Influence of Naproxen on Heterotropic Bone Formation Following Hip Arthroscopy
Influence of Naproxen on Heterotropic Bone Formation Following Hip Arthroscopy
In a brief summary the study would like to evaluate the effectiveness of Naproxen in
 preventing radiographically detected heterotopic ossification following hip arthroscopy for
 the treatment of femoroacetabular impingement.
Heterotopic bone formation (HO) is a potentially serious complication of hip surgery. HO,
 defined as the formation of normal bone in an abnormal soft tissue location, results from
 alteration in the normal regulation of skeletogenesis. Although most patients remain
 asymptomatic despite HO development, two articles that included 10,826 patients from 37
 studies suggest HO may be associated with substantial compromise of function and range of
 motion even at low grades.In a large pooled incidence study, HO was estimated to be 43% in
 59,121 patients undergoing total hip arthroplasty, and 51% in 998 patients after acetabular
 trauma.

 Few studies have reported on the incidence of HO following hip arthroscopy. However, HO is an
 increasingly reported complication of arthroscopic treatment for femoroacetabular
 impingement(FAI). In a comparison of complications following arthroscopic treatment of FAI in
 8 case-series, ectopic ossification occurred in up to 6% of cases and accounted for 10 of the
 19 reported complications. Additionally, one recent study reported an HO incidence of 33% (5
 out of 15 patients) following hip arthroscopy in patients not prophylaxed with NSAID therapy.
 In our experience, HO occurs at a comparable or higher rate of 10% in those undergoing this
 procedure. The formation of ectopic ossification is triggered as a result of muscle damage
 during introduction of hip portals and is potentially augmented by seeding of bone shavings
 in the soft tissues created during burring of the femoral neck.

 Prophylaxis of HO targets the biochemical mechanisms of heterotopic bone formation by: 1)
 Disrupting inductive signaling pathways, 2) Altering osteoprogenitor cells in target tissues,
 and 3) Modifying the environment conductive to formation of heteroptic bone. The two
 mainstays of therapy are low dose radiation treatment and non-steroidal anti-inflammatory
 medications (NSAIDs). The efficacies of these treatments were found to be equivalent by Burd
 et al in 166 randomized patients. However, NSAID therapy was shown to be considerably more
 cost effective with lower rates of morbidity. Large randomized studies have subsequently
 shown large reductions in the incidence of HO using NSAID therapy in the perioperative
 period. The Cochrane review of 16 randomized trials in 5000 patients found one-half to
 two-thirds reduction in HO with indomethacin.Even less potent NSAID therapy has been
 effective in reducing rates of HO. Fransen et al reported a 30% reduction in HO during the
 HIPAID trial comparing perioperative ibuprofen with placebo in nearly 1000 patients. The two
 groups had no statistical difference in functional outcome despite the higher incidence of HO
 in the prophylaxed group.

 While NSAID therapy has been effective in reducing the incidence of HO, it is associated with
 potentially serious side affects. Fransen et al found 202 GI side effects in a metaanalysis
 of 4328 patients taking NSAIDs for HO prophylaxis.1 Of these, 138 were minor (e.g. nausea,
 dyspepsia, diarrhea) and 64 were major (e.g. hematemesis or melena). Overall, there was a 31%
 increase in the risk of GI side effects among patients taking NSAIDs. Furthermore, NSAID
 therapy could impair bone and/or soft tissue healing following this. These side affects could
 negate the benefit of NSAID therapy, especially if HO is asymptomatic in the majority of
 patients.

 We hypothesize that NSAID prophylaxis of HO may have a role in hip arthroscopy for the
 treatment of femoroacetabular impingement. All NSAIDs tested, with the exception of aspirin,
 have resulted in significant decreases in the incidence of HO following hip surgery including
 less potent regimens such as ibuprofen 1200 mg/day. Naproxen offers the advantage of twice
 daily dosing with similar potency to ibuprofen. It is readily available and inexpensive.
 Furthermore, in an unpublished series of 50 patients prescribed naproxen following hip
 arthroscopy for FAI, we have had no cases of HO at 6 month follow up compared to a 5-10% rate
 in patients who received no prophylaxis. We propose testing our hypothesis that perioperative
 naproxen will reduce the incidence of HO following hip arthroscopy in a placebo controlled,
 double-blinded, randomized controlled trial.
Inclusion Criteria:

 -  The patient is 18-80 years of age.

 -  The patient has provided written informed consent.

 -  The patient is scheduled for hip arthroscopy surgery for treatment of FAI

 -  The patient has an ASA of I, II, or III.

 -  The patients understands the explanation of the protocol.

 Exclusion Criteria:

 -  The patient has history of a major GI bleeding event

 -  The patients has a history of renal impairment or creatinine > 1.5

 -  The patient has taken NSAIDs within 48 hours of surgery or in the perioperative period

 -  The patient has a history of heterotopic ossification following surgery

 -  The patient has a hypersensitivity reaction to Naproxen

 -  The patient is undergoing a concomitant procedure in addition to treatment of FAI