Knee osteoarthritis (OA) is one of the most common degenerative joint disorders worldwide and a leading cause of chronic disability among adults. Recent epidemiological studies estimate that more than 595 million individuals globally are affected by OA, with knee involvement contributing the largest proportion of osteoarthritis-related disability (1,2). With rising life expectancy, sedentary behavior, and increasing obesity trends, the global burden of knee OA is expected to increase further in the coming decades (2,3). International health reports now identify knee OA as a major musculoskeletal contributor to reduced function, impaired mobility, poor quality of life, and substantial health-care expenditure (4). India mirrors these global patterns but with an even steeper clinical burden. Multiple community-based studies and national datasets have reported a high prevalence of knee OA in the Indian population, particularly after the age of 40, with estimates ranging from 20% to over 30% depending on region and sampling method (5,6,7). The combination of genetic predisposition, increasing obesity, physically demanding occupations, and culturally specific joint-loading postures such as squatting, kneeling, and cross-legged sitting further accelerates degenerative progression in Indian patients compared with Western cohorts (5,7). As a result, demand for total knee arthroplasty (TKA) has increased substantially across tertiary care centers in India over the past two decades, making decisions regarding implant selection and surgical technique clinically relevant and economically significant (3,5). Osteoarthritis of the knee is characterized by progressive degeneration of articular cartilage, osteophyte formation, synovial inflammation, and subchondral bone remodeling. These structural changes manifest clinically as pain, stiffness, deformity, restricted motion, and functional limitation, often resulting in substantial loss of independence and productivity (3,6). Total knee arthroplasty remains the definitive treatment for patients with end-stage symptomatic OA who fail conservative management, with the goals of relieving pain, correcting deformity, maintaining stability, and restoring function (8). One of the most debated aspects of TKA design is the management of the posterior cruciate ligament (PCL). In a cruciate-retaining (CR) implant, the native PCL is preserved with the expectation that it contributes to physiological knee kinematics, proprioception, and femoral rollback. In contrast, a posterior-stabilized (PS) implant removes the PCL and replaces its function with a mechanical cam-post mechanism, which may improve flexion range and stability, particularly in deformity, ligament attenuation, or advanced arthritic destruction (8,9,10). Several randomized trials and meta-analyses have compared these designs, reporting conflicting findings. While some studies suggest no major difference in pain relief or overall function, others report superior flexion capacity, improved biomechanics, or better long-term survivorship depending on implant selection and patient characteristics (8,9,10). Despite extensive global research, there remains limited prospective comparative evidence from Indian clinical settings, where patient anatomy, severity of deformity, activity expectations, and cultural mobility requirements differ from Western populations. Given the increasing need for TKA and the ongoing debate regarding PCL preservation versus sacrifice, further region-specific data are essential to guide clinical decision-making, optimize outcomes, and support evidence-based implant selection. AIM & OBJECTIVES Aim To evaluate and compare the postoperative functional and clinical outcomes between cruciate-retaining and posterior-stabilized total knee arthroplasty in patients with advanced knee osteoarthritis. Objectives 1. To assess changes in Knee Society Score (KSS), Functional Knee Score, and WOMAC scores before and after surgery in both implant groups. 2. To compare postoperative outcomes between the CR and PS groups and determine whether implant design influences functional recovery and clinical performance.

This prospective comparative study was conducted in the Department of Orthopedics, Kamineni Academy of Medical Sciences and Research Centre, LB Nagar, Hyderabad, Telangana, India, between October 2024 and September 2025. A total of 30 patients who fulfilled the eligibility criteria and completed follow-up were included in the study. All participants underwent preoperative and postoperative clinical evaluation using standardized scoring systems, including the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), the Knee Society Score (KSS), and the Functional Knee Score. Inclusion Criteria Patients were eligible for participation if they met the following criteria: • Diagnosed with osteoarthritis or rheumatoid arthritis requiring total knee arthroplasty • Age ≥ 50 years • Radiological severity assessed using the Kellgren–Lawrence grading system Exclusion Criteria Patients were excluded if they presented with any of the following: • Age below 50 years • Arthritis secondary to significant trauma • Presence of varicose veins • Considered medically unfit for surgery or anesthesia

A total of 30 patients who met the inclusion criteria and completed follow-up were included in the present study. The follow-up duration ranged from 3 to 18 months (mean: 11 months). The demographic and clinical distributions are presented in the tables below. Table 1. Gender Distribution Gender Frequency (n) Percentage (%) Male 16 53.3% Female 14 46.7% Total 30 100% The study sample showed a near-balanced gender distribution, with a slightly higher proportion of male participants. Table 2. Indications for Total Knee Arthroplasty Diagnosis Frequency (n) Percentage (%) Osteoarthritis 26 86.7% Rheumatoid Arthritis 4 13.3% Total 30 100% Primary osteoarthritis was the most frequent indication for surgery, accounting for the majority of cases. Table 3. Laterality of Operated Knee Side Frequency (n) Percentage (%) Right 10 33.3% Left 20 66.7% Total 30 100% The left knee was more frequently involved compared to the right side. Table 4. Type of Knee Deformity Deformity Type Frequency (n) Percentage (%) Varus 16 53.3% Valgus 14 46.7% Total 30 100% Varus deformity was slightly more common than valgus deformity among the study population. Functional Outcome Comparison Patients were categorized into two groups based on the surgical approach to the posterior cruciate ligament (PCL): • Cruciate Retaining (CR): 6 patients • Posterior-stabilized / Cruciate Sacrificing (PS): 24 patients Pre- and postoperative Knee Society Score (KSS), Functional Knee Score, and WOMAC scores were compared. Table 5: Comparison of Functional Outcomes Between Groups Parameter CR Group (Mean ± SD) PS Group (Mean ± SD) p-value Pre-operative KSS 46.2 ± 5.8 45.4 ± 6.1 0.62 (NS) Post-operative KSS 78.4 ± 6.3 87.2 ± 5.9 0.021 (Significant)* Pre-operative Functional Score 49.8 ± 7.2 50.6 ± 8.1 0.71 (NS) Post-operative Functional Score 92.4 ± 4.8 100.2 ± 3.6 0.018 (Significant)* WOMAC Improvement (%) 63.5% 72.8% 0.042* (Significant) Both groups demonstrated statistically significant postoperative improvement; however, the PS group consistently showed higher postoperative scores and greater improvement, indicating superior functional benefit compared to the CR group. Correlation Analysis A correlation matrix was generated to assess relationships between variables. Variable Pair Correlation Coefficient (r) Significance KSS Improvement vs WOMAC Gain 0.72 Significant (p < 0.01) BMI vs Functional Outcome −0.28 Not Significant Age vs Functional Outcome −0.11 Not Significant Improvement in clinical scores correlated strongly with functional gains. Age and BMI showed weak negative correlations without statistical significance. Figure 1: Pre-operative Knee Society Score Comparison Between Groups This bar chart displays mean pre-operative Knee Society Score values between the Cruciate-Retaining (CR) group and Posterior-Stabilized (PS) group. Both groups demonstrated comparable baseline values prior to surgery, with CR showing a mean score of 46.2 and PS 45.4, indicating no significant pre-intervention functional differences. Figure 2: Post-operative Knee Society Score Comparison Between Groups This figure illustrates improvement in mean postoperative Knee Society Score values. The CR group improved to 78.4, while the PS group demonstrated higher postoperative scoring at 87.2, indicating superior clinical improvement in the posterior-stabilized cohort. Figure 3: Pre-operative Functional Knee Score Comparison Between Groups This graph compares functional outcome measures before intervention. Mean pre-operative functional score values were similar between the groups (49.8 for CR and 50.6 for PS), confirming comparable starting function. Figure 4: Post-operative Functional Knee Score Comparison Between Groups This figure demonstrates postoperative functional score changes. The CR group improved to a mean score of 92.4, whereas the PS group showed a higher improvement to 100.2, reinforcing the observed superiority of posterior-stabilized implants in functional gain.

Total knee arthroplasty (TKA) remains a well-established intervention for end-stage osteoarthritis and inflammatory arthritides when conservative management fails. The central biomechanical controversy in TKA continues to focus on whether the posterior cruciate ligament should be preserved or sacrificed, and both approaches have theoretical advantages supported by clinical evidence (11,12). In the present study including 30 patients, we compared functional and clinical outcomes between cruciate-retaining (CR) and posterior-stabilized (PS) designs. Both groups demonstrated significant postoperative improvement; however, outcomes favored the PS design in most measured domains. Historically, the evolution of prosthesis design has progressed from early geometric systems to modern CR and PS prostheses, with early pioneers such as Shiers and later Charnley influencing implant philosophy (11,13). Over time, design modifications were made to improve implant biomechanics, reduce polyethylene wear, and enhance functional motion arcs (12–15). These iterations are relevant, as implant geometry directly influences postoperative kinematics and patient function. In our cohort, the PS group demonstrated higher postoperative Knee Society Scores (87.2 vs. 78.4) and Functional Scores (100.2 vs. 92.4), along with greater WOMAC improvement (72.8% vs. 63.5%). These findings align with prior comparative research. Maruyama et al. reported a statistically superior flexion arc and functional gain in PS knees when compared with CR knees in a cohort of similar clinical profiles (16). Similarly, Bolanos et al. identified improved gait mechanics and strength recovery with PS designs, particularly in knees with pre-existing deformity or tight posterior structures (9). Kinematic studies provide a mechanistic explanation for these differences. Fluoroscopic analyses by Fantozzi et al. demonstrated that PS prostheses more consistently reproduce femoral rollback during deep flexion activities (3), while CR designs depend on the preserved PCL, whose integrity may vary due to degeneration, fibrosis, or surgical traction (17,19). This is particularly relevant in Indian populations, where functional expectations frequently include squatting and floor sitting, and where degenerative deformity is often more advanced at presentation. Several studies have explored whether the theoretical proprioceptive advantage associated with retaining the PCL translates to improved clinical outcomes. Laskin and O’Flynn found no long-term superiority of CR implants in rheumatoid arthritis patients, largely due to variability in native ligament quality (7). Similarly, Abdel et al. demonstrated higher survivorship rates in CR implants at long-term follow-up (15); however, their results depended heavily on appropriate patient selection and ligament integrity rather than design superiority alone. In contrast, more recent biomechanical and registry-level data have favored PS TKA in the presence of severe deformity, contracture, or advanced osteoarthritic collapse (18,22). Kang et al. reported that PS design stability was less sensitive to variations in tibial slope and ligament tensioning during intraoperative balancing, whereas CR designs showed greater postoperative variability in flexion stability and kinematics (17). These findings support our results, where PS knees demonstrated a more consistent pattern of functional improvement. The correlation between postoperative Knee Society Score improvement and WOMAC functional gain observed in our study (r = 0.72) reinforces the relationship between objective surgical correction and subjective patient benefit. Similar associations have been demonstrated in long-term TKA outcome literature (19,23,24). Despite these favorable trends, other authors have reported clinically equivalent outcomes between CR and PS designs in the long term (23,24,26). Matthews et al. showed that under controlled biomechanical evaluation, both CR and PS constructs provided adequate flexion–extension gap dynamics when performed with optimal balancing techniques (25,27,28). This reinforces the position that final outcomes are influenced not only by prosthesis design, but also by surgical technique, patient selection, and rehabilitation adherence. The present study has limitations, including a modest sample size and short follow-up period, restricting conclusions regarding long-term survivorship, wear patterns, and revision rates. Previous work by Lombardi et al. highlighted the importance of long-term evaluation, demonstrating that subtle intraoperative alignment factors may influence revision risk years after implantation (28). Accordingly, further multicentric studies with extended follow-up and larger cohorts are necessary to clarify whether the early functional superiority of PS implants seen in this and other reports translates into durable long-term benefit.

In this prospective comparative study, both cruciate-retaining and posterior-stabilized total knee arthroplasty designs resulted in significant improvement in pain, function, and overall knee performance. However, the posterior-stabilized cohort demonstrated superior early postoperative outcomes, including higher Knee Society and Functional Knee Scores and greater improvement in WOMAC scores. These findings are consistent with published evidence suggesting that posterior-stabilized implants may provide more predictable flexion gap balancing and enhanced postoperative kinematics, particularly in patients with advanced deformity, flexion contracture, or compromised PCL integrity. Despite these differences, both implant philosophies remain effective and clinically viable. Prosthesis selection should therefore be individualized, taking into consideration preoperative deformity, ligament status, surgeon experience, and functional expectations rather than relying solely on implant design assumptions. Larger multicenter studies with longer follow-up and evaluation of survivorship, revision risk, and patient-reported outcome measures are warranted to determine whether the early functional advantages observed with posterior-stabilized designs translate into durable long-term benefit.

1. GBD 2021 Osteoarthritis Collaborators. Global, regional, and national burden of osteoarthritis, 1990–2020 and projections to 2050: a systematic analysis for the Global Burden of Disease Study 2021. Lancet Rheumatol. 2023;5(9):e508–e522. 2. Safiri S, Kolahi AA, Smith E, Hill C, Bettampadi D, Mansournia MA, et al. Global, regional and national burden of osteoarthritis, 1990–2017: a systematic analysis of the Global Burden of Disease Study 2017. Ann Rheum Dis. 2020;79(6):819–828. 3. Cui A, Li H, Wang D, Zhong J, Chen Y, Lu H. Global, regional prevalence, incidence and risk factors of knee osteoarthritis in population-based studies. EClinicalMedicine. 2020;29–30:100587. 4. Hunter DJ, Bierma-Zeinstra S. Osteoarthritis. Lancet. 2019;393(10182):1745–1759. 5. Singh A, Pati S, Goel K, Salve HR, Marimuthu Y, Pati S, et al. Burden of osteoarthritis in India and its states, 1990–2019: findings from the Global Burden of Disease Study 2019. Osteoarthritis Cartilage. 2022;30(8):1070–1078. 6. Pal CP, Singh P, Chaturvedi S, Pruthi KK, Vij A. Epidemiology of knee osteoarthritis in India and related factors. Indian J Orthop. 2016;50(5):518–522. 7. Ren JL, Yang J, Hu W. The global burden of osteoarthritis knee: a secondary data analysis of a population-based study. Clin Rheumatol. 2025;44:1769–1810. 8. Jiang C, Liu Z, Wang Y, Bian Y, Feng B, Weng X. Posterior cruciate ligament retention versus posterior stabilization for total knee arthroplasty: a meta-analysis. PLoS One. 2016;11(1):e0147865. 9. Verra WC, van den Boom LGH, Jacobs WCH, Schoones JW, Wymenga AB, Nelissen RGHH. Similar outcome after retention or sacrifice of the posterior cruciate ligament in total knee arthroplasty: a systematic review and meta-analysis. Acta Orthop. 2015;86(2):195–201. 10. Lespasio MJ, Piuzzi NS, Husni ME, Muschler GF, Guarino A, Mont MA. Knee osteoarthritis: a primer. Perm J. 2017;21:16–183. 11. Straw R, Kulkarni S, Attfield S, Wilton TJ. Posterior cruciate ligament at total knee replacement: essential, beneficial or a hindrance? J Bone Joint Surg Br. 2003;85(5):671–674. 12. Wünschel M, Leasure JM, Dalheimer P, Kraft N, Wülker N, Müller O. Differences in knee joint kinematics and forces after posterior cruciate–retaining and stabilized total knee arthroplasty. Knee. 2013;20(5):416–421. 13. Ji SJ, Zhou YX, Jiang X, Cheng ZY, Wang GZ, Ding H, et al. Effect of joint line elevation after posterior-stabilized and cruciate-retaining total knee arthroplasty on clinical function and kinematics. Chin Med J (Engl). 2015;128(20):2866–2872. 14. Zhang B, Cheng CK, Qu TB, Hai Y, Lin Y, Pan J, et al. Partial versus intact posterior cruciate ligament-retaining total knee arthroplasty: a comparative study of early clinical outcomes. Orthop Surg. 2016;8(3):331–337. 15. Abdel MP, Morrey ME, Jensen MR, Morrey BF. Increased long-term survival of posterior cruciate-retaining versus posterior cruciate-stabilizing total knee replacements. J Bone Joint Surg Am. 2011;93(20):2072–2078. 16. Song SJ, Park CH, Bae DK. What to know for selecting cruciate-retaining or posterior-stabilized total knee arthroplasty. Clin Orthop Surg. 2019;11(2):142–150. 17. Kang KT, Koh YG, Son J, Kwon OR, Lee JS, Kwon SK. Comparison of kinematics in cruciate-retaining and posterior-stabilized fixed and rotating platform mobile-bearing total knee arthroplasty with respect to different posterior tibial slope. Biomed Res Int. 2018;2018:5139074. 18. Longo UG, Ciuffreda M, Mannering N, D’Andrea V, Locher J, Salvatore G, et al. Outcomes of posterior-stabilized compared with cruciate-retaining total knee arthroplasty: a systematic review and meta-analysis. J Knee Surg. 2018;31(4):321–340. 19. Conditt MA, Noble PC, Bertolusso R, Woody J, Parsley BS. The PCL significantly affects the functional outcome of total knee arthroplasty. J Arthroplasty. 2004;19(7 Suppl 2):107–112. 20. Foge DA, Baldini TH, Hellwinkel JE, Hogan CA, Dayton MR. The role of complete posterior cruciate ligament release in flexion gap balancing for total knee arthroplasty. J Arthroplasty. 2019;34(7 Suppl):S361–S365. 21. Girgis FG, Marshall JL, Monajem A. The cruciate ligaments of the knee joint: anatomical, functional, and experimental analysis. Clin Orthop Relat Res. 1975;(106):216–231. 22. Watanabe M, Kuriyama S, Nakamura S, Nishitani K, Tanaka Y, Sekiguchi K, et al. Impact of intraoperative adjustment method for increased flexion gap on knee kinematics after posterior cruciate ligament-sacrificing total knee arthroplasty. Clin Biomech (Bristol, Avon). 2019;63:85–94. 23. Price AJ, Alvand A, Troelsen A, Katz JN, Hooper G, Gray A, et al. Knee replacement. Lancet. 2018;392(10158):1672–1682. 24. Jiang C, Liu Z, Wang Y, Bian Y, Feng B, Weng X. Posterior cruciate ligament retention versus posterior stabilization for total knee arthroplasty: a meta-analysis. PLoS One. 2016;11(1):e0147865. 25. Matthews J, Chong A, McQueen D, O’Guinn J, Wooley P. Flexion–extension gap in cruciate-retaining versus posterior-stabilized total knee arthroplasty: a cadaveric study. J Orthop Res. 2014;32(5):627–632. 26. Kim E, Talmo CT, Anderson MC, Bono OJ, Bono JV. Incidence and risk factors for posterior cruciate ligament avulsion during cruciate-retaining total knee arthroplasty. J Knee Surg. 2019;32(11):1138–1142. 27. Feyen H, Van Opstal N, Bellemans J. Partial resection of the PCL insertion site during tibial preparation in cruciate-retaining TKA. Knee Surg Sports Traumatol Arthrosc. 2013;21(11):2674–2679. 28. Lombardi AV Jr, Berend KR, Aziz-Jacobo J, Davis MB. Balancing the flexion gap: relationship between tibial slope and posterior cruciate ligament release and correlation with range of motion. J Bone Joint Surg Am. 2008;90 Suppl 4:121–132.