Dislocation after hemiarthroplasty of the hip: a comparison of the dislocation rate after posterior and lateral approaches to the hip.

We compared the 3-month dislocation rate for hip hemiarthroplasties inserted via the posterior and direct lateral routes. In all, 2906 primary hemiarthroplasties, performed between 1986 and 1992 in four hospitals on a training hospital rotation, were analysed. The posterior approach was used in 1656 (57%) and the lateral in 1250 (43%). The groups were otherwise comparable. The overall dislocation rate for the posterior approach was 9.0% (149/1656), whereas that for the direct lateral approach was 3.3% (41/2150). The difference is statistically highly significant. In addition, we analysed the dislocation rate for each approach in the three broad groups of surgical trainee. For senior registrars, there was no statistical difference in the dislocation rate. However, for registrars and senior house officers, there were statistically highly significant differences in the dislocation rate for posterior and direct lateral approaches (8.4% vs 3.3% and 14.2% vs 3.6%, respectively). We conclude that, because of the high mortality associated with dislocation of a hemiarthroplasty, the posterior approach for this operation should now be abandoned, especially by surgical trainees early in their careers.