Evaluation Of The Risk Factors Associated With Dislocation Following Cementless Bipolar Hemiarthroplasty Of The Hip In Elderly Patients: A Nested Case-Control Study

Introduction: Although a well-known advantage of the cementless fixation technique is that it prevents bone cement implantation syndrome, with lower perioperative mortality, the risk factors associated with dislocation after cementless bipolar hemiarthroplasty (BHA) have not yet been sufficiently investigated. This study aimed to investigate the incidence of dislocation following cementless BHA of the hip in elderly patients with displaced femoral neck fractures. The related risk factors are also examined.Methods: In this nested case-control study, patients who had undergone BHA for femoral neck fracture at a single tertiary referral center were retrospectively reviewed. Three control patients from the cohort who had not experienced dislocation were selected for each patient who developed dislocation following BHA. Clinical and radiographic outcome measures were then assessed to determine the risk factors for dislocation following BHA.Results: Of the 103 patients available for the analyses in the current study, 23 patients (12 females, 11 males) with dislocation were selected as the study group and 70 patients (33 females, 37 males) without dislocation were included in the control group. Univariate analyses revealed significant differences between the two groups in terms of number of postoperative surgical site infections, dementia, center-edge angle, and femoral offset. Two independent risk factors associated with dislocation, namely, infection and dementia, were identified during multivariate model analysis.Conclusion: Patients with postoperative surgical site infection or dementia are at greater risk for developing dislocation after cementless BHA.