We present the case of a 4-year-old female with a complex fracture of
the left hemipelvis who, on follow-up CT imaging, developed new ossifi
c densities within the peripelvic soft tissues of the contralateral si
de. Three-dimensional surface reformations of the pelvis demonstrated
myositis ossificans along the course of the right sacrospinous ligamen
t, thus elucidating unsuspected ligamentous injury and implying prior
instability.