FP6.8 Prolonged Use of Both Diclofenac and Indomethacin Has No Benefit for the Prevention of Heterotopic Ossification Following Hip Arthroscopy

Abstract ICLA06 - Finetuning FAI Surgery: Advanced Corrections and Avoiding Yatrogenic Instability, Auditorium A (BMCC Level 1), October 8, 2026, 14:00 - 16:00 Purpose This study compared the efficacy of diclofenac and indomethacin administered for different durations in preventing HO after hip arthroscopy and evaluated the impact of varying regimens on postoperative clinical outcomes. We hypothesized that both diclofenac and indomethacin would effectively prevent HO, with no significant difference in incidence of HO between them. Methods This retrospective, multicenter study included 1084 patients who underwent hip arthroscopy for femoroacetabular impingement between January 2017 and December 2024. Patients were categorized according to prophylaxis protocol: diclofenac 75 mg for 15 days and indomethacin 75 mg daily for 15, 30 and 45 days. HO presence and grade were assessed using the Brooker classification. Functional outcomes evaluated pre- and post- operatively using the Visual Analog Scale (VAS) for pain and the Hip Outcome Score–Activities of Daily Living (HOS-ADL). Results No significant difference in HO development was observed among groups (p=0.061), with an overall Grade 0 rate of 97.7%. The 45-day indomethacin regimen provided superior postoperative pain control with the mean postoperative pVAS score of 0.5 ± 0.4. In contrast, the 15-day diclofenac and indomethacin regimens achieved the greatest VAS improvement, with mean changes of 5.4 ± 1.6 and 6.8 ± 0.7, respectively. However, the highest postoperative HOS-ADL score was observed in the 15-day indomethacin group (90.4 ± 2.2), whereas the greatest HOS-ADL improvement was seen in the 30-day group (47.1 ± 3.9) followed by diclofenac (47.0 ± 3.8). Conclusion The greatest improvement in pain pVAS scores was achieved with the 15-day indomethacin and diclofenac regimens. For HOS-ADL, highest postoperative score was observed in 15-day indomethacin group, whereas the greatest improvement was recorded in the 30-day indomethacin and diclofenac regimens. These findings suggest that extending indomethacin prophylaxis beyond 30 days offers no additional clinical benefit. A shorter 15-day regimen may provide an effective and safe option for HO prevention following hip arthroscopy.