Comparison of minimally invasive approach versus conventional anterolateral approach for total hip arthroplasty: a randomized controlled trial

It is a general belief among hip surgeons that minimally invasive surgical (MIS) approach for implantation of a total hip arthroplasty (THA) allows an improved and faster postoperative rehabilitation because of reduced muscle and soft-tissue damage, less postoperative pain and blood loss, and shorter hospital stay compared with conventional approaches. In the published relative literature though, there are controversial reports and debates on this matter. To our knowledge, there is no study on the medium-term functional results comparing MIS and traditional approaches for total hip replacement. The purpose of this prospective comparative controlled study was to compare MIS with conventional approach, on terms of pain, blood loss, and functional recovery over a follow-up period of 4 years.

In a total of 90 consecutive randomly selected adult patients, who suffered from unilateral primary hip osteoarthritis, a cementless Zweymüller-Plus THA (SL-Plus stem, Bicon screw socket) was implanted by a single senior orthopedic hip surgeon in one institution in the same period. Forty-five patients (group A) were operated using an MIS anterolateral, short incision, muscle-sparing approach and 45 (group B) with a conventional (anterolateral modified Watson-Jones) approach under partial detachment of gluteus medius and minimus. Anthropometric data, blood loss, short-form 36 questionnaire, visual analog scale pain score, and walking endurance were included in the analysis. Approach-related surgical complications (trochanter major fracture, Bicon malposition) were recorded. Data were collected postoperatively and at 4-year follow-up.

Two patients of group A and eight patients of group B were excluded from the final analysis. Thus, 80 patients were eligible for the final evaluation 4 years postoperatively. Postoperative pain score was less in the MIS group. However, no differences in perioperative blood loss, functional outcome, and walking endurance were shown between groups. No difference in Bicon cup implantation angle was measured in postoperative roentgenograms between group A and B patients, no intraoperative trochanter fracture occurred in any patient of both groups.

The present prospective randomized study revealed no significant mid-term clinical and functional benefit for patients who underwent a THA through an MIS in comparison with those who were managed with a conventional open approach.