Minimally Invasive versus Classic Procedures in Total Hip Arthroplasty: A Double-blind Randomized Controlled Trial

BACKGROUND: For total hip arthroplasty (THA), minimally invasive surgery (MIS) uses a smaller incision and less muscle dissection than the classic approach (CLASS), and may lead to faster rehabilitation. QUESTIONS/PURPOSES: Does minimally invasive hip arthroplasty result in superior clinical outcomes? PATIENTS AND METHODS: In this double-blind randomized controlled trial, 120 consecutive primary noncemented THAs in 120 patients were assigned to one of two groups (MIS or CLASS). The randomization sequence was stratified for two groups of surgeons, ie, those using a posterolateral approach (PL-CLASS or PL-MIS) and those using an anterolateral approach (AL-CLASS or AL-MIS). Length of the incisions was 18 cm for the CLASS procedures. MIS incisions were extended at the skin level to 18 cm at the end of the procedure. The primary end point was the Harris hip score (HHS) at 6 weeks postoperatively. Patient-centered questionnaires were obtained preoperatively and after 6 weeks and 1 year. RESULTS: For the patients in the MIS group (average 7.8 cm incision length), statistically significant increased mean HHSs were seen compared with the CLASS group at 6 weeks and 1 year. This difference was small and mainly caused by the favorable results of the PL-MIS. In the MIS group, surgical time was longer. A learning curve was observed based on operation time and complication rate. Although not statistically significant, the perioperative complication rate was rather high in the (anterolateral) MIS group. CONCLUSIONS: The minimal invasive approach in THA did not show a clinically relevant superior outcome in the first postoperative year. LEVEL OF EVIDENCE: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.