The Thomas test (or Hugh Owen Thomas well leg raising test) is a physical examination test, named after Dr. Hugh Owen Thomas (1834–1891), a British orthopaedic surgeon, used to rule out hip flexion contracture and psoas syndrome. Often associated with runners, dancers, and gymnasts who complain of hip "stiffness" and reported "snapping" feeling when flexing at the waist.
The patient supine on the examination table and holds the uninvolved knee to his or her chest, while allowing the involved extremity to lie flat. Holding the knee to the chest flattens out the lumbar lordosis and stabilizes the pelvis.
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:
- opposite/ contralateral hip flexes without knee extension- tight iliopsoas
- hip abducts during the test- tight tensor fasciae latae
- knee extension occurs- tight rectus femoris
- Lateral rotation of tibia- tight biceps femoris
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.
The test consists of 3 steps:
- Step 1: The patient lies supine on the examination table. The clinician passes the palm of his hand beneath the patients spine to identify lumbar lordosis.
- Step 2: The "unaffected" hip is flexed till the thigh just touches the abdomen to obliterate the lumbar lordosis. The pelvis should be in neutral (not tilted anteriorly or posteriorly).
- Step 3: The clinician then passively ranges the affected hip into extension. Once the pelvis begins to tilt anteriorly, stop the passive range of motion, hold the affected thigh in this position, and measure the angle between the affected thigh and table to reveal the fixed flexion deformity of the hip.
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