No Added Benefit of Nonsteroidal Anti-Inflammatory Drug Prophylaxis Beyond 15 Days for Heterotopic Ossification After Hip Arthroscopy.

BACKGROUND: Heterotopic ossification (HO) is a well-known postoperative complication of hip arthroscopy that can lead to pain, limited range of motion, and, in advanced cases, the need for revision surgery. Nonsteroidal anti-inflammatory drugs (NSAIDs), including diclofenac and indomethacin, are widely used for HO prophylaxis. However, there is no consensus on the optimal agent, dosage, and duration of administration. HYPOTHESIS/PURPOSE: This study aims to compare the efficacy of diclofenac and indomethacin administered for different durations in preventing HO after hip arthroscopy and to evaluate the impact of varying treatment regimens on postoperative clinical outcomes. It was hypothesized that both diclofenac and indomethacin would effectively prevent HO, with no significant difference in HO incidence between them or with prolonged treatment. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective, multicenter study included 1084 patients who underwent hip arthroscopy for femoroacetabular impingement (FAI) between January 2017 and December 2024. Patients were categorized according to the prophylaxis protocol administered: diclofenac 75 mg for 15 days or indomethacin 75 mg for 15, 30, or 45 days daily. The presence and grade of HO were evaluated according to the Brooker classification. Functional outcomes were assessed pre- and 3, 6, 9, and 12 months postoperatively using the visual analog scale for pain (VAS-Pain) and the Hip Outcome Score-Activities of Daily Living (HOS-ADL). RESULTS: No significant difference in HO development was observed among the study groups (P = .061), with an overall grade 0 rate of 97.7%. The 45-day indomethacin regimen provided superior postoperative pain control with the mean postoperative VAS-Pain score of 0.5 ± 0.4. In contrast, the 15-day diclofenac and indomethacin regimens achieved the greatest improvement, with mean differences in VAS-Pain scores 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 improvement in HOS-ADL was observed in the 30-day group (47.1 ± 3.9), followed by the diclofenac regimen (47 ± 3.8). CONCLUSION: The incidence and severity of HO did not differ significantly among diclofenac and indomethacin prophylaxis regimens after hip arthroscopy. Prolonging indomethacin prophylaxis beyond 15 days was not associated with a lower rate of HO. These findings suggest that longer NSAID prophylaxis protocols may not provide additional benefit for HO prevention compared with shorter regimens.