Brachialis Muscle Ischemia Causing Elbow Flexion Deformity with Myositis Ossificans – A Case Report

Myositis ossificans (MO) is a rare entity of extra-skeletal bone formation in various muscles, most commonly in quadriceps, gluteals, small muscles of hand and brachialis, which often triggered by trauma or ischemia. It is first described in medical literature during the 17th–18th centuries, with early cases linked to traumatic injuries. Traumatic MO Formally classified by German pathologist Von Dusch in 1868. Historically, it was termed "rider's bone" due to its association with horseback riding injuries. Repeated trauma to the elbow from sports may be linked to the development of myositis ossificans traumatica (MOT). We report a case of MOT in a 26-year-old male who sustained non-traumatic ischemic compression during sleep and presented with severe pain and a fixed flexion deformity of the elbow. The patient typically presented as a painful, tender, enlarging mass, which was located in anterior distal humerus within brachial muscles of the upper arm, following subtle repetitive local trauma. Although it seems unnoticed, causing ischemia alteration in brachial muscles while he was sleeping on his volar aspect of the elbow for several months. Imaging studies, including ultrasound, X-ray, CT and MRI, revealed a bony mass in the anterior aspect of the right elbow and a history of brachial ischemia caused by sustained pressure. Biopsy histology and molecular biology studies confirmed the diagnosis of MOT. Clinically, MO may present as a painful soft-tissue mass, which could be confused with tumor or inflammatory lesions. MO goes through different phases of evolution, and its appearance on imaging varies depending on the stage of investigation. For differentiation diagnosis from soft-tissue tumors or other malignancies, comprehensive image studies and histology, molecular biology studies are compulsory.