An apophysis is a secondary ossification center that serves as an insertion site for a tendon or large muscle. Sudden trauma or stress to one of these areas prior to complete ossification can result in an avulsion fracture through the apophysis, especially during a period of rapid bone growth.


Susceptible ages: adolescent, typically 11 to 15 years of age


Sites of possible apophyseal injuries that may be associated with hip pain:

(1) greater trochanter

(2) lesser trochanter

(3) ischeal tuberosity

(4) iliac crest

(5) anterior superior or inferior iliac spine


Clinical features:

(1) The athlete is involved in a sport which involves running.

(2) The athlete complains of the sudden onset of hip pain while sprinting, often hearing or feeling a "pop".

(3) The patient experiences immediate limping and disability.

(4) The pain is made worse on resistance testing and there is a decreased range of motion.

(5) The patient assumes a position that reduces tension on the affected muscle (varies with the affected apophysis).

(6) A palpable and tender swelling, lump or nodule may be present. The site may show overlying ecchymosis.

(6) Imaging studies show a fragment of displaced bone, with plain X-ray or CT scan superior to MRI. Usually the bone fragment is not displaced very far because of the surrounding periosteum.


Prognosis is affected by the size and displacement of the bone fragment. A fibrous non-union with prolonged disability may occur if the dislodged bone fragment is > 2 cm in size or is displaced more than 1-3 cm.


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