Disruption of targeted muscle reinnervation due to heterotopic ossification in an amputated lower extremity.

A patient in his late 40s presented after 1-year following below knee amputation and targeted muscle reinnervation (TMR) with new prosthesis intolerance and pinpoint pain, suspicious for neuroma. X-ray confirmed fibular heterotopic ossification (HO). Operative revision identified HO encompassing a TMR construct with a large neuroma requiring excision and neuroplasty revision. Now approximately 1-year post procedure, the patient remains active, pain-free and ambulating with a prosthetic. Amputated extremities can be at risk for development of HO. Although described in literature, the pathophysiology and timeline for HO development is not well understood. Preventative measures for HO have been described, yet results remain variable. The gold standard for existing HO remains to be operative excision. Due to the unpredictable nature and debilitating presentation, risk of HO should be incorporated into patient-physician discussions. Additionally, new prosthetic intolerance absent of prior trauma should raise suspicion for possible HO development.