Three-view radiographic assessment of heterotopic ossification after acetabular fracture surgery.

A random sample of 100 patients who had operative treatment for a fracture of the acetabulum, an otherwise normal appearing hip joint, and at least one year of follow-up were analyzed to assess heterotopic ossification (HO) and its relationship to hip motion. The extent of HO was graded in a blinded fashion according to the Brooker classification, which relies solely on the anteroposterior (AP) view, as well as a modified classification using three radiographic views (AP pelvis, internal, and external Judet oblique views). For each patient, range of motion of the affected hip was compared with that of the contralateral normal limb. There were 16 cases with disagreement between the two methods. As opposed to the Brooker method, the modified classification provided an accurate correlation with the actual hip range of motion.