Heterotopic ossification (HO) is a well-known complication after total hip arthroplasty (THA). The origin and pathogenesis of HO are still unknown. The incidence of HO without sufficient prophylaxis varies from 8 to 90% after THA depending on the individual risk profile [
1]. Up to 15% of all HO become symptomatic by causing pain and limited range of motion of the affected joint [
2,
3]. In 2000, Eggli et al. [
4] studied the effect of HO on the satisfaction rate of patients. They showed that severe HO after THA decreases the satisfaction rate to 30% compared to 90% for patients without HO. Low-dose radiation therapy [
5] and non-steroidal anti-inflammatory drugs (NSAID) [
1] have proven to effectively reduce the rate of HO after THA. However, the use of NSAIDs shows side effects such as gastrointestinal problems, prolonged bleeding time, and an increase of associated fractures [
6]. In several studies up to 37% of patients receiving NSAID had to cease this medication due to undesirable side effects [
7]. Selective cyclooxygenase (COX)-II blockers have a lower rate of gastrointestinal bleeding compared to classical NSAIDs and seem to be a reasonable alternative for oral prophylaxis with respect to contraindications like for example cardiovascular disorders [
8]. Celecoxib, rofecoxib (withdrawn from the market), and etoricoxib have proven to reduce HO after primary THA [
8‐
11]. The study of Winkler et al. [
12] shows an equal efficiency of etoricoxib (90 mg once daily for nine days postoperative) compared to diclofenac (75 mg twice daily for nine days postoperatively) in preventing HO after primary cementless THA. Up to now, there are only two studies published concerning etoricoxib [
11,
12], each with a small sample size (42 respectively 47 patients) and a limited follow-up time of 6 months. In the comment regarding the publication of Brunnekreef et al. [
11], Zhang et al. [
13] recommended a longer follow-up time of at least 1 year, a larger sample size, and special attention to adverse effects of etoricoxib. Winkler et al. [
12] described 12.9% adverse events in the etoricoxib group related to the study medication compared to 9.4% in the diclofenac group. The most frequent adverse events in both groups were nausea, vomiting, dizziness, and diarrhea [
12].