To demonstrate the lordosis, the patient should be laid on a flat table; in the resting position the lordosis is moderate, when the hip is flexed it disappears, when it is extended the lordosis is exaggerated, and the hand or closed fist may be inserted between the spine and the table ([Fig. 112]).
Fig. 112.—Disease of Left Hip: exaggeration of lordosis produced by extending the limb.
When the functions of the joint are tested, it will be found that there is rigidity, and that both active and passive movements take place at the lumbo-sacral junction instead of at the hip. While rigidity is usually absolute as regards rotation, it may sometimes be possible with care and gentleness to obtain some increase of flexion. For diagnostic purposes most stress should therefore be laid on the presence or absence of rotation.
If the sound limb is flexed at the hip and knee until the lumbar spine is in contact with the table, the real flexion of the diseased hip becomes manifest, and may be roughly measured by observing the angle between the thigh and the table ([Fig. 113]). This is known as “Thomas' flexion test,” and is founded upon the inability to extend the diseased hip without producing lordosis.
Fig. 113.—Thomas' Flexion Test, showing angle of flexion at diseased (left) hip.
Swelling is seen on the anterior aspect of the joint; it may fill up the fold of the groin and push forward the femoral vessels. It is doughy and elastic, but may at any time liquefy and form a cold abscess. Swelling about the trochanter and neck of the bone may be estimated by measuring the antero-posterior diameter with callipers, and comparing with the sound side. Swelling on the pelvic aspect of the acetabulum can sometimes be discovered on rectal examination.