ASIS Avulsion Fracture: Sudden Hip Pain in Athletes

ASIS avulsion fracture (Anterior Superior Iliac Spine) is a typical avulsion injury in adolescent athletes. It happens when a powerful contraction of the sartorius muscle — during a sprint, a kick, a jump or a change of direction — tears off a small bone fragment at the point where the tendon attaches to the pelvis.

In the growing skeleton the apophyseal nucleus (where the tendon attaches to the bone) is less resistant than the tendon itself: under very intense load, it is the bone that gives way before the muscle. This is why the same gesture, in an adult, would more likely cause a muscle strain rather than a bone avulsion.

Pain is acute, immediate, with inability to continue sports activity and obvious limping. Diagnosis is based on the history of the traumatic gesture, clinical examination and a targeted X-ray. In the vast majority of cases the path is conservative — rest, unloading, progressive return and careful return-to-sport — aiming to allow solid consolidation of the fragment and minimize the risk of recurrences or new avulsions at other apophyseal sites.

⚠️ Evaluate within 5–7 days: also for apophyseal avulsions, the first few days are when treatment options are best decided. Prompt orthopaedic evaluation allows accurate measurement of the fragment displacement, distinguishes the cases that benefit from conservative treatment alone from the rare ones that require surgical stabilization, and lets the right unloading program start immediately.