Outcomes of heterotopic ossification excision following revision hip arthroscopy

This study reviewed pain and outcome scores of patients undergoing revision surgery with heterotopic ossification (HO) excision following previous hip arthroscopy. The aim was to determine if performing the excision arthroscopically improved clinical outcomes. Data were prospectively collected and retrospectively reviewed in patients who had HO removed arthroscopically between February 2008 and 2014. Four patient-reported outcome (PRO) measures were collected: Modified Harris Hip Score (mHHS), Non-Arthritis Hip Score (NAHS), Hip Outcome Score-Activity of Daily Living (HOS-ADL) and Sport-Specific (HOS-SS) subscales. Minimum 1.5 year follow-up from index procedure was available for 23 patients (mean age = 38.6 years). Of the 23 patients who had revision surgery and HO removal, 19 (83%) were available for follow-up. Prior to revision, the average mHHS was 53.4, HOS-ADL 51.4, HOS-SS 24.5, NAHS 50.3 and VAS 6.7. Following revision with HO excision, each score had improved with an average mHHS of 73.62, HOS-ADL of 68.88, HOS SS of 58.51, NAHS of 70.83 and VAS of 4.33. Overall, mHHS increased by 20.26 points (P < 0.001), HOS-ADL increased by 17.48 points (P = 0.023), HOS-SS increased by 34.03 points (P < 0.001), NAHS increased by 20.55 points (P = 0.001) and VAS decreased by 2.38 points (P < 0.001). Patients undergoing revision hip surgery with HO excision demonstrated improved outcome scores and pain resolution; however, few patients achieved a good or excellent result. Revision hip surgery with HO excision should be approached cautiously because of the modest results in this patient group.