There have been few prospective studies comparing minimally invasive approaches for total hip replacement. We sought to ascertain the contribution of the minimally invasive posterior approach in comparison with the standard posterolateral approach in terms of early outcome.

This study investigated a prospective, comparative, consecutive series of patients. Patients with major architectural problems or undergoing revision arthroplasty were excluded. One hundred ten patients (116 hips) were divided into two groups that were comparable for the number of patients, gender, age, body mass index, indication for surgery, and preoperative function scores. The preoperative ASA score was lower in the minimally invasive group (p = 0.04). The patients were in the lateral reclining position for both approaches and classical instrumentation using the same implants (stems and cemented or noncemented cups) was used. We noted operative time and blood loss (using the Brecher method based on the hematocrit count at day 1 and 5 and the number of blood transfusions), postoperative pain, and implant position. Functional outcome was assessed with the modified Harris Hip Score and the WOMAC index (at 6 weeks and 3 and 6 months). Statview^® was used to search for statistical significance, considering p < 0.05 as significant.

The mean length of the incision was 8.5 cm versus 15.1 cm. The mean blood loss was significantly less in the minimally invasive group (p = 0.027), as was the level of postoperative pain as confirmed by the lower consumption of morphine analgesics (p = 0.006). Other operative variables as well as implant position were comparable. There were no major complications in the minimally invasive group. In the standard group, there was one case of common peroneal nerve palsy, two dislocations, and two fractures related to falls after prosthesis implantation. The WOMAC index score was higher after the minimally invasive approach at 6 weeks and at 3 months (p < 0.05). The modified Harris Hip Score was higher only at 6 weeks. Functional outcome and pain became comparable thereafter.

The minimally invasive posterior approach does not require an orthopedic table or specific instrumentation. A meticulous procedure is required with ligature of the posteromedial circumflex artery of the thigh to improve exposure and limit intraoperative bleeding. It enables satisfactory, reproducible implant positioning. Conversion to an open posterolateral approach is possible if needed. The minimally invasive posterior approach reduces intraoperative bleeding and postoperative pain with earlier and more rapid rehabilitation. The early clinical outcome is better, but beyond 6 weeks, the functional results are comparable for the two approaches. The minimally invasive posterior approach is a reliable, reproducible approach with a progressive learning curve.