Does Prior Lumbar Fusion Influence Dislocation Risk in Hip Arthroplasty Performed for Femoral Neck Fracture

INTRODUCTION Immobility of the lumbar spine predicts of instability following elective total hip arthroplasty (THA). The purpose of this study was to determine how prior lumbar fusion (LF) influenced dislocation rates and revision rates for patients undergoing THA or hemiarthroplasty (HA) for femoral neck fracture (FNF). METHODS A retrospective cohort analysis was conducted utilizing the PearlDiver Database from 2010-2018. Patients who underwent arthroplasty for FNF were identified based upon history of LF and whether they underwent THA or HA. Univariate and multivariate analyses were performed. RESULTS A total of 328 patients with prior LF and FNF who underwent THA were at increased risk for 1-year dislocation (OR=2.19; p<0.001) and 2-year revision (OR=2.22; p<0.001) compared to 14,217 patients without LF. The 461 patients with prior LF and FNF who underwent HA were at increased risk for dislocation (OR=2.22; p<0.001) compared to 42,327 patients without LF. Patients with prior LF and FNF who underwent THA had higher rates of revision than patients with prior LF who underwent HA for FNF (OR=2.11; p<0.001). In patients with prior LF and FNF, THA was associated with significantly increased risk for dislocation (OR=3.07; p<0.001) and revision (OR=2.53; p<0.001) compared to THA performed for osteoarthritis. DISCUSSION Patients with prior LF who sustained a FNF and underwent THA or HA were at increased risk for early dislocation and revision compared to those without prior LF. This risk of dislocation and revision is even greater than that observed in patients with prior LF who underwent THA for OA.