Heterotopic Ossification

Heterotopic ossification (HO) is defined as the formation of extra-skeletal bone in muscle and soft tissues. HO may develop around joints after central neurologic injury, including traumatic brain injury (TBI) and spinal cord injury (SCI). A three-phase bone scan is the most sensitive imaging modality for early detection and assessment of HO maturity. Prevention strategies include ROM, NSAIDs, and bisphosphonates. Nonsurgical treatment with bisphosphonates and radiation therapy is appropriate for early treatment of HO. Although bisphosphonates are effective prophylaxis if initiated shortly after the trauma, mineralization of the bone matrix resumes after drug discontinuation. During the acute inflammatory stage, the patient should rest the affected joint in a functional position; once acute inflammatory signs subside, passive ROM exercises and continued mobilization are indicated. Surgical indications for excision of HO include improvement of function and standing posture, sitting or ambulation, independent dressing, feeding and hygiene, and repeated pressure injuries from underlying bone mass. The optimal timing of surgery is currently not established with new evidence suggesting that it is not necessary to wait for maturation of HO prior to surgical excision. The consulting physiatrist, in coordination with the inpatient multidisciplinary therapy team, may provide useful information to orthopedics by clearly determining the functional impact of HO in the setting of a neurologic disorder. In addition to the importance of ongoing orthopedic engagement, the consulting physiatrist should optimize the patient by managing risk factors that might influence HO recurrence such as treating spasticity, early identification and treatment of urinary tract infections, preventing pressure injury, and maximizing function prior to excision.