Mini-midvastus total knee arthroplasty in patients with severe varus deformity.

Patients with severe varus deformity of the knee (≥15° varus) usually are not considered good candidates for minimally invasive total knee arthroplasty (TKA). The goal of this study was to retrospectively investigate outcomes in patients with severe varus deformity after minimally invasive TKA. A study group of 52 patients with a tibiofemoral mechanical axis of 195° or greater was compared with a matched control group of 55 patients with a tibiofemoral mechanical axis of less than 195°. Clinical and radiographic evaluations according to the American Knee Society rating system were obtained preoperatively and postoperatively, and postoperative patient satisfaction in the 2 groups was compared. All patients were followed at a mean of 3 years (range, 2-5 years). Preoperatively, clinical knee and function scores and range of motion were inferior in the study group compared with the control group (P<.001). However, at the latest follow-up, both groups of patients were satisfied with the clinical results, and no significant differences were found in the knee and function scores (P>.05). Radiographic evaluation showed no differences in the mechanical axis, femoral component valgus angle, and tibial component valgus angle, and all outliers of the radiographic parameters between the 2 groups postoperatively (P >.05). The study results showed that mini-midvastus TKA did not result in more inaccurate implant positioning in patients with severe varus deformity of the knee. The clinical outcome in the group with severe varus was comparable to that in the group with less severe varus