Heterotopic Ossification at an Unusual Site: A Case Report

ABSTRACT

Heterotopic ossification (HO) is the formation of ectopic bone at non-physiological location, such as soft tissues around a joint.HO is a common complication seen after trauma and certain surgeries (e.g., total hip arthroplasty) involving specific regionssuch as hip. In neurogenic HO, ectopic bone develops in patients sustaining a spinal cord injury or traumatic brain injury(incidence 20–30%). Neurogenic HO characteristically involves major joints with hip joint being the most common, followed byelbow, shoulder, and knee joint. No reported case of HO in wrists, ankles, legs, and feet has been documented, making thesehighly rare locations. The ectopic bone may be asymptomatic or can cause significant functional impairment of the involvedjoint presenting as erythema, warmth, swelling with loss of range of motion; however, this case is a rare presentation involvingankle joint with no signs of inflammation. Plain X-rays and CT scans diagnose the new bone. Management involves primaryprophylaxis with NSAIDs, bisphosphonates (not commonly used), and radiation therapy. Surgical excision is the definitivetreatment. Neurogenic HO cases should undergo comprehensive and extended follow-up with attention to even rarely involvedsites such as ankle, wrists, hands, and feet.