Traumatic heterotopic bone formation in the quadriceps muscle. No progression by continuous passive motion in rabbits.

One hind limb in each of 20 New Zealand White rabbits was immobilized for 3 weeks together with daily forcible manipulation to induce heterotopic bone formation in the quadriceps muscle. The rabbits were then divided equally into a control group and a group treated with continuous passive motion (CPM). The effect of CPM on the development of heterotopic bone formation was assessed by radiographs of the femur and by histology. Treatment with CPM did not lead to increased heterotopic bone formation, as compared to the control group.