504 - Myositis Ossificans in the Right Shoulder Post-fall Due to Stroke Recrudescence

Case Diagnosis: Myositis Ossificans

Case Description: 74-yo F w/ PMHx of ischemic stroke w/ R-sided deficits presented w/ a traumatic ground-level fall in the shower due to R-sided weakness, along with mild R facial droop and dysarthria. She was diagnosed with transient focal neurological deficits due to stroke recrudescence and R pubic ramus fracture. During her inpatient rehabilitation stay, she reported new R arm weakness and pain during therapy. A hard mass was palpable on exam. R shoulder XR revealed a 11.8 cm heterogeneous soft tissue calcification at the lateral proximal R humerus, and US revealed it to likely be myositis ossificans. Patient denied a previous history of trauma to that shoulder. Patient's shoulder pain was managed appropriately until her discharge along with implementing gentle free-range of movement exercises.

Discussions: Myositis ossificans (MO) is a subtype of heterotopic ossification (HO), which is the formation of bone in atypical, extraskeletal tissues, muscles in this case, that typically occurs following a trauma. It likely occurs due to inappropriate differentiation of fibroblasts into osteogenic cells, however other pathophysiology hypotheses have been made. Classic presentation is pain and stiffness at the specific area after blunt trauma, with males aged 15-35 the most affected population. The other subtype, neurogenic HO, typically occurs after an acute stroke or traumatic brain injury and in females > 65 years old. PMR can play a significant role in treating MO through implementing proper and creative pain therapies and tailoring specific exercise programs to improve range of motion and function.

Conclusions: Although MO is a relatively rare condition that affects mostly young individuals who participate in athletics, it can develop in any individual of any age who suffers a trauma, such as a fall or car accident. PMR can play an important role in maximizing their recovery potential through targeted pain management and collaborative interdisciplinary approaches.