Early Quadriceps Recovery and Edema Reduction Predict Functional Performance After Total Knee Arthroplasty

Total knee arthroplasty (TKA) is an effective intervention that alleviates pain and restores joint function in patients with advanced knee osteoarthritis. However, persistent quadriceps muscle weakness often limits early functional recovery, and the contribution of early postoperative changes in muscle strength, edema, and pain to short-term function remains unclear. The aim of the study was to investigate early postoperative changes in quadriceps strength, edema, and pain, and their relationships with functional performance at 6 weeks after unilateral TKA. A total of 24 patients (mean age: 68.67 years; body mass index: 33.18 kg/m²; 20 females, 4 males) undergoing primary unilateral TKA were assessed on postoperative day 1, week 2, and week 6. Outcome measures included isometric quadriceps strength, knee edema, pain intensity (VAS), and functional performance (5 times sit-to-stand test [5T-Stst], 2-minute walk test [2MWt], WOMAC). Correlations and forward stepwise multiple regression analyses evaluated the predictive value of early recovery indicators on functional outcomes. Significant improvements in quadriceps strength and reductions in edema and pain were observed within 6 weeks. Early quadriceps strength gains (day 1 to week 2) were strongly associated with faster 5T-Stst performance at week 6 (r = -0.644, p = 0.001), accounting for 27% of its variance (R² = 0.27, p = 0.005). Edema reduction also correlated with improved sit-to-stand performance (r = 0.528, p = 0.008), whereas early pain reduction showed no significant correlation with functional outcomes. Early postoperative improvements in quadriceps muscle strength and edema resolution are critical predictors of short-term functional recovery after TKA, whereas pain relief alone is insufficient. These findings emphasize the first 2 postoperative weeks as a pivotal window for rehabilitation interventions focusing on neuromuscular activation and swelling control. Objective assessment of quadriceps strength from the first postoperative day may guide personalized rehabilitation strategies and optimize recovery strategies.