Acquired heterotopic ossification in the settings of cerebral anoxia and alternative therapy: two cases.

Acquired Heterotopic Ossification (HO) has been well described in the literature as a recognized complication following spinal cord injury, traumatic brain injury and joint arthroplasty. Commonly, large proximal limb joints are affected. The underlying mechanisms for ectopic bone formation remain poorly elucidated. Post-stroke hemiplegia as a cause of neurogenic HO is rare, and no published reports of HO occurring after anoxic brain injury in adults have been documented. This study reports two unusual cases of acquired HO: (1) Polyarticular HO involving the ankle joint in a 24-year-old Chinese female who suffered severe anoxic encephalopathy following near drowning which resulted in persistent vegetative state; and (2) Elbow HO in chronic post-stroke hemiplegia occurring as a complication of alternative therapy following repeated forceful manipulation by a traditional practitioner in a 46 year-old male.