A 33-year-old man presents with chronic right hip pain from an injury 10 months ago. He was playing soccer when he went to kick a ball but was suddenly held up. When he held up to stop the forward movement of his leg, he felt a pop, and he points to the hip where the pop occurred. Since that time he has not been able to kick a soccer ball, but activities of daily living do not bother him. On examination, he has pain with resisted forward flexion of the right hip. Anteroposterior pelvis and oblique view radiographs of the right hip are shown in Figures 1 and 2.
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The pelvis provides attachment sites for many of the muscles that flex, extend, and rotate the hip. Musculotendinous attachments can pull bone off these sites, or cause avulsion fractures, with high-energy injuries. The most common sites of avulsion fractures in the pelvis include the ischial tuberosity, the anterior inferior iliac spine (AIIS), and the anterior superior iliac spine (ASIS). The AIIS is the attachment site for the rectus femoris, which flexes the hip. The ASIS is the attachment site for the sartorius and tensor fasciae latae, which flex and medially rotate the hip, respectively. The hamstrings (biceps femoris, semitendinosus, and semimembranosus) attach to the ischial tuberosity and extend the hip.1,2
The AIIS is the most common site for all avulsion fractures of the pelvis. The AIIS apophysis fuses at age 16 years on average, and epiphyseal avulsion fractures typically occur between the ages of 14 and 17. As with this case of a 33-year-old patient, the AIIS can also avulse when the apophysis is fused. Avulsion injuries typically occur with sporting activities such as running, jumping, or kicking sports. Patients often recall a sudden “pop” or snapping sound followed by pain and weakness. The initial treatment is nonoperative with a brief period of nonweight bearing and crutches. Physical therapy and weight bearing are initiated 1 to 2 weeks after the injury or when symptoms allow. Patients can often return to sport 2 months after avulsion fractures.1
Dagan Cloutier, MPAS, PA-C, practices in a multispecialty orthopedic group in the southern New Hampshire region and is editor-in-chief of the Journal of Orthopedics for Physician Assistants (JOPA).
Schiller J, Defroda S, Blood T. Lower extremity avulsion fractures in the pediatric and adolescent athlete. J Am Acad Orthop Surg. 2017;25:251-259.