Fig. 109.—Early Tuberculous Disease of Right Hip-joint in a boy æt. 14, showing flexion, abduction, and apparent lengthening of the limb.
At first the attitude is maintained entirely by the action of muscles; but when it is prolonged, the muscles, fasciæ, and ligaments undergo shortening, so that it becomes fixed.
On looking at the patient, the abnormal attitude may not be at once evident, as he usually restores the parallelism of the limbs by lowering the pelvis on the affected side and adducting the sound limb. This obliquity or tilting of the pelvis causes apparent lengthening of the diseased limb, and is best demonstrated by drawing one straight line between the anterior iliac spines, and another to meet it from the xiphoid cartilage through the umbilicus; if the pelvis is in its normal position, the two lines intersect at right angles; if it is tilted, the angles at the point of intersection are unequal. The flexion may be largely compensated for by increasing the forward curve of the lumbar spine (lordosis), and by flexing the leg at the knee. There may also be an attempt to compensate for the eversion of the limb by rotating the pelvis forwards on the affected side.
Fig. 110.—Disease of Left Hip: position of ease assumed by patient, showing moderate flexion and lordosis.
Fig. 111.—Disease of Left Hip: disappearance of lordosis on further flexion of the hip.