The Thomas Test assesses tightness of which muscle groups?

• A. Rectus Femoris and Iliopsoas
• B. Rectus Femoris only
• C. Iliopsoas only
• D. Hamstrings

Answer: (A)

The Thomas Test is used to evaluate hip flexor length, specifically the two muscles that cross the hip and pull it into flexion: the iliopsoas and the rectus femoris. When you position the patient supine and bring one knee to the chest, you’re testing how far the hip can extend and whether the hip flexors are limiting that motion. If the thigh of the tested leg cannot lie flat on the table or if the hip remains flexed, this points to tight hip flexors, with iliopsoas often being the primary contributor. The rectus femoris can also be involved, especially in a variation of the test where knee position is considered, because it crosses both the hip and knee. In contrast, hamstring tightness is evaluated with other tests like the straight leg raise. So the test best identifies tightness in both the rectus femoris and the iliopsoas.