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

In short

How accurate are physical examination tests for diagnosing hip impingement (FAI syndrome), and should they be combined?

No single hip test is accurate on its own. Impingement tests like AIMT and FADIR are good at ruling FAI out, while limited internal rotation is better at ruling it in, so combining tests gives the most useful picture.

Mixed pictureRead paper
Primary study81 ParticipantsModerate evidence

Key points

  1. 81 patients were examined by two raters, with FAI diagnosis confirmed by symptoms, CAM or pincer morphology, and a positive intra-articular block.
  2. Impingement tests AIMT, FADIR, and FABER showed good inter-rater agreement (kappa above 0.6).
  3. AIMT and FADIR were sensitive (about 80%) but not specific (about 25%), so they help rule FAI out, not confirm it.
  4. Limited passive internal rotation in neutral was specific (94%) but not sensitive (29%), so it helps confirm FAI when present.
  5. Pairing 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.

Source

doi:10.1007/s00167-020-06005-5

Read the original paper
Clinically assessing this area? See the hip & groin special tests.

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