Review Question - QID 4485

Radiographs are extremely useful in the staging of heterotopic ossification, and will show the development of sharp cortical margins once the lesion has reached maturity.

Heterotopic bone is a condition in which lamellar bone forms in non-ossified soft tissues. In the early stages, studies such as MRI and bone scan are more sensitive for diagnosis, as radiographs may appear normal for the first three weeks. After the appropriate diagnosis is made, sequential radiographs are useful for monitoring the progression of the ossification. Once it has reached the mature stage, sharp cortical margins will appear, and surgical resection may be considered.

Cipriano et al. review heterotopic ossification following traumatic brain and spinal cord injuries. They discuss that the rate of radiographic recurrence is high (82-100%), but that that the rate of clinically significant recurrence is much lower (17-52%).

Figure A is a lateral radiograph of an elbow showing extensive heterotopic ossification with sharp cortical margins. This is consistent with heterotopic ossification in the mature stage.

Incorrect Answers:
Answer 1: Waiting for maturity has been found by some studies to decrease the chance of recurrence when compared to early excision.
Answer 3: Bone scans may still be positive after the lesion has reached maturity.
Answer 4: Duration from initial injury does not always correlate with level of maturity.
Answer 5: Alkaline phosphatase levels may aid in the diagnosis of heterotopic ossification, but are not used to assess the level of maturity of the lesion.