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A 13-year-old adolescent presents with right hip pain after a fall during a soccer match earlier in the day. He reports stopping abruptly and falling forward in pain. He is now having difficulty bearing weight on the right leg and cannot flex his hip. A radiograph is ordered (Figure).
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The patient has an avulsion fracture of the less trochanter. Avulsion fractures are commonly seen in the pediatric population at secondary ossification centers including the ischial tuberosity, anterior superior iliac spine, and anterior inferior iliac spine. They are less often found in the tibial tubercle, calcaneus, and greater and lesser trochanters.1,2
Secondary ossification centers act as attachment sites for tendons and ligaments and do not contribute to the length of bone. Secondary ossification centers generally fuse by age 17 so the most common age group for avulsion fractures are adolescent athletes. In adolescents, the tendon attachment is stronger than the growth plate so sudden contraction of the attached tendon/muscle can result in an avulsion injury.1,2
Avulsion injuries are diagnosed radiographically in most cases and advanced imaging is not necessary unless the diagnosis is in question. Isolated lesser trochanter avulsion fractures occur with a sudden contraction of the iliopsoas muscle (hip flexor). Patients present with groin pain, difficulty ambulating, and inability to flex the hip. Lesser trochanter avulsion fractures are treated nonoperatively with a 3 to 4 week period of rest and crutches for support, followed by a gradual rehabilitation back into athletic activities. Sports should be resumed when the patient is asymptomatic and there are radiographic signs of healing, which may take 2 to 3 months.1,2
The prognosis for lesser trochanter avulsion injuries is excellent and surgery is only considered if patients develop a symptomatic nonunion and/or a painful exostosis. Surgery involves removal of the painful nonunion with reattachment of the iliopsoas to the proximal femur.1,2
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.
References
1. Tahir T, Manzoor QW, Gul IA, Bhat SA, Kangoo KA. Isolated avulsion fractures of lesser trochanter in adolescents – a case series and brief literature review. J Orthop Case Rep. 2019;9(1):11-14.
2. Schiller J, DeFroda S, Blood T. Lower extremity avulsion fractures in the pediatric and adolescent athlete. J Am Acad Orthop Surg. 2017;25(4):251-259. doi:10.5435/JAAOS-D-15-00328
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