Fig. 356
Inverted Y-ligament.
Symptoms and Signs.
—These vary decidedly in the different forms. In every case where the head of the bone rests on a higher level than the acetabulum there will be shortening. In nearly every instance a certain degree of flexion is present. In anterior displacements there is generally abduction and outward rotation. When the head of the bone is beneath the pubes or in the obturator foramen the limb may be lengthened as well as flexed, while the trochanter is shifted to a correspondingly lower position. In most instances the head of the bone can be felt in its abnormal position, and muscle spasm is always a pronounced feature, especially when there is actual elongation and muscles are really stretched. In the backward displacements adduction and inward rotation are the conspicuous features, the reverse of those of forward dislocation. When the head of the bone is actually in the ischiatic notch, and even when it is on the dorsum of the ilium, the limb is the more flexed, while the trochanter will be found above Nélaton’s line. [Figs. 357] and [358] illustrate the two types of anterior and posterior displacement, with the usual and predominating postural features, while [Figs. 359], [360], [361] and [362] (from Lejars) portray the anatomical features of the four principal types in graphic form. By these can be determined the class to which the dislocation belongs.
Fig. 357
Anterior dislocation of head of femur. (Lejars.)
Fig. 358
