Dislocation of hemiarthroplasty after femoral neck fracture: better outcome after the anterolateral approach in a prospective cohort study on 739 consecutive hips.

BACKGROUND AND PURPOSE: Hip replacement using a hemiarthroplasty is a common surgical procedure in elderly patients with fractures of the femoral neck. The optimal surgical approach regarding the risk of dislocation is controversial. We analyzed factors influencing the stability of the hemiarthroplasty, with special regard to the surgical approach.

PATIENTS AND METHODS: We studied 720 consecutive patients on whom 739 hemiarthroplasties were performed between 1996 and 2003, either as a primary operation for a displaced fracture of the femoral neck or as a secondary procedure after failed internal fixation of a fracture of the femoral neck. Logistic regression analyses were performed in order to evaluate factors associated with prosthetic dislocation.

RESULTS: The multivariate regression analysis showed that the posterolateral approach was the only factor associated with a significantly increased risk of dislocation: OR 3.9 (CI: 1.6-10) for the posterolateral approach with posterior repair and OR 6.9 (CI: 2.6-19) for the posterolateral approach without posterior repair. Age, sex, indication for surgery, the surgeon's experience, and type of HA had no statistically significant effect on the dislocation rate.

INTERPRETATION: Compared to the anterolateral approach, the posterolateral approach was associated with a significantly increased risk of dislocation in patients with femoral neck fractures treated with HA. A posterior repair appears to reduce the rate of dislocation, although not to the same low level as in patients operated using the anterolateral approach.