PROSPECTIVE AND COMPARATIVE STUDY OF THE ANTEROLATERAL MINI-INVASIVE APPROACH VERSUS MINIMALLY INVASIVE POSTERIOR APPROACH FOR PRIMARY TOTAL HIP REPLACEMENT. EARLY RESULTS

Abstract

Introduction: The minimally invasive posterior approach has become a standard for total hip replacement (THR) but the interest for the other minimally invasive approaches has not waned in any way. We carried out a prospective and comparative study in order to analyse the interest of the anterolateral minimal invasive (ALMI) approach in comparaison to a minimally invasive posterior (MIP) approach for THR.

Material and method: We carried out a prospective and comparative study. A group of 35 primaries THR with large head using the ALMI approach, as described by Bertin and Röttinger, was compared to a group of 43 primaries THR performed through the MIP approach. The groups were not significantly different with respect to age, sex, bony mass index, ASA score, Charnley class, diagnoses and preoperative Womac index and PMA score. The preoperative Harris hip score was significantly lower in ALMI group. Early functional results have been evaluated thanks to Womac index and modified Harris hip score at 6 weeks, 3 and 6 months. A p value < 0.05 has been considered as significant.

Results: The duration of surgical procedure was longer and the calculated blood loss more important in ALMI group (respectively p=0.045 and p=0.07). The preoperative complications were significantly more frequent in this group with 4 greater trochanter fractures, 3 false routes, 1 calcar fracture, and 2 metal back bascules versus one femoral fracture in MIP group. Other postoperative data (implant positioning, morphine consumption, length of hospital stay, type of discharge) were comparable. The early functional results at 6 weeks, 3 and 6 months were also comparable. No other complication has been noted during the first 6 months in the two groups.

Discussion and Conclusion: The ALMI approach uses the intermuscular interval between the tensor fascia lata and the gluteus medius. It leaves intact the abductors muscles and the posterior capsule and short external rotators. The early clinical results are excellent despite of the initial complications related to the initial learning curve for this approach and the use of the large head with metal-on-metal bearing. The stability of the arthroplasty and the absence of muscular damage should permit to accelerate the postoperative rehabilitation in parallel with less preoperative complications after the initial learning curve.