Heterotopic ossification is the formation of mature lamellar bone in extra-osseous soft tissues. It can be initiated by injury, viral infection, overuse or occur spontaneously. Extensive heterotopic ossification of a joint can lead to clinically important contractures and even complete ankyloses.

Symptom management may exist of corticosteroids, nonsteroidal anti-inflammatory drugs (NSAIDs).

The first features are often tumour like smellings.