Clinical Outcomes of Patients with Heterotopic Ossification Following Hip Arthroscopy for Femoro-acetabular Impingement and Labral Tears

Background: The clinical manifestations of heterotopic ossifications (HO) after hip arthroscopy are difficult to isolate from other sources of post-operative pain.

Purpose: To assess clinical outcomes in patients who developed HO following hip arthroscopy surgery compared to controls without HO formation.

Methods: A retrospective analysis of prospectively collected data was performed. Patients who underwent arthroscopic hip surgery for FAI or labral tear with radiographic follow-up of more than 9 weeks were reviewed. Demographic data, intraoperative findings, as well as preoperative and post-operative modified Harris Hip Score (MHHS) and Hip Outcome Score (HOS) and overall satisfaction were evaluated.

Results: The HO group consisted of 26 patients with a mean age 36.3 years (range 18-65). The control group consisted of 43 patients with a mean age 35.6 years (range 19-68). Age was not significantly different between groups (p=.837) as well as gender distribution (18 M : 8 F in the HO group; 26 M: 17 F in the control group; p=.463). No significant differences were found in pre-operative MHHS scores, post-operative and MHHS improvement between the groups (66.7 vs. 60.8 p=.218, 81.1 vs. 80.4 p=.894, 17.3 vs. 18.9 p=.792, respectively. No significant differences were found between the groups in mean pre-operative, post-operative, and mean improvement in HOS scores (69.6 vs. 62.3 p=.210, 81.8 vs. 83.7 p=.702, 10.7 vs. 17.9 p=.083, respectively). Further stratification analysis of the results was performed according to the Brooker classification. No Statistically significant differences were evident between the different Brooker grades and the control group and within the Brooker grades in terms of pre-operative, pos-toperative and improvement of MHHS and HOS scores. Overall satisfaction rating in the HO group was 89.7% and the control group reported a mean satisfaction rating of 82.6%.

Conclusion: Heterotopic ossification formation following hip arthroscopy does not seem to significantly alter clinical outcomes and overall satisfaction ratings, regardless of the grade of HO formation.