateral knee radiographs\u0026rdquo; are achieved in the postoperative radiograph, which reduces the misleading.\u003c/p\u003e \u003cp\u003eThe main strengths of this study were that clinical outcomes were recorded by blinded observers using standardized techniques with high observer agreement on all outcomes. Compared with the CR group, the MP group showed a better ROM in 3 days and 12 months post-operative. However, no significant difference was observed in FJS, which might be related to the ceiling effect of FJS.[\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e]\u003c/p\u003e \u003cp\u003eThere are several limitations in the literature involving the retrospective design of the study; the relatively small sample size is a notable limitation, patients were not randomized between the treatment group, selection bias is a relevant limitation. In addition, the patients who were operated by the same surgical team; however, this limits the generalizability of the findings. More generalizable results could be achieved through prospective, randomized controlled studies with larger sample sizes.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe MP design TKA achieves better sagittal plane balance compared with the CR design TKA. The reason may be related that it is unnecessary to additionally increase the PCO to maintain the PCL tension during the MP operation.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthics approval:\u003c/h2\u003e \u003cp\u003e The Institution\u0026rsquo;s Review Board of Peking Union Medical College Hospital gave ethical approval (Approval Number: K9408) for our retrospective study on November 05, 2025. All procedures were conducted in compliance with the guidelines of the Declaration of Helsinki.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eInformed consent:\u003c/strong\u003e \u003cp\u003e Informed consent was obtained from all individual participants included in the study.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eClinical trial number\u003c/strong\u003e \u003cp\u003eNot applicable\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication:\u003c/strong\u003e \u003cp\u003eNot applicable.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eCompeting interests:\u003c/strong\u003e \u003cp\u003eThe authors declare no conflict of interest.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis study was partially funded by the Natural Science Foundation of Beijing Municipality (Grant No. L252157).\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eMingyang Ma drafted the manuscript. Sen Liu, Hongjun Xu and Yang Yu performed the data collection and data analysis. Zhongyin Ji and Guiguan Wang performed the data interpretation. Zhaojing Yin and Yiyang Du participated in the coordination. Wenwei Qian conceived of the study. All authors read and approved the final manuscript.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eMaradit Kremers H, Larson DR, Crowson CS, Kremers WK, Washington RE, Steiner CA, Jiranek WA, Berry DJ (2015) Prevalence of Total Hip and Knee Replacement in the United States. 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BMC Musculoskelet Disord 23(1):222. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1186/s12891-022-05156-5\u003c/span\u003e\u003cspan address=\"10.1186/s12891-022-05156-5\" 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":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":"total knee arthroplasty, restricted kinematic alignment, cruciate retaining, medial-pivot","lastPublishedDoi":"10.21203/rs.3.rs-9201898/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9201898/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cb\u003eIntroduction:\u003c/b\u003e\u003c/p\u003e \u003cp\u003eAchieving sagittal plane balance is important to total knee arthroplasty (TKA) for providing mid-flexion stability and potentially increasing patient\u0026rsquo;s satisfaction. This study aimed to compare the sagittal plane parameters, range of motion (ROM), and patient-reported outcomes (PROMs) between patients received the cruciate retaining (CR) and the patients received medial-pivot (MP) in the restricted kinematic alignment TKA.\u003c/p\u003e\u003cp\u003e\u003cb\u003eMethods\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThis retrospective study including a total of 124 patients who underwent TKA in Department of Orthopedics of Peking Union Medical College Hospital between February 2024 and January 2025. Patients were assessed preoperatively and 12 months postoperatively. All patients taken X-ray imaging in pre-operation and on the third day after the operation. Clinical assessments including the Forgotten Joint Score (FJS), physical examination including the assessment of the active ROM of the knee. The HKA (Hip-Knee-Angle), LDFA (Lateral Distal Femoral Angle), MPTA (Medial Proximal Tibial Angle), LFCA (Lateral Femoral Component Angle), LTCA (Lateral Tibial Component Angle), patella thickness, patella length, posterior femoral condylar offset (PCO), Coronal femoral width (LFW), PCO ratio, and posterior tibial slope (PTS) were taken from the X-ray imaging.\u003c/p\u003e\u003cp\u003e\u003cb\u003eResults\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThere were 60 patients in the MP-TKA group and 64 patients in the CR-TKA group. Pre-operatively, there were no significant differences between the two groups in terms of demographic data, HKA, LDFA, MPTA, sagittal plane parameters, and FJS (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The MP group was more advantageous in changes of PCO (MP group changes of PCO: 2.42\u0026thinsp;\u0026plusmn;\u0026thinsp;1.52 mm vs CR group changes of PCO: 3.62\u0026thinsp;\u0026plusmn;\u0026thinsp;2.11 mm p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), the post-operation PCO and PCO ratio was significantly less in the MP group (MP group PCO: 26.11\u0026thinsp;\u0026plusmn;\u0026thinsp;4.08mm vs CR group PCO: 27.65\u0026thinsp;\u0026plusmn;\u0026thinsp;3.36mm p\u0026thinsp;=\u0026thinsp;0.024; MP group PCO ratio: 0.45\u0026thinsp;\u0026plusmn;\u0026thinsp;0.06 vs CR group PCO ratio: 0.48\u0026thinsp;\u0026plusmn;\u0026thinsp;0.05 p\u0026thinsp;=\u0026thinsp;0.001), there were no significant differences between the two groups in terms of the post-operation HKA, LDFA, MPTA and others sagittal plane parameters (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The post-operative ROM was significantly better in the MP group in 3-days post-operation and the 12-months post-operation (3-days post-operation in MP group:102.92\u0026deg;\u0026plusmn;7.93 vs 3-days post-operation in CR group:97.34\u0026deg;\u0026plusmn;5.49 p\u0026thinsp;\u0026lt;\u0026thinsp;0.001, 12-months post-operation in MP group:103.35\u0026thinsp;\u0026plusmn;\u0026thinsp;6.10 vs 12-months post-operation in CR group: 100.52\u0026thinsp;\u0026plusmn;\u0026thinsp;4.97 p\u0026thinsp;=\u0026thinsp;0.024) .\u003c/p\u003e\u003cp\u003e\u003cb\u003eConclusion\u003c/b\u003e\u003c/p\u003e \u003cp\u003eThe MP design achieves better sagittal plane balance compared with the CR design TKA.\u003c/p\u003e","manuscriptTitle":"The Medial Pivot design achieves better sagittal plane balance in the restricted kinematic alignment total knee arthroplasty","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-02 07:11:24","doi":"10.21203/rs.3.rs-9201898/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":"b413ad0b-35f9-4499-81b1-5b8a21dd120f","owner":[],"postedDate":"April 2nd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-20T14:12:36+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-02 07:11:24","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9201898","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9201898","identity":"rs-9201898","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}