What are the physical exam signs of femoral acetabulum impingement (Femoroacetabular Impingement)?

Physical Examination Signs of Femoroacetabular Impingement

The flexion-adduction-internal rotation (FADIR) test, also known as the impingement test, is the primary physical examination maneuver for detecting FAI syndrome, though a negative test is more useful for ruling out hip-related pain than a positive test is for confirming the diagnosis. 1, 2, 3

Primary Clinical Examination Findings

Pain Characteristics

• Groin pain is the hallmark symptom, though pain may also radiate to the back, buttock, or thigh 1
• Slow-onset, persistent groin pain is the most frequent initial presenting symptom 3
• Patients report clicking, catching, buckling, stiffness, giving way, and limited range of motion 2

Key Physical Examination Tests

FADIR (Flexion-Adduction-Internal Rotation) Test:

• The patient lies supine while the examiner flexes the hip to 90 degrees, then adducts and internally rotates the hip 2, 3
• A positive test reproduces the patient's typical groin pain 2
• Important caveat: This test has good sensitivity but poor specificity, meaning it is better at ruling out FAI when negative than confirming it when positive 1

FABER (Flexion-Abduction-External Rotation) Test:

• Also known as the Patrick test 1
• The hip is flexed, abducted, and externally rotated 1
• This test has lower diagnostic precision compared to FADIR 1

Range of Motion Findings

• Limited hip internal rotation is commonly observed, particularly in cam-type impingement 2
• Restricted hip flexion may be present 2
• Pain at end-range hip flexion combined with rotation is characteristic 1

Clinical Examination Limitations

Critical understanding: Physical examination alone has limited diagnostic utility for FAI syndrome 1. The consensus from the British Journal of Sports Medicine emphasizes that:

• Clinical examination tests cannot definitively distinguish FAI syndrome from other causes of hip-related pain 1
• Most clinical tests demonstrate good sensitivity but poor specificity 1
• A comprehensive approach combining symptoms, clinical signs, AND imaging findings is essential for proper diagnosis 1, 2

Differential Diagnosis Considerations

When examining for FAI, you must exclude more serious pathology first:

• In adolescents: Rule out slipped capital femoral epiphysis (SCFE), Perthes disease, infection, tumors, and fractures 1, 4
• The absence of groin pain helps exclude FAI syndrome and labral tears 1
• Consider referred pain from the spine or knee as alternative sources 1

Diagnostic Confirmation

Physical examination findings must be correlated with imaging:

• Plain radiographs showing cam morphology (alpha angle >60°) or pincer morphology (lateral center edge angle >40°) 1, 3
• MRI or MR arthrography to assess labral tears and cartilage damage 2, 5
• The diagnosis requires the triad of symptoms, clinical signs, AND imaging findings 1, 2