Risk Factors for Early Dislocation Following Primary Elective Total Hip Arthroplasty

Dislocation following total hip arthroplasty (THA) continues to be one of the most common reasons for revision THA. The purpose of this study is to measure the current rate of dislocation following THA in the United States. A secondary goal is to identify patients at highest risk of instability after THA.

The Nationwide Readmissions Database was used to identify cases of elective primary THA between 2012 and 2014. All readmissions associated with dislocations were identified. Kaplan-Meier curves were used to assess the time to dislocation in the study population. A multivariate logistic regression was modeled to assess risk factors associated with readmission for dislocation.

A total of 207,285 THAs were identified between 2012 and 2014. Of the total, 2842 dislocation-associated readmissions (1.4%) were identified, at a median of 40 days post-THA. A history of spinal fusion was the strongest independent predictor of dislocation (odds ratio [OR], 2.45; 95% confidence interval [CI], 1.97-3.04; P < .0001). Parkinson's disease was also significantly associated with dislocation (OR, 1.63; 95% CI, 1.05-2.51; P = .03), as well as dementia (OR, 1.96; 95% CI, 1.13-3.39; P = .02), depression (OR, 1.28; 95% CI, 1.13-1.43; P < .0001), and chronic lung disease (OR, 1.2; 95% CI, 1.07-1.33; P = .001). Inflammatory arthritis and avascular necrosis were independent risk factors for dislocation (OR, 1.56; 95% CI, 1.25-1.97; P < .0001; OR, 1.67; 95% CI, 1.45-1.93; P < .0001).

THA is a highly effective procedure with a low overall rate of instability. A history of spinal fusion was the most significant independent risk factor for dislocation within the first 6 months following THA.