Etiology — what causes it

Symptomatic motion-related contact between the proximal femur and acetabulum, driven by morphology (cam, pincer, or mixed), repetitive end-range hip motion, and reduced soft-tissue capacity. The Warwick Agreement (Griffin et al., BJSM 2016) defined the diagnosis as the triad of symptoms, clinical signs, and imaging findings.

Epidemiology — who gets it

Morphological cam impingement is present on imaging in 15–30% of active young adults, but only a minority become symptomatic. Common in hockey, soccer, and martial arts athletes.

Clinical signs

Positive FADIR (flexion–adduction–internal rotation) reproduces deep hip pain (high sensitivity, lower specificity). Restricted hip internal rotation in flexion. Imaging confirms morphology (alpha angle on lateral view for cam; lateral center edge angle for pincer).

Symptoms

Deep groin or anterior hip pain, often described as a C-sign around the hip. Pain with deep squatting, prolonged sitting, and cutting. May include clicking or catching.

Best evidence for chiropractic treatment

The Warwick Agreement, FASHIoN trial (Griffin et al., Lancet 2018), and Mansell et al. (AJSM 2018) compared surgery and physiotherapy. Surgery has modest advantages for hip-related quality of life at 2 years, but physiotherapy alone produces meaningful improvements for many patients. Conservative care emphasizes activity modification, hip strength (especially deep external rotators and gluteals), motor control, and graded loading.

Subtypes

  • Cam morphology. Asphericity of the femoral head-neck junction.
  • Pincer morphology. Acetabular over-coverage.
  • Mixed (cam + pincer). Most common imaging finding.
  • Non-impingement type hip pain. Symptoms without morphology — managed similarly to other hip-region pain.

When to seek emergency care

Some symptoms need urgent medical attention — not a chiropractic visit. Call 911 or go to the nearest emergency department for: progressive limb weakness, loss of bowel or bladder control, saddle anesthesia (numbness in the groin/inner thighs), severe unrelenting pain unrelieved by position, signs of fracture after significant trauma, chest pain, stroke-like symptoms (face drooping, arm weakness, speech changes), or any rapidly worsening or unusual symptom.

Bottom line

Many FAI cases improve substantially with structured conservative care — surgery is not the default first answer.