Outcomes of minimally invasive anterolateral THA are not superior to those of minimally invasive direct lateral and posterolateral THA.

backgroundThere has been considerable interest in minimally invasive surgical (MIS) THA in recent years. The MIS anterolateral approach, or the MIS Watson-Jones approach, is a novel intermuscular abductor-sparing technique. Early reports from case series suggest the potential for superior function and reduced complications; however, the available information from clinical reports is inadequate to suggest surgeons should change from their accepted standard approach. QUESTIONS/PURPOSES: We examined the potential superiority of this anterolateral approach, as judged by quality-of-life (QoL) measures, radiographic parameters, and complications, compared to limited-incision MIS direct lateral and MIS posterolateral approaches.

methodsWe performed a prospective randomized controlled trial involving five surgeons at three centers, recruiting 156 patients undergoing primary THA to receive either the MIS anterolateral or the surgeon's preferred approach (direct lateral or posterolateral). For the 135 patients we report, we collected patient-reported WOMAC, SF-36, Paper Adaptive Test in 5 Domains of Quality of Life in Arthritis Questionnaire [PAT5D], and patient satisfaction scores. We recorded complications and evaluated radiographs for prosthetic component position, subsidence, and fracture. Minimum followup was 24 months (mean, 30 months; range, 24-42 months).

resultsQoL and patient-reported satisfaction were similar between groups. Radiographic evaluation demonstrated no differences in acetabular component positioning; however, mean stem subsidence was 4.6 mm for the MIS anterolateral group and 4.1 mm for the alternate group, with differences observed among the three centers for stem subsidence and fracture. One center had increased rate of fracture requiring treatment and need for revision in the MIS anterolateral group.

conclusionsWe found no superiority of the MIS anterolateral approach but observed intersite differences in painful stem subsidence and fracture. We have returned to the standard surgical approaches in use before the trial. LEVEL OF EVIDENCE: Level I, therapeutic study. See Instructions for Authors for a complete description of levels of evidence.