Combining results from hip impingement and range of motion tests can increase diagnostic accuracy in patients with FAI syndrome

Key points

1. 0181 patients were examined by two raters, with FAI diagnosis confirmed by symptoms, CAM or pincer morphology, and a positive intra-articular block.
2. 02Impingement tests AIMT, FADIR, and FABER showed good inter-rater agreement (kappa above 0.6).
3. 03AIMT and FADIR were sensitive (about 80%) but not specific (about 25%), so they help rule FAI out, not confirm it.
4. 04Limited passive internal rotation in neutral was specific (94%) but not sensitive (29%), so it helps confirm FAI when present.
5. 05Pairing a ruling-out test with a ruling-in test increases overall diagnostic accuracy.

How it was conducted

Design

Diagnostic accuracy and inter-rater reliability study (Level of evidence II)

Participants

81 patients assessed for FAI syndrome

Raters

Two independent raters performed the clinical tests

Reference standard

FAI diagnosis required symptoms, CAM or pincer morphology, and a positive intra-articular block

Tests assessed

Impingement tests (AIMT, FADIR, FABER) and passive range of motion tests

What they found

• AIMT, FADIR, and FABER showed inter-rater agreement kappa above 0.6.
• Passive range of motion tests, except extension, showed inter-rater agreement kappa above 0.4.
• AIMT and FADIR had sensitivity of 80% and specificity of about 25%, supporting use to rule out FAI.
• Passive internal rotation in neutral position had sensitivity of 29% and specificity of 94%, supporting use to rule in FAI.

Limitations

• Single-center sample of 81 patients limits the precision of accuracy estimates.
• Specificity of the impingement tests was low (about 25%), so a positive result alone is not informative.
• The most informative ruling-in test (limited internal rotation) missed most cases due to low sensitivity (29%).
• The reported abstract-level data give limited detail on confidence intervals around the accuracy estimates.

Why it matters

For patients

A single positive hip test does not confirm you have impingement, so your clinician will combine several tests and imaging before deciding.

For clinicians

Use AIMT or FADIR to help rule FAI out and limited internal rotation in neutral to help rule it in, rather than relying on one test.

For readers

This study shows why combining clinical tests, rather than trusting any single one, improves diagnostic accuracy for hip impingement.