Purpose: Hip dislocation after arthroplasty for femoral neck fractures (FNF) remains a serious complication. The aim of our study was to investigate FNF patients treated with THA, with a special focus of comparing the effect of surgical approach and femoral head size on the risk of revision for dislocation.
Methods: Data were derived from the Lithuanian Arthroplasty Register, and we calculated the cumulative revision rates after surgery. For survival analysis, we used revision due to dislocation as an end-point. Cox proportional hazards models were used to analyse the influence of various covariates (age, gender, femoral head size, surgical approach).
Results: A total of 8,813 primary THAs were registered from 1 January 2011 to 31 December 2013, of which 1,412 were due to FNF: 899 involved 28-mm femoral heads and the remaining 513 received 32-mm heads. The posterior approach was used in 1,156 cases and the anterolateral approach in 256.. At the end of the follow-up period, 74 hips had been revised for recurrent dislocation. Cox regression adjusting for age, gender and head size showed that the posterior approach had 2.3-times [95% confidence interval (CI): 1.0-5.0, p = 0.04] greater risk of revision for dislocation
Conclusions: We conclude that in order to reduce the early dislocation rate in FNF patients treated with THA, it is more effective to use the anterolateral approach than it is to select a femoral head size of 32 mm instead of 28 mm.