Trauma & Sports

AIIS Avulsion Fracture: Groin Pain After a Kick

Acute groin pain after a missed kick: an AIIS avulsion is typical of young soccer players.

Updated: April 2026·Medically reviewed by Dr. Daniele Priano

Quick Answers

What is the difference between ASIS and AIIS avulsion?
The ASIS is the origin of sartorius; the AIIS is the origin of the direct head of rectus femoris, part of the quadriceps. Sprinting and kicking can cause avulsion of these immature apophyses. Many cases heal with non-operative care; displacement, symptoms and functional demands guide decisions.
How long to return to soccer?
There is no date that applies to everyone. Adequate healing assessed by your clinician, recovery of movement, strength and control, and tolerance of progressive sporting tasks are required. Normal walking does not mean readiness for sprinting, kicking or competition. Indicative timelines do not replace follow-up; pain during or after activity requires reduced loading and reassessment.
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AIIS avulsion fracture (Anterior Inferior Iliac Spine) is a typical avulsion injury in the adolescent soccer player. It occurs when the rectus femoris muscle of the quadriceps contracts with extreme power — particularly during a missed kick, a powerful shot or a sudden knee extension — and tears off a bone fragment from its insertion on the pelvis.

Here too the mechanism is age-related: in the adolescent, the tendon insertion on the bone is still maturing and gives way before the muscle. Pain is sudden, localized in the anterior groin region, and the athlete often describes a clear sensation of "tearing" during the gesture.

After first aid and an accurate clinical evaluation, a targeted X-ray confirms the diagnosis and shows any fragment displacement. The path is almost always conservative — rest, unloading, progressive recovery of mobility and a return-to-sport program built around the specific sports gesture, especially for young soccer players who will need to kick with power again.

⚠️ Early evaluation: it is reasonable not to delay assessment. Early orthopaedic evaluation allows accurate documentation of the avulsion, definition of the pathway and setup of the appropriate workload. In the vast majority of cases treatment is conservative; surgery remains rare and selective, reserved for cases with significant displacement.

Assessment and treatment

When to seek evaluation

  • Sudden acute groin pain during a kick or sprint
  • Sensation of 'tearing' in the anterior groin region
  • Inability to kick or extend the knee against resistance
  • Swelling and tenderness in the groin region
  • Limping and difficulty walking
  • Persistent groin pain, blocking or limited hip flexion during recovery requires reassessment, not stronger stretching.

What is evaluated

  • Detailed history of the traumatic movement
  • Knee extension against resistance test (painful)
  • AIIS palpation
  • Pelvic X-ray for diagnostic confirmation
  • Assessment of fragment displacement
  • Possible ultrasound or MRI for associated soft tissue injuries

Treatment options

  • Stop sport during the initial phase. Rest from sport, protected weight bearing and non-weight bearing are different instructions: your clinician specifies how much weight is allowed and for how long, according to the injury and healing.
  • Use crutches for as long as needed to respect prescribed weight bearing. Do not stop automatically after two or three weeks or solely because pain has improved.
  • Ice and analgesics in the acute phase
  • Stretch the rectus femoris only after adequate healing assessed at follow-up and specific clearance, without forcing knee flexion or hip extension.
  • Progressive quadriceps strengthening at the authorised stage. Even isometrics and straight-leg raising can create traction at the AIIS; antigravity work and advanced loading require specific instructions.
  • Return-to-sport work after confirmation of adequate healing and recovery of movement, strength and control; progression must be tolerated during, after and the following day. Absence of pain or elapsed weeks alone is insufficient.
  • Larger fragment displacement discussed case by case; surgery considered in selected cases

Frequently Asked Questions

What is the difference between ASIS and AIIS avulsion?▼
The ASIS is the origin of sartorius; the AIIS is the origin of the direct head of rectus femoris, part of the quadriceps. Sprinting and kicking can cause avulsion of these immature apophyses. Many cases heal with non-operative care; displacement, symptoms and functional demands guide decisions.
How long to return to soccer?▼
There is no date that applies to everyone. Adequate healing assessed by your clinician, recovery of movement, strength and control, and tolerance of progressive sporting tasks are required. Normal walking does not mean readiness for sprinting, kicking or competition. Indicative timelines do not replace follow-up; pain during or after activity requires reduced loading and reassessment.
How can apophyseal avulsions be prevented?▼
There is no measure that guarantees prevention. Reasonable practices include adequate warm-up, progressive muscle strengthening, sensible training-load management especially during growth spurts, and avoiding early intensive sports specialization. Stretching alone has not been shown to reliably prevent these injuries.
Is AIIS avulsion visible on X-ray?▼
Yes, in most cases the pelvic X-ray shows the detached bone fragment. In some cases, especially in early phases or in very young adolescents, ultrasound or MRI may be needed to confirm the diagnosis.
When can I start kicking again?▼
After healing is confirmed and the task is authorised, start with short, gentle passes from a stationary ball. Increase distance, volume and then power gradually, one demand at a time; game situations and competition follow tolerance of progressive training. Pain during, after or the following day requires stopping progression and reassessment.
Is eccentric strengthening really essential?▼
Eccentric work can be part of advanced strengthening when authorised, but no single exercise is mandatory for every patient. A step-down helps limb control but does not by itself demonstrate that the rectus femoris is ready for kicking or sprinting. Exercise choice, loading and progression depend on healing, strength, function and sport.
What should I do about persistent groin pain or blocked hip flexion?▼
Seek reassessment. After an AIIS avulsion, persistent anterior pain and limited flexion may also reflect mechanical impingement from a displaced fragment or prominent callus. This is not always the cause, but forcing the stretch is not the solution; your clinician decides which investigations are needed.

Important Notice: The information on this page is for educational and informational purposes only and does not constitute medical advice. Each clinical case is unique: the appropriate treatment is determined during the specialist consultation, based on a thorough clinical examination and, where necessary, diagnostic imaging. For any doubts or concerns, please consult a specialist.