Hip Arthroscopy and Heterotopic Ossification: Is NSAID Prophylaxis Justified? Commentary on an article by James T. Beckmann, MD, MS, et al.: "Effect of Naproxen Prophylaxis on Heterotopic Ossification Following Hip Arthroscopy: A Double-Blind Randomized Placebo-Controlled Trial".

Abstract

Heterotopic ossification (HO) is a process in which unwanted and potentially disabling bone tissue forms in abnormal locations such as muscles, musculotendinous junctions, and joint capsules. It may occur after trauma and after surgery. It is well known around the elbow and hip following fracture surgery and total hip replacement. The number of hip arthroscopies performed has increased exponentially over the last decade, and HO has become well recognized following this mini-invasive procedure. Although not as commonly experienced as a clinical problem, it is frequently demonstrated on postoperative radiographs. It is therefore of interest to investigate whether this abnormal bone formation can be reduced in a controlled study. Nonsteroidal antiinflammatory drugs (NSAIDs) have been used to prevent HO for years in other settings and are also commonly used following hip arthroscopy. However, NSAIDs may also cause serious complications, and knowledge about the effect and risk in each specific indication is important. The article by Beckmann et al. addressed this problem in a well-conducted double-blind randomized controlled trial (RCT) in which three weeks of treatment with 500 mg of naproxen twice daily was compared with a placebo. They found a remarkable difference between the NSAID group and the placebo group with regard to radiographic findings of HO (documented in 4% and 46% of the patients, respectively). Medication compliance was 69% overall, and minor adverse events were reported in 42% in the treatment group and 35% in the control group. Only one patient developed symptomatic HO that required revision surgery. Unfortunately, few RCTs have been performed in orthopaedics, including the quickly evolving field of hip arthroscopy. New techniques have been developed and implemented without full knowledge of the benefit for the patients and how to select the right treatment for the right patient. In a PubMed search for “hip arthroscopy,” 801 studies were found, but when the search was limited to RCTs there were eight (and all were not actually RCTs). However, there is promising research under way: RCTs on the general efficacy of hip arthroscopy are ongoing. The study by Beckmann et al. is an important and welcomed contribution to this so far limited number of Level-I hip arthroscopy studies. NSAIDsmay affect tissue healing. Healing of soft tissue (such as a tendon) to bone has been shown to be impaired byNSAIDs in experimental studies. A negative effect of NSAIDs on the healing of the sutured labrum or capsule in hip arthroscopy may therefore be an issue. NSAIDs have potential serious side effects, and although Beckmann et al. did not report serious or fatal complications in their study of 108 patients, they may occur sooner or later in a larger patient population. Clinically relevant HO is uncommon, and this has to be weighed against the risk of serious side effects caused by NSAIDs. Another question is whether the HO is a temporary phenomenon. A follow-up study of this patient cohort would be of great interest to see to what extent the HO develops further, is reduced, or disappears. This well-performed double-blind RCT documents that NSAIDs can reduce the frequency of radiographic evidence of HO following hip arthroscopy to a minimum. However, the clinical benefit and potential harm of routine NSAID prophylaxis are still unknown. As the authors point out, the lowest dose and shortest duration of NSAID prophylaxis that still prevent HO remain to be determined. This important study raises new questions, and there are many possible directions for further research in this field. Sverre Loken, MD, PhD* Oslo University Hospital, Oslo, Norway