Predictors of Recurrent Flexion Contracture after Total Knee Arthroplasty in Osteoarthritic Knees with Greater Than 15° Flexion Contracture

BACKGROUND: This study aimed to analyze the risk factors that predict recurrent flexion contracture (FC) after total knee arthroplasty (TKA) in osteoarthritic knees with FC ≥ 15°. METHODS: Data from a consecutive cohort comprising 237 TKAs in 187 patients with degenerative osteoarthritis, preoperative FC ≥ 15°, and a minimum follow-up period of 2 years were retrospectively reviewed. Preoperative FC was corrected intraoperatively from 0° to 5°. The incidence of recurrent FC (FC ≥ 10°) at 2 years postoperatively was investigated. Potential risk factors predicting recurrent FC including age, sex, body mass index, unilateral TKA, severity of preoperative FC, 3-month postoperative residual FC, γ angle, change in posterior femoral offset ratio, and lumbar degenerative kyphosis (LDK) were analyzed using logistic regression analysis. The post-hoc powers for the identified factors were then determined. RESULTS: Forty-one knees (17.3%) with recurrent FC were identified. Risk factors with sufficient power for recurrent FC were unilateral TKA, severity of preoperative FC, residual FC at 3 months postoperatively, and LDK (odds ratios of 3.579, 1.115, 1.274, and 3.096, respectively; p < 0.05; power ≥ 86.1). CONCLUSIONS: Recurrent FC can occur in TKAs with the risk factors including unilateral TKA, severe preoperative FC, residual FC at 3 months postoperative, and LDK despite appropriate intraoperative correction. Surgical strategies and rehabilitation protocols used in managing FC should be applied in TKA cases with risk factors for recurrent FC.