Changes in Hip Arthroplasty Practice Decreased Dislocation Risk After Primary Arthroplasties Performed for Nontraumatic Osteonecrosis of the Femoral Head.

BACKGROUND

Hip arthroplasty practices have evolved considerably over time. This nationwide multicenter follow-up cohort study of primary hip arthroplasties performed for nontraumatic osteonecrosis of the femoral head aimed to address the following question: Have demographic and operative variables, as well as follow-up outcomes (dislocation and need for reoperation), changed over time?

METHODS

A total of 7,494 hip arthroplasties were analyzed, categorized into three 9-year periods based on the date of operation: the first (1996 to 2004, 1,403 hips), the second (2005 to 2013, 2,631 hips), and the third (2014 to 2022, 3,460 hips) periods.

RESULTS

Demographic characteristics changed gradually over time, while operative variables shifted significantly. The use of the posterior approach declined, and larger prosthetic heads became more common. The overall dislocation rate was 4.1% (307 hips) and varied by surgery type: 4.7% in total hip arthroplasties, 1.1% in bipolar hemiarthroplasties, and 0% in resurfacings (Chi-square test; P < 0.001). Factors associated with dislocation were analyzed in 6,207 total arthroplasties (6,026 total hip arthroplasties and 181 total resurfacings) with a mean follow-up of 7.1 years (range, 0.5 to 27). The dislocation rate was 4.7%, with rates of 10.5, 5.4, and 2.3% in the first, second, and third periods, respectively (Chi-square test; P < 0.001). Multivariate logistic regression confirmed the reduction in dislocation risk over time; compared with the second period, odds ratios for the first and third periods were 1.48 (P = 0.015) and 0.58 (P = 0.001), respectively. No significant temporal changes in the risk of reoperation were observed.

CONCLUSIONS

With temporal transition, demographic characteristics evolved gradually, while operative techniques changed markedly. The decline in the use of the posterior approach and the increased adoption of larger prosthetic heads likely contributed to the observed reduction in dislocation risk. However, the risk of reoperation remained unchanged across periods.