Flexion contracture following primary total knee arthroplasty: risk factors and outcomes

Function and satisfaction after total knee arthroplasty (TKA) are partially linked to postoperative range of motion (ROM). Fixed flexion contracture is a recognized complication of TKA that reduces ROM and is a source of morbidity for patients. This study aimed to identify preoperative risk factors for developing fixed flexion contracture following TKA and to quantify the effect of fixed flexion contracture on outcomes (Oxford knee score 12-60 and patient satisfaction) at 2 years. Pre-, intra-, and postoperative data for 811 TKAs were retrospectively reviewed. At 2 years postoperatively, the incidence of fixed flexion contracture was 3.6%. Men were 2.6 times more likely than women to have fixed flexion contracture (P=.012), and patients with preimplant fixed flexion contracture were 2.3 times more likely than those without to have fixed flexion contracture (P=.028). Increasing age was associated with an increased rate of fixed flexion contracture (P=.02). Body mass index was not a risk factor (P=.968). Incidence of fixed flexion contracture for those undergoing computer navigated TKA was 3.9% compared with 3.4% for those having conventional surgery (P=.711). Patients with fixed flexion contracture had poorer outcomes with a median [interquartile range] Oxford Knee Score of 25 [15] compared with 20 [11] for those without (P=.003) and lower patient satisfaction (P=.036). These results support existing literature for incidence of fixed flexion contracture after TKA, risk factors, and outcomes, indicating that these figures can be extrapolated to a wide population. They also clarify a previously contentious point by excluding body mass index as a risk factor.