_Second Stage._--This probably corresponds with commencing disease of the articular surfaces, and progressive involvement of all the structures of the joint. The child complains more, and usually exhibits the attitude of abduction, eversion, and flexion (Fig. 109). [Illustration: 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. [Illustration: FIG. 110.--Disease of Left Hip: position of ease assumed by patient, showing moderate flexion and lordosis.] [Illustration: FIG. 111.--Disease of Left Hip: disappearance of lordosis on further flexion of the hip.] 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). [Illustration: 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.