SPARING OF GLUTEUS MEDIUS IN A MODIFIED ANTEROLATERAL APPROACH TO HIP ARTHROPLASTY

Abstract

Introduction: The anterior and anterolateral approach to the hip traditionally are well described exposures in primary hip arthroplasty with fewer dislocations than the posterior approach. A very debilitating complication associated with the anterolateral approach however is the persistent limp and positive Trendelenburg sign. We discuss our results with respect to abductor function and morphological integrity seen on MRI when using an approach in which we preserve the majority of gluteus medius.

Methods: We carried out a prospective study of thirty-nine consecutive total hip replacements performed through a gluteus medius sparing anterolateral approach. The same hip surgeon performed all these between April and October 2004. Gait analysis and Trendelenburg tests were evaluated during clinical follow-up at six weeks and three months. Coronal STIR and T1 weighted MRI sequences of the abductors were performed between four and six weeks and the findings were agreed by the consensus of two radiologists.

Results: At three-month follow-up all thirty-nine patients tested Trendelenburg negative. Post-operative radiographs showed satisfactory femoral and acetabular component position. MRI findings showed the gluteus medius tendon to be intact with no shortening on T1. Artefacts were found to be less marked in the higher field strength magnet but more apparent in the STIR weighted sequences.

Discussion: We have tried to incorporate the advantages of reduced dislocation rate of the anterolateral approach, whilst avoiding violation of the abductors. The clinical result and radiographic findings we have presented suggest that the described exposure is an effective and safe method of approaching the hip, with minimal disruption of the abductor mechanism. In addition to maintaining the reduced dislocation rate associated with the standard anterolateral approach. Intact abductor function allows for rapid rehabilitation.