Evaluation of serum osteoblast mitogenic activity in spinal cord and head injury patients with acute heterotopic ossification

Study Design. This was a blind, prospective study of the effect of sera from patients with spinal cord and head injuries on osteoblast proliferation. Objectives. The authors studied whether a humoral factor that stimulates the formation of heterotopic bone is released into the circulation after a neural injury. Background Data. Other authors have shown that a humoral osteoinductive factor may be released after head and spinal cord injuries. Methods. Serum was obtained at certain times throughout the first 12 weeks post-injury and from control subjects. It was incubated with osteoblasts harvested from fetal rats, as well as with fibroblast controls. Results. There was a significant rise in serum mitogenic activity after injury in both groups. When patients that developed heterotopic ossification ware compared to other patients and controls, no significant differences were seen. Conclusions. This in vitro study fails to support a humoral mechanism for heterotopic ossification after spinal cord or brain injuries.