Ischial apophyseolysis.

Abstract

Ischial Apophyseolysis is a traumatic avulsion of the ununited ossification center of the ischial tuberosity caused by a violent contraction of the hamstring muscles during strenuous activity, such as running or jumping. The condition is also known as “ischial epiphyseolysis,” “avulsion fracture of the ischial tuberosity,” “isolated fracture of the ischium,” “hamstring avulsion,” and “epiphysitis of the tuberosity of the ischium.” It occurs between the ages of puberty and twenty-five years. This corresponds to the time of appearance of the ossification center and its fusion to the ischial tuberosity. Ischial apophyseolysis is considerably more common in males than in females because the former engage in more physical activity during this period. In the typical case, the patient experiences sudden and severe pain in the buttock or hip region during some form of strenuous activity. Swelling may be present, and local tenderness can almost always be elicited by palpation. Additional activity or sitting aggravates the pain, while bed rest alleviates it. In most cases, the pain resolves in several days with conservative management. Excision of the avulsed apophysis is rarely necessary to control the discomfort. Usually, roentgenograms are not obtained during the acute phase. If taken early, they may show a thin crescentic bone density lying inferior to the ischial tuberosity corresponding to the avulsed apophysis. Unless the ischial apophysis is well developed, the x-ray findings may be negative. Roentgenograms obtained several weeks or months after injury demonstrate a large irregular crescentic mass of bone lying inferior to the ischial tuberosity (Fig. 1). Frequently, the findings on these films are misinterpreted as myositis ossificans or calcified hematoma. This mass was excised in the case reported by Winkler and Rapp (3). Histologically, the specimen revealed normal osseous tissue with normal marrow elements. Apparently, the avulsed apophysis continues to produce bone, which accounts for the large mass observed several months after injury. Calcification within a hematoma formation may contribute in part to the visualized mass, but is not the primary cause of the large calcification that is seen. Case Reports Case I: A 17-year-old basic airman was evaluated by the Orthopaedic Surgery Service of Wilford Hall USAF Hospital Dec. 7, 1956. He complained of pain in the left hip region that had persisted since his entry into the Air Force on Nov. 26. Physical examination revealed pain on straight leg raising, tenderness over the left ischial tuberosity, and slight atrophy of the left thigh in comparison with the right. Upon further questioning, it was learned that two years earlier the patient had experienced a “snap” with pain in the left hip region during a 75-yard dash. He remained in bed for two weeks after the injury and gradually resumed activity.