

The Thomas Test is mentioned several times in the literature to measure both shortening of the iliopsoas and to test for femoroacetabular impingement syndrome (FAI). McCarthy et al. (1995) obtained very good positive and negative likelihood ratios of 11.1 and 0.12, respectively, regarding the Thomas test’s ability to diagnose variable hip pathologies such as FAI. In addition, asymptomatic findings of FAI are very prevalent which makes the test only moderately useful. Furthermore, shortening of the iliopsoas cannot be reliably detected both visually and measured with a goniometer.
To perform the test, the patient lies on his or her back. The patient is asked to pull the non-testing leg toward the chest until the bulge in the lumbar spine smoothes out.
The test is positive when the extended leg lifts off the treatment table and the patient feels a stretch in the groin. If adduction of the extended leg is observed, the so-called J-sign, this could indicate a shortening of the iliotibial tract.