HO usually occurs 3-12 weeks after spinal cord injury yet has been known to also develop years later.

Where does heterotopic ossification occur?

Heterotopic Ossification (HO) refers to the formation of lamellar bone inside soft tissue structures where bone should not exist. The development of HO is extra-articular and occurs outside the joint capsule.

What causes heterotopic ossification?

HO occurs after other injuries, too. HO has been known to occur in cases of traumatic brain injury, stroke, poliomyelitis, myelodysplasia, carbon monoxide poisoning, spinal cord tumors, syringomyelia, tetanus, multiple sclerosis, post total hip replacements, post joint arthroplasty, and after severe burns.