The Thomas test is a physical examination test, named after the Welsh orthopaedic surgeon, Hugh Owen Thomas (1834–1891), to rule out hip flexion contracture (fixed partial flexion of the hip) and psoas syndrome (injury to the psoas muscle).

Description

The test consists of 3 steps: It is important to control the pelvic tilt to ensure that the Thomas test is valid for evaluating peak hip extension angle.

Interpretation

If the iliopsoas muscle is shortened, or a contracture is present, the lower extremity on the involved side will be unable to fully extend at the hip. This constitutes a positive Thomas test. Sometimes, with a very flexible patient, the Thomas test will be normal despite a psoas dysfunction being present. However, in the patient with a normal hip joint, a positive test is a good indicator of psoas hypertonicity. Other signs from the Thomas test: The hip flexion contracture is physiologic in the first 3 months of life and if it is absent in this period it may be a sign of developmental dysplasia of the hip. It is used to identify unilateral fixed flexion deformity of the hip.

Risk factors & associations

Psoas syndrome is often associated with runners, dancers, and gymnasts who complain of hip "stiffness" and reported "snapping" feeling when flexing at the waist.