Hi
It is my understanding that their is a difference between myositis ossificans and heterotopic bone formation, as seen in head injuries.
There appears to be an increased amount of abnormal bone growth at injury sites after a head injury - cause unknown but possibly related to altered bone growth factor control following brain damage. It is critical that joint mobilisation does not aggravate the joint, as this is likely to accelerate the abnormal bone deposition.
Ongoing scanning is required to ascertain whether the heterotopic bone is affecting the joint line. If not, muscle stretching and gentle joint mobilisation is required to avoid contractures.
If vthe bone is affecting the joint line, an orthopaedic or neuro specialist needs to judge the risks of removing the bone. This is a difficult decision, as further surgery can also accelerate the abnormal bone growth, and you may be worse off. In a paediatric patient, growth plates are also a priority.
Hope this helps.