Is the number of dislocations after bipolar hemiarthroplasty affected by anatomical parameters?

Abstract

The aim of this study was to evaluate the relationship between the number of dislocations and anatomical parameters after bipolar hemiarthroplasty (BHA) in femoral neck fracture (FNF) treatment. ‘A total of 240 consecutive patients (157 females, 83 males) with FNFs who were treated with BHA were evaluated retrospectively. Of these 24 patients with dislocations divided into two main groups according to the number of dislocations: Single-dislocation (Group 1, n=15) and multiple-dislocation groups (Group 2, n=9). Surgery-related and anatomical morphologic features as well as patient factors and clinical outcomes were comparatively analyzed between the groups. Pre and postoperative standard anteroposterior (AP) and lateral radiographs were used to evaluate for surgical and anatomical parameters. Harris and Modified Harris Scores were used to evaluate postoperative clinical outcomes. The mean follow-up period was 30.2±11.7 months (range, 12-56 months). Mean age was 80.1±6.4 years (range, 71-98 years). Dislocation incidence was 10.0% (24/240). Mean time to first dislocation was 2.3±1.4 months (range, 1-6 months). Mean number of dislocations was 2.1±1.0 (range, 1-4). There was significant difference in surgical factors and anatomical parameters between groups including nonoperated side offset (ON), nonoperated side femoral offset (FO), residual femoral neck length (RFNL), major trochanter upper end and femoral head center distance (TEFHCD) of nonoperated side, height of hip center (HHC) of operated and nonoperated side, femoral neck-shaft angle (FNSA) of operated side and pelvic obliqity (PO) between the groups (p0.05). Surgery-related and anatomical morphologic features were found to be effective in the number of dislocations (re-dislocation) after BHA. Patients who experienced the first-time dislocation after BHA with anatomical and surgical risk factors should be carefully monitored and more controlled physiotherapy may be recommended in terms of re-dislocation risk.