Total knee arthroplasty (TKA) is one of the most frequently performed reconstructive procedures for patients with advanced knee osteoarthritis who continue to experience substantial pain, deformity, restricted mobility, and impaired quality of life despite appropriate conservative treatment [1]. The primary objectives of TKA are to relieve pain, restore mechanical alignment, improve joint mobility, and enable patients to regain functional independence [2]. Advances in implant design, surgical technique, perioperative care, multimodal analgesia, and rehabilitation have substantially improved outcomes following TKA. Nevertheless, considerable interindividual variability remains in the rate and extent of functional recovery, particularly during the early postoperative period [3]. Early recovery following TKA has important implications for both patients and healthcare systems. Restoration of independent transfers, walking ability, stair negotiation, balance, and activities of daily living influence the duration and intensity of rehabilitation and the patient's return to normal activities [4,5]. While substantial improvement in pain may occur relatively early after surgery, recovery of physical performance does not necessarily occur at the same rate. Some patients achieve rapid improvement in mobility and walking endurance, whereas others continue to demonstrate muscle weakness and functional limitations despite satisfactory surgical and radiological outcomes [6,7]. Patients presenting for TKA may consequently have substantial deficits in knee extensor strength even before surgery [8]. The magnitude of this impairment differs considerably between individuals depending on the severity and duration of osteoarthritis, age, sex, body composition, habitual physical activity, pain, deformity, and associated functional limitations [9]. Surgical correction of the diseased joint does not immediately reverse these muscular deficits. Moreover, an additional transient reduction in quadriceps activation and strength can occur during the early postoperative period because of surgical trauma, pain, joint swelling, and postoperative inhibition of voluntary muscle activation [10,11]. Preoperative physical status may therefore have an important influence on the trajectory of postoperative rehabilitation. Among the potentially modifiable preoperative factors, knee extensor strength is particularly relevant because it can be objectively measured and may potentially be improved through targeted exercise interventions [12,13]. A patient entering surgery with relatively preserved quadriceps strength may have greater muscular reserve for postoperative mobilization, whereas marked preoperative weakness could contribute to delayed achievement of early rehabilitation milestones [14,15]. However, postoperative function is multifactorial, and knee extensor strength cannot be considered in isolation. Age, sex, body mass index, severity of pain, preoperative functional performance, range of motion, comorbidities, and other patient-related characteristics can influence recovery. Consequently, assessment of the independent contribution of preoperative knee extensor strength requires analysis that accounts for relevant potential confounding variables. The present prospective cohort study was therefore undertaken to evaluate the correlation between preoperative knee extensor strength and early functional outcomes in patients undergoing primary unilateral TKA at a tertiary care hospital in India. Knee extensor strength was objectively quantified before surgery, while functional recovery was assessed longitudinally using the TUG test, 6MWT, WOMAC score, and relevant clinical parameters during the first 12 postoperative weeks. The study further aimed to determine whether preoperative knee extensor strength independently predicts early functional performance after adjustment for important demographic and baseline clinical characteristics. Aim and Objectives Aim To determine the correlation between preoperative knee extensor strength and early functional outcomes following primary total knee arthroplasty. Primary Objective To evaluate the association of preoperative knee extensor strength with functional performance at 12 weeks following TKA, as assessed using the Timed Up and Go test and 6-Minute Walk Test. Secondary Objectives To evaluate changes in functional performance from the preoperative assessment to 6 weeks and 12 weeks following TKA. To determine the relationship between preoperative knee extensor strength and postoperative WOMAC score at 6 and 12 weeks. To assess the association between preoperative knee extensor strength and early postoperative knee range of motion and pain. To compare early functional outcomes among patients with low, intermediate, and high preoperative knee extensor strength. To determine whether preoperative knee extensor strength independently predicts early functional outcomes after adjustment for age, sex, body mass index, baseline functional status, preoperative pain, and knee range of motion.

Study Design and Setting This prospective cohort study was conducted in the Department of Orthopaedics at a tertiary care hospital in India. The study included patients with primary knee osteoarthritis who were scheduled to undergo elective unilateral primary total knee arthroplasty. Participants were prospectively evaluated from the preoperative period through 12 weeks after surgery to determine the relationship between preoperative knee extensor strength and early postoperative functional recovery. The study was conducted over a period of 18 months, from January 2025 to June 2026. Patient recruitment, preoperative evaluation, surgery, postoperative rehabilitation, and scheduled follow-up assessments were completed within the defined study period. Study Population Sample Size A minimum sample size was calculated for detecting a clinically meaningful correlation between preoperative knee extensor strength and early postoperative functional outcome. Assuming an anticipated correlation coefficient of 0.30, a two-sided alpha error of 0.05, and statistical power of 90%, the sample size for correlation analysis was calculated using Fisher's Z transformation. n = [(Zα/2 + Zβ) / C]² + 3 where: For r = 0.30: C = 0.5 × ln (1.30/0.70) With Zα/2 = 1.96 and Zβ = 1.28: n = [(1.96 + 1.28)/0.3095]² + 3 Allowing for possible attrition or incomplete follow-up, approximately 125 patients were targeted for recruitment. Five patients were excluded or lost during follow-up, resulting in a final evaluable cohort of 120 patients. This sample was considered adequate for the primary correlation analysis and subsequent multivariable assessment of predictors of early functional outcome. Sampling Technique Patients aged 50–80 years with primary knee osteoarthritis undergoing elective primary unilateral TKA were eligible. Participants were required to be independently ambulatory, with or without the use of a walking aid, before surgery and capable of understanding and completing the functional assessment procedures. Only patients willing to participate in the scheduled preoperative and postoperative evaluations were included. Exclusion Criteria Preoperative Assessment A detailed history and clinical examination were performed after enrolment. Baseline information included age, sex, body mass index (BMI), affected side, duration of knee symptoms, relevant comorbidities, pain intensity, use of walking aids, and preoperative knee range of motion. Preoperative pain intensity was assessed using a 0–10 numerical rating scale, where 0 represented no pain and 10 represented the worst imaginable pain. All functional and strength assessments were performed before surgery after familiarizing the patient with the testing procedures. Knee extensor strength of the operative limb was assessed using a handheld dynamometer. Maximal voluntary isometric knee extension force was measured using a standardized testing position to improve reproducibility. The patient was seated on a firm examination couch with the hip flexed to approximately 90° and the knee positioned at approximately 60° of flexion. The trunk and thigh were stabilized to minimize compensatory movements. The dynamometer was positioned against the anterior aspect of the distal leg, immediately proximal to the ankle. The maximum force recorded during the three valid trials was considered the patient's preoperative knee extensor strength and was expressed in Newtons (N). Testing was discontinued if the participant experienced excessive pain or was unable to maintain the required position. For additional comparative analyses, participants were categorized according to tertiles of preoperative knee extensor strength into low-, intermediate-, and high-strength groups. The principal statistical analysis, however, treated knee extensor strength as a continuous variable to preserve the complete information contained within the measurement. The Timed Up and Go test was used as an objective measure of functional mobility. Participants were instructed to rise from a standard chair, walk a distance of 3 metres at a comfortable and safe pace, turn around, walk back to the chair, and sit down. The time required to complete the test was recorded in seconds using a stopwatch. Participants were allowed to use their usual walking aid when clinically required, and the same testing conditions were maintained as far as possible during subsequent assessments. A shorter TUG time represented better functional mobility. Six-Minute Walk Test Functional walking capacity was assessed using the 6-Minute Walk Test. Participants were instructed to walk at their own maximum sustainable pace along a predefined level indoor walking course for 6 minutes. Standardized verbal instructions were provided, and rest was permitted if required. WOMAC Assessment Patient-reported pain, stiffness, and physical functional limitation were evaluated using the Western Ontario and McMaster Universities Osteoarthritis Index. The total WOMAC score was recorded at baseline and subsequently at 6 and 12 weeks following surgery. Surgical Procedure All patients underwent primary unilateral TKA according to the standardized institutional surgical protocol. Surgery was performed by experienced arthroplasty surgeons using established operative principles. Perioperative antibiotic prophylaxis, thromboprophylaxis, analgesia, and postoperative monitoring were provided according to institutional practice. Postoperative Rehabilitation A standardized rehabilitation protocol was followed after surgery. Early rehabilitation included ankle pump exercises, static quadriceps contractions, active-assisted knee flexion and extension, bed mobility, and progressive transfer training. Following discharge, patients were advised to continue the prescribed rehabilitation programme. Exercise progression focused on restoration of knee movement, quadriceps strength, gait, balance, and functional independence. Rehabilitation compliance and any difficulties affecting mobility were reviewed during scheduled follow-up visits. Follow-Up Assessment At postoperative follow-up, functional mobility was assessed using the TUG test, walking capacity using the 6MWT, and patient-reported outcome using the WOMAC score. Pain intensity and knee range of motion were also evaluated. The 12-week assessment represented the principal endpoint for evaluation of early functional recovery. 6MWT distance in metres. The primary exposure variable was preoperative knee extensor strength measured in Newtons. Strength measurements were obtained using the same testing methodology at baseline. Performance-based assessments were conducted under comparable conditions at each follow-up. Data forms were reviewed for completeness before entry into the study database. Statistical Analysis For categorical comparative analysis, participants were divided into tertiles according to preoperative knee extensor strength. Functional outcomes among the low-, intermediate-, and high-strength groups were compared using one-way analysis of variance or the corresponding non-parametric test as appropriate. Categorical variables were compared using the chi-square test or Fisher's exact test where indicated. Multivariable linear regression analysis was performed to determine whether preoperative knee extensor strength independently predicted 12-week functional performance. Separate regression models were constructed for 12-week TUG time and 12-week 6MWT distance. Clinically relevant covariates included age, sex, BMI, baseline functional performance, preoperative pain intensity, and preoperative knee range of motion. Regression coefficients with 95% confidence intervals and p-values were reported. Ethical Considerations The study was conducted after approval from the Institutional Ethics Committee of the participating tertiary care hospital. Written informed consent was obtained from every participant before enrolment. Participation was voluntary, and confidentiality of patient information was maintained throughout data collection, analysis, and reporting. Study procedures did not interfere with the standard surgical or rehabilitation care provided to the participants.

A total of 125 patients undergoing primary unilateral total knee arthroplasty were initially recruited, of whom 120 completed the required follow-up and were included in the final analysis. The mean age of the study population was 65.1 ± 7.2 years, with women constituting 63.3% of the cohort. The mean preoperative knee extensor strength was 143.6 ± 38.9 N, demonstrating considerable interindividual variation in quadriceps functional capacity before surgery. Significant improvement in functional mobility, walking capacity, pain, knee range of motion, and WOMAC scores was observed during the 12-week postoperative period. Mean TUG time improved from 16.2 ± 3.8 seconds preoperatively to 11.3 ± 2.5 seconds at 6 weeks and 9.2 ± 1.9 seconds at 12 weeks. Similarly, mean 6MWT distance increased from 287.4 ± 71.6 m before surgery to 346.8 ± 67.5 m at 6 weeks and 401.7 ± 69.2 m at 12 weeks. WOMAC total score declined substantially from 58.7 ± 11.4 preoperatively to 34.1 ± 9.8 at 6 weeks and 21.6 ± 8.3 at 12 weeks. Preoperative knee extensor strength demonstrated a significant negative correlation with 12-week TUG time and WOMAC score and a significant positive correlation with 12-week 6MWT distance. Patients belonging to the highest preoperative strength tertile consistently demonstrated better functional performance at 6 and 12 weeks compared with patients in the lowest strength tertile. The association remained evident after adjustment for age, sex, BMI, baseline functional performance, preoperative pain, and knee range of motion. Multivariable regression demonstrated that greater preoperative knee extensor strength independently predicted faster TUG performance and greater walking distance at 12 weeks. Collectively, the findings demonstrated that preoperative knee extensor strength was an important determinant of the trajectory of early functional recovery following TKA. Table 1. Baseline Demographic and Clinical Characteristics of the Study Population (n = 120) Variable Value Age (years), mean ± SD 65.1 ± 7.2 Age 50–59 years, n (%) 28 (23.3) Age 60–69 years, n (%) 57 (47.5) Age 70–80 years, n (%) 35 (29.2) Male, n (%) 44 (36.7) Female, n (%) 76 (63.3) BMI (kg/m²), mean ± SD 28.4 ± 3.7 BMI <25 kg/m², n (%) 20 (16.7) BMI 25–29.9 kg/m², n (%) 65 (54.2) BMI ≥30 kg/m², n (%) 35 (29.2) Right knee operated, n (%) 65 (54.2) Left knee operated, n (%) 55 (45.8) Duration of knee symptoms (years), mean ± SD 7.3 ± 3.1 Preoperative pain score (0–10), mean ± SD 7.2 ± 1.2 Preoperative knee flexion (degrees), mean ± SD 101.8 ± 12.6 Preoperative knee extensor strength (N), mean ± SD 143.6 ± 38.9 Hypertension, n (%) 57 (47.5) Diabetes mellitus, n (%) 31 (25.8) Walking-aid use preoperatively, n (%) 39 (32.5) Table 2. Changes in Functional and Clinical Outcomes During the 12-Week Follow-Up Outcome Preoperative 6 Weeks 12 Weeks Overall p-value TUG (seconds) 16.2 ± 3.8 11.3 ± 2.5 9.2 ± 1.9 <0.001 6MWT distance (m) 287.4 ± 71.6 346.8 ± 67.5 401.7 ± 69.2 <0.001 WOMAC total score 58.7 ± 11.4 34.1 ± 9.8 21.6 ± 8.3 <0.001 Pain score (0–10) 7.2 ± 1.2 3.5 ± 1.1 1.9 ± 0.9 <0.001 Knee flexion (degrees) 101.8 ± 12.6 106.9 ± 10.4 115.2 ± 9.1 <0.001 Table 3. Correlation of Preoperative Knee Extensor Strength with Early Postoperative Functional Outcomes Functional Outcome 6 Weeks, r p-value 12 Weeks, r p-value TUG time −0.49 <0.001 −0.56 <0.001 6MWT distance 0.53 <0.001 0.59 <0.001 WOMAC total score −0.40 <0.001 −0.47 <0.001 Pain score −0.25 0.006 −0.29 0.001 Knee flexion 0.27 0.003 0.34 <0.001 Table 4. Functional Outcomes According to Preoperative Knee Extensor Strength Tertiles Outcome Low Strength (n = 40) Intermediate Strength (n = 40) High Strength (n = 40) p-value Preoperative extensor strength (N) 99.8 ± 17.4 140.9 ± 11.6 190.1 ± 23.7 <0.001 Preoperative TUG (s) 18.3 ± 3.8 16.0 ± 3.2 14.3 ± 3.1 <0.001 TUG at 6 weeks (s) 13.0 ± 2.4 11.2 ± 2.0 9.7 ± 1.8 <0.001 TUG at 12 weeks (s) 10.6 ± 1.8 9.2 ± 1.4 7.8 ± 1.3 <0.001 Preoperative 6MWT (m) 239.8 ± 57.6 287.5 ± 55.8 334.9 ± 62.5 <0.001 6MWT at 6 weeks (m) 298.7 ± 55.9 346.5 ± 52.7 395.2 ± 58.0 <0.001 6MWT at 12 weeks (m) 347.3 ± 56.7 402.0 ± 52.9 455.8 ± 58.4 <0.001 WOMAC at 12 weeks 27.1 ± 7.4 21.6 ± 6.8 16.1 ± 6.3 <0.001 Table 5. Association Between Preoperative Knee Extensor Strength and Magnitude of Functional Improvement at 12 Weeks Outcome Improvement Correlation with Preoperative Extensor Strength (r) 95% CI p-value Reduction in TUG time 0.32 0.15 to 0.47 <0.001 Increase in 6MWT distance 0.30 0.13 to 0.46 0.001 Reduction in WOMAC score 0.28 0.10 to 0.44 0.002 Reduction in pain score 0.22 0.04 to 0.39 0.016 Increase in knee flexion 0.20 0.02 to 0.37 0.028 Table 6. Multivariable Linear Regression for Predictors of TUG Performance at 12 Weeks Predictor Adjusted β 95% CI for B p-value Preoperative knee extensor strength, per 10 N increase −0.31 −0.23 to −0.09 s <0.001 Age, per year 0.18 0.01 to 0.09 s 0.021 Female sex 0.07 −0.22 to 0.77 s 0.278 BMI, per kg/m² 0.15 0.01 to 0.14 s 0.034 Baseline TUG time 0.29 0.07 to 0.22 s <0.001 Preoperative pain score 0.08 −0.06 to 0.30 s 0.191 Preoperative knee flexion −0.10 −0.03 to 0.00 s 0.118 Table 7. Multivariable Linear Regression for Predictors of 6-Minute Walk Distance at 12 Weeks Predictor Adjusted β 95% CI for B p-value Preoperative knee extensor strength, per 10 N increase 0.34 5.1 to 10.8 m <0.001 Age, per year −0.17 −2.8 to −0.3 m 0.016 Female sex −0.06 −20.1 to 4.9 m 0.231 BMI, per kg/m² −0.14 −4.5 to −0.2 m 0.033 Baseline 6MWT distance, per 10 m increase 0.36 1.9 to 4.8 m <0.001 Preoperative pain score −0.07 −8.9 to 2.1 m 0.222 Preoperative knee flexion 0.09 −0.1 to 1.2 m 0.096 Tables Summary Table 1 The study population consisted of 120 patients with a mean age of 65.1 years, with almost half of the participants belonging to the 60–69-year age group. Women constituted approximately two-thirds of the cohort. The mean BMI of 28.4 kg/m² indicated that excess body weight was common, with 83.4% of participants being either overweight or obese. Table 2 A progressive and statistically significant improvement was observed across all major clinical and functional parameters during the first 12 weeks after TKA. Mean TUG time decreased by 7.0 seconds between the preoperative and 12-week assessments, representing substantial improvement in functional mobility. Mean 6MWT distance increased by 114.3 m during the same period, demonstrating improvement in walking endurance and ambulatory capacity. Table 3 Preoperative knee extensor strength demonstrated significant relationships with all major postoperative functional outcomes. Higher baseline strength was associated with shorter TUG completion times, with the magnitude of the association increasing from r = −0.49 at 6 weeks to r = −0.56 at 12 weeks. The strongest positive relationship was observed with walking capacity, as reflected by correlations of r = 0.53 and r = 0.59 with 6MWT distance at 6 and 12 weeks, respectively. Table 4 Stratification according to preoperative knee extensor strength demonstrated a clear gradient in postoperative functional performance. Patients in the high-strength tertile achieved the shortest TUG times, greatest 6MWT distances, and lowest WOMAC scores at 12 weeks. Mean 12-week TUG time was 7.8 seconds in the high-strength group compared with 10.6 seconds in the low-strength group. Table 5 Preoperative knee extensor strength was associated not only with absolute postoperative functional performance but also with the magnitude of improvement during the first 12 weeks. Higher baseline strength demonstrated significant positive correlations with improvement in TUG time, 6MWT distance, WOMAC score, pain, and knee flexion. The associations were strongest for improvement in TUG and 6MWT performance. Table 6 Multivariable regression analysis demonstrated that preoperative knee extensor strength remained independently associated with 12-week TUG performance after adjustment for relevant demographic and clinical variables. Every 10 N increase in preoperative knee extensor strength was associated with an approximately 0.16-second reduction in 12-week TUG time after adjustment. Baseline TUG performance was another important independent predictor, while increasing age and BMI were associated with slower postoperative mobility. Table 7 Preoperative knee extensor strength also independently predicted walking capacity at 12 weeks. After adjustment for age, sex, BMI, baseline 6MWT performance, pain, and knee flexion, each 10 N increase in baseline knee extensor strength was associated with an approximately 8 m greater 6MWT distance at 12 weeks. Baseline walking capacity was independently associated with postoperative performance, whereas increasing age and BMI demonstrated significant negative associations.

The present prospective cohort study demonstrated a significant association between preoperative knee extensor strength and early functional recovery following primary total knee arthroplasty [1]. Patients with greater knee extensor strength before surgery achieved better postoperative mobility, greater walking capacity, and lower functional disability during the first 12 weeks following TKA [2]. The association was particularly evident for performance-based outcomes, with preoperative knee extensor strength demonstrating a moderate negative correlation with TUG time and a moderate positive correlation with 6MWT distance at 12 weeks. Importantly, these relationships remained significant after adjustment for age, sex, BMI, baseline functional performance, preoperative pain, and knee range of motion [3,4]. The study population represented patients typically undergoing TKA for advanced primary knee osteoarthritis, with a mean age of 65.1 years and predominance of women [5]. Patients demonstrated substantial preoperative impairment, including high pain intensity, restricted knee flexion, reduced walking capacity, and prolonged TUG performance [6]. Nearly one-third required a walking aid before surgery. These baseline findings indicate that patients were experiencing considerable limitations in mobility and activities of daily living at the time of arthroplasty [7]. The progressive improvement observed in TUG performance following surgery indicates substantial restoration of functional mobility during the first three postoperative months. Mean TUG time decreased from 16.2 seconds preoperatively to 11.3 seconds at 6 weeks and 9.2 seconds at 12 weeks [8]. This improvement reflects the combined effect of pain relief, restoration of joint mechanics, progressive weight bearing, rehabilitation, and recovery of lower-limb function. Nevertheless, postoperative performance varied considerably according to the level of preoperative knee extensor strength [9]. The strength-tertile analysis further demonstrated a clear gradient in recovery. Patients in the highest preoperative strength tertile recorded a mean 12-week TUG time of 7.8 seconds compared with 10.6 seconds in the lowest tertile [10]. Similarly, the high-strength group achieved a mean 6MWT distance of 455.8 m compared with 347.3 m in the low-strength group. The difference of more than 100 m between the extreme strength groups represents a substantial separation in functional walking performance [11]. This graded relationship supports the clinical relevance of preoperative muscular status rather than suggesting that the observed association resulted solely from a small subgroup of exceptionally weak patients [12]. An important finding was that baseline strength was related not only to absolute functional status at 12 weeks but also to the magnitude of improvement. Significant correlations were observed between preoperative strength and improvement in TUG, 6MWT, WOMAC, pain, and knee flexion [13]. However, these relationships were weaker than correlations with absolute postoperative performance [14]. This distinction suggests that stronger patients generally entered surgery at a better functional level and subsequently retained an advantage during recovery, while patients with lower baseline strength also experienced meaningful improvement after TKA [15]. The results additionally provide a rationale for preoperative conditioning or prehabilitation. However, the present study evaluated the prognostic association of baseline strength and was not designed to determine whether increasing strength before surgery would directly improve postoperative outcomes. Therefore, the observed relationship should not be interpreted as evidence that a specific preoperative strengthening programme will necessarily produce superior recovery. Interventional studies would be required to establish whether targeted improvement in knee extensor strength before TKA translates into clinically meaningful postoperative benefit. Strengths of the Study The prospective design enabled standardized assessment of patients before surgery and at predefined postoperative intervals. Objective measurement of knee extensor strength was combined with both performance-based and patient-reported functional outcomes. Repeated evaluation at 6 and 12 weeks permitted assessment of the early recovery trajectory rather than relying on a single postoperative measurement. The use of multivariable regression further enabled evaluation of the independent association of preoperative strength after accounting for important demographic and baseline clinical characteristics. Limitations The study was conducted at a single tertiary care hospital, which may limit generalizability to populations with different demographic, socioeconomic, or rehabilitation characteristics. Follow-up was restricted to 12 weeks and therefore represents early rather than long-term functional recovery. Knee extensor strength was measured using handheld dynamometry rather than isokinetic dynamometry; although clinically practical, measurements may be influenced by examiner stabilization and testing technique. Rehabilitation adherence outside the hospital could not be quantified with complete precision. Other factors potentially affecting recovery, including psychological status, physical activity level, muscle mass, nutritional status, and detailed contralateral knee function, were not incorporated into the multivariable models. Finally, as an observational cohort study, the demonstrated associations cannot establish that preoperative knee extensor weakness directly causes poorer postoperative functional performance. Clinical Implications Preoperative knee extensor strength appears to provide useful prognostic information regarding early mobility and walking capacity following TKA. Incorporating a standardized strength assessment into preoperative evaluation may help identify patients likely to experience slower early functional recovery. Such patients could be considered for individualized counselling, targeted muscle strengthening, and appropriately intensified perioperative rehabilitation. The findings also suggest that objective muscle assessment can complement conventional evaluation based on pain, radiographic severity, range of motion, and patient-reported disability when planning postoperative recovery.

Preoperative knee extensor strength demonstrated a significant association with early functional recovery following primary total knee arthroplasty. Patients with greater knee extensor strength before surgery achieved faster functional mobility, greater walking capacity, and better patient-reported functional outcomes during the first 12 postoperative weeks. The relationship was most pronounced for performance-based outcomes, particularly the Timed Up and Go test and 6-Minute Walk Test. Preoperative knee extensor strength remained independently associated with 12-week functional performance even after adjustment for age, sex, body mass index, baseline functional status, preoperative pain, and knee range of motion. These findings indicate that objective assessment of knee extensor strength can provide clinically useful information beyond conventional demographic and preoperative functional parameters. Routine preoperative measurement of knee extensor strength may therefore assist in identifying patients at risk of comparatively slower early functional recovery following TKA. Patients with substantial preoperative weakness may benefit from individualized counselling and greater emphasis on targeted quadriceps strengthening and structured rehabilitation. However, because the present study was observational, the association should not be interpreted as evidence that increasing preoperative strength alone will necessarily improve postoperative outcomes.

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