Residual Mild Varus Alignment and Neutral Mechanical Alignment Have Similar Outcome after Total Knee Arthroplasty for Varus Osteoarthritis in Five-Year Follow-Up

摘要

The effect of residual varus on survival rate and function in patients with varus knee osteoarthritis (OA) was considered an important issue for successful primary total knee arthroplasty (TKA). In this study, we compared the midterm clinical and functional outcomes in patients with different residual varus. A retrospective review of 175 patients (219 knees) with varus OA was > 3 degrees for the hip-knee-ankle (HKA) who underwent primary TKA after exclusions and loss to follow-up from 237 patients (281 knees). The mean follow-up period was 5.2 ( +/- 1.1) years. Patients were divided into four groups according to the first postoperative HKA angle from weight-bearing full-leg radiographs: "valgus" group (HKA angle > 0 degrees, n = 44), "neutral" group (-3 degrees 0.05). WOMAC scores of the neutral and mild varus groups were also better compared with the valgus and severe varus groups ( p < 0.05), and there were no significant differences between the neutral and mild varus groups at the last follow-up. The postoperative HKA angle was significantly changed in valgus group between first and at the last follow-up when compared with the other three groups ( p < 0.05). Leaving an HKA angle at < 6 degrees varus had the same excellent functional outcome as neutral mechanical alignment after TKA for varus-type OA in the 5-year follow-up, using mechanically aligned technique. Caution is advised when leaving valgus or leaving severe varus after TKA.