Abductor Insufficiency After Total Hip Arthroplasty; Risk Factors and Diagnosis

The use of lateral approach has been empirically associated with increased risk of abductor insufficiency and limping after total hip arthroplasty compared with the posterior approach. However lateral approach remains a widespread technik because it provides a decreased risk of dislocation. In litterature, gluteus medius insufficiency has been reported even when the posterior approach has been used. In the early stage of postperative relhabilitation it is difficult to distinguish between between limping that resolves after abductor training and limping due to abductor injury/avulsion that is resistent to physiotherapy. The purpose of this randomized controlled trial is to compare the risk of persistent limping one year after total hip arthtoplasty between lateral and posterior approach and to identify patient-related risk factors for limping. Moreover it will validate ultra sound (U/S), magnetic resonance imaging (MRI) of the hip and gait analysis as diagnostic tools for early detection of limping that is going to persist one year after total hip arthroplasty.

580 patients will hip osteoarthritis be randomised to receive their total hip arthroplasty through an either lateral of posterior approach and will be followed at one year with physical examination (Trendelenburg sign) and patient.-reported outcome measures. Patients with a positive Trendelenburg sign at 3 months will undergo U/S and MRI examination as well as gait analysis and reassessed at one year with physical examination. The first 40 patients with negative Trendelenburg sign at 3 months will also undergo U/S, MRI and gait analysis. The specificity and sensitivity of U/S, MRI and gait analysis for positiv Trendelenburg sign will be calculated.