Heterotopic ossification following total hip arthroplasty. Which is the predominant risk factor: surgical approach or post-operative prophylaxis?

Purpose

To investigate the impact of surgical approach and post-operative prophylaxis on heterotopic ossification (HO) development after total hip arthroplasty (THA).

Methods

A retrospective analysis of 312 patients who underwent THA between January 2009 and April 2016. Patients were categorized by surgical approach (direct lateral or posterolateral), prosthesis type, and post-operative prophylaxis (Etoricoxib 60 mg daily for two weeks). Two orthopaedic surgeons independently assessed radiographs at serial intervals, and HO was graded as per Brooker classification. Bivariate analysis and regression modelling were performed to assess the associations and confounding effects of different variables,

Results

Bivariate analysis identified factors correlated with higher HO incidence: absence of prophylaxis, older age, longer symptom evolution, and lower pre-surgery physical activity. Regression modelling showed a correlation between the direct-lateral approach, post-operative prophylaxis, symptom evolution, and higher HO incidence.

Conclusion

Patients with longer symptom evolution before surgery and without post-operative prophylaxis are at higher risk of developing HO. While the direct lateral approach showed higher HO rates, the difference was insignificant. A two-week prophylactic regimen of Etoricoxib 60 mg daily after THA effectively reduced HO formation. Pharmacological prophylaxis should be evaluated case-by-case, considering patient characteristics and risk factors.