Heterotopic Ossification: A Recurrence Model and Novel Approach to NSAID Prophylaxis




Juarez, Jessica K.


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Heterotopic ossification (HO) describes aberrant bone formation in soft tissue such as joints and muscle tissue, and is a complication of traumatic injury. The pathogenesis of HO is poorly understood, however, a common complication is chronic inflammation, which is also implicated in the osteogenic cascade. The current standard of care for trauma-patients with HO is excision and administering prophylactic radiation therapy and systemic non-steroidal anti-inflammatory drugs (NSAID). Treatments are based on several factors, including severity of trauma and ectopic bone formation potential. Systemic NSAID delivery reduces the inflammatory response but interferes with wound healing, and results in gastritis which can contribute to patient non-compliance. Following excision, HO recurrence is also a possibility. We hypothesized that local NSAID delivery would prevent primary ectopic bone formation when delivered at the time of injury in a rat tibialis anterior, and that local NSAID delivery would prevent recurrent HO following excision of established HO. The major findings of this study were that 1) locally delivered NSAIDs did not prevent primary HO when delivered at the time of injury, and 2) recurrence of HO was not observed in either the control or NSAID treatment groups following excision of established HO. We conclude that local NSAID delivery at the time of induction does not prevent primary HO formation. Additionally, recurrence is not observed in either control or treatment groups following partial excision of established bone treated with locally delivered NSAIDs. However, bone volume reduction is observed four weeks following NSAID delivery in both treatment and control groups. Further investigation into treatment timing, treatment dose, and delivery vehicle is warranted for both primary HO prevention and recurrence following excision.