heterotopic ossification in SCI
/ HET-er-oh-TOP-ik; OSS-ih-fih-KAY-shun /
Bone belongs inside the skeleton, not in the soft tissues around a joint. But after certain injuries the body sometimes 'misfiles' bone, laying down real, hard bone in the muscles and connective tissue where it has no business being. When this happens around the joints of someone with a spinal cord injury, it is called heterotopic ossification (the word simply means bone forming in the wrong place). It usually shows up in the first weeks to months after injury, most often around the hips, and it can quietly stiffen a joint before anyone realises what is happening.
The early signs are easy to mistake for something else: a joint below the level of injury becomes warm, swollen, and harder to move, sometimes with a low fever — a picture that can look like a blood clot or an infection, which is why it must be properly investigated. Inside, immature bone is being deposited in the soft tissue around the joint. Over weeks that bone matures and hardens; in the worst cases it can bridge across a joint and lock it (ankylosis), so a hip or knee that should bend freely becomes a rigid block. The trouble is that a stuck joint makes sitting, positioning, and transfers difficult, raises pressure-injury risk, and worsens spasticity and hygiene. Why it happens after SCI is not fully understood, which is part of why it can be hard to prevent.
In rehabilitation, heterotopic ossification matters because catching it early gives the best chance of keeping the joint moving. Gentle maintenance of range of motion, medications that can slow new bone formation, and — once the bone is mature and the joint is badly limited — sometimes surgery to remove it, all have a role, chosen carefully because aggressive treatment too early can backfire. The honest message is that it is partly preventable and manageable but not fully curable, and that protecting joint mobility from the start pays off.
Two months after a T6 injury, a man's right hip becomes warm, swollen, and stiffer to bend during therapy. Imaging confirms heterotopic ossification rather than a clot. The team continues careful range-of-motion work and starts treatment to slow the bone, keeping enough hip movement for him to sit comfortably in his wheelchair.
A warm, swelling, stiffening joint below the injury can be heterotopic ossification — caught early, motion can often be preserved.
A warm, swollen joint after SCI can mimic a deep-vein clot or infection, so it must not be assumed to be heterotopic ossification without proper assessment. And HO is not curable, only managed: the goal is to preserve useful joint motion, not to guarantee a normal joint.