[Illustration: FIG. 114.--Tuberculous Disease of Left Hip: third stage, showing adduction and shortening.]
When adduction is pronounced, the patient is unable to restore the normal parallelism of the limbs, and the knee on the affected side may cross the sound limb. There is a deep groove at the junction of the perineum and thigh, great prominence of the trochanter, and the pelvis may be tilted to such an extent that the iliac crest comes into contact with the lower ribs.
As a result of the pressure of the carious articular surfaces against one another, the acetabulum is enlarged and the upper end of the femur is drawn gradually upwards and backwards within the socket. Examination will then reveal the existence of a variable amount of _actual shortening_; it will also be found that the trochanter is displaced above Nélaton's line, while above and behind the trochanter there is a prominent hard swelling corresponding to the enlarged acetabulum.
There may, therefore, be a combination of real and apparent shortening together amounting to several inches (Fig. 115).
[Illustration: FIG. 115.--Advanced Tuberculous Disease of Left Hip-joint in a girl æt. 14, showing flexion, adduction, shortening, and iliac abscess.]
In cases of long standing, beginning in childhood, the shortening is still further added to by deficient growth in length of the femur, and it may be of all the bones of the limb; even the foot is smaller on the affected side.
The most reasonable explanation of the attitudes assumed in hip disease is that given by König. If the patient walks without crutches, as he is usually able to do at an early stage of the disease, the attitude of abduction, eversion, and slight flexion enables him to save the limb to the utmost extent; on the other hand, if he uses a crutch, as he is obliged to do at a more advanced stage, he no longer uses the limb for support, and therefore draws it upwards and medially into the position of adduction, inversion, and greater flexion. Similarly, if he is confined to bed, he lies on the sound side, and the affected limb sinks by gravity so as to lie over the normal one in the position of adduction, inversion, and flexion. König's explanation accords with the fact that in the exceptional cases which begin with adduction and inversion we have usually to deal with a severe type of the disease, associated with grave osseous lesions--precisely those cases in which the patient is compelled from the outset to lie up or to adopt the use of crutches. Further, the transition from the abducted to the adducted position usually follows upon such an aggravation of the symptoms that the patient is no longer able to walk without the assistance of a crutch.