Comparison of functional recovery and complications between varus and valgus knees after total knee arthroplasty: a large-sample cohort study

Objective To compare functional recovery, pain patterns, analgesic requirements, and postoperative complications between patients with varus and valgus deformities who underwent primary total knee arthroplasty (TKA), and to evaluate the clinical impact of lower limb alignment on prognosis. Methods A retrospective analysis was conducted on 1,547 patients who underwent primary TKA for knee osteoarthritis or rheumatoid arthritis at the Department of Joint Orthopedics, People’s Hospital of Ningxia Hui Autonomous Region, between January 2020 and December 2023. Patients were divided according to the preoperative hip-knee-ankle (HKA) angle into the varus group (HKA < -3°, n = 1,356) and the valgus group (HKA > 3°, n = 191). Baseline characteristics, surgical data, and follow-up outcomes were collected, including Hospital for Special Surgery (HSS) knee score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Forgotten Joint Score (FJS-12). Complications, revision rates, patient satisfaction, and analgesic use were also recorded. Results No significant differences were observed between the two groups in age, follow-up duration, BMI, WOMAC, or FJS-12 scores ( P > 0.05, d < 0.2). The valgus group had significantly higher ASA scores (2.30 vs. 2.17, P < 0.001, d = 0.33) and longer symptom duration (9.52 vs. 8.12 years, P < 0.001, d = 0.49), but significantly lower postoperative HSS scores (75.96 vs. 84.20, P < 0.001, d = 0.78). Univariable analysis revealed that the valgus group had higher rates of dissatisfaction (16.8% vs. 7.5%, P < 0.001, φ = 0.108) and persistent pain (34.0% vs. 18.9%, P < 0.001, φ = 0.123), whereas revision rates did not differ significantly (1.57% vs. 0.59%, P = 0.131, φ = 0.038). Stratified analysis revealed a significant interaction between deformity type and disease type (Breslow-Day P < 0.001). In OA patients, valgus deformity was associated with a markedly higher risk of dissatisfaction (OR = 11.05, 95% CI 5.92–20.58, P < 0.001). In RA patients, no significant difference was observed (OR = 0.63, 95% CI 0.23–1.69, P = 0.350). Daily analgesic use was significantly more frequent in the valgus group (38.5% vs. 15.6%, OR = 3.38, P < 0.001, φ = 0.228). Conclusion The effect of valgus deformity on postoperative satisfaction depends on disease type. In OA patients, valgus deformity significantly increases the risk of dissatisfaction; in RA patients, no significant difference is observed between valgus and varus groups. RA itself was associated with a higher overall dissatisfaction rate.Valgus deformity is also associated with a distinctive walking-pain phenotype and higher analgesic dependence, but revision rates were not significantly different. Clinical decision-making should stratify by disease type rather than relying on coronal alignment alone.