[Illustration: FIG. 72.--Dislocation of Right Femur on to Dorsum Ilii.] _Clinical Features._--The affected limb is flexed, adducted, and inverted, so that the knee crosses the lower third of the opposite thigh, and the ball of the great toe lies on the dorsum of the sound foot. There is shortening to the extent of from 1-1/2 to 2 inches, the trochanter being displaced above Nélaton's line, and lying nearer to the anterior superior iliac spine than on the normal side. The patient is unable to move the limb or to bear weight upon it; abduction and lateral rotation are specially painful; and traction fails to restore the limb to its proper length. On making these attempts a characteristic elastic resistance is felt. The head of the femur in its new position may sometimes be felt through the fibres of the gluteus maximus, but swelling of the soft parts often obscures this sign. The normal depression behind the great trochanter is lost, the gluteal fold is raised, and there is often a degree of lordosis which compensates for the flexion. The fingers can be pressed more deeply into Scarpa's triangle on the dislocated than on the normal side--a point in which this injury differs from fracture of the base of the neck of the femur. In a certain number of cases the lateral limb of the [inverted Y]-ligament is ruptured and the limb is everted--_dorsal dislocation with eversion_. [Illustration: FIG. 73.--Dislocation on to Dorsum Ilii. Note relation of neck of femur to tendons of obturator internus and gemelli (diagrammatic).] #Dislocation into the Vicinity of the Great Sciatic Notch#, or "_dislocation below the tendon_."--This variety of backward dislocation is less common than that on to the dorsum, although produced in the same way. The head of the femur passes beneath the obturator internus, and this tendon, catching on its neck, checks its upward movement (Fig. 74). The _clinical features_ are the same as those of the dorsal variety, but, on the whole, are less marked. _Differential Diagnosis._--Backward dislocation of the hip is usually easily recognised. When dislocation below the tendon occurs in a stout person, however, it is liable to be overlooked on account of the difficulty of feeling the displaced bone, and of the comparatively slight amount of deformity present. The nature of the accident, the absence of broadening of the trochanter, and the adduction and inversion of the limb are usually sufficient to prevent a dislocation being mistaken for an impacted extra-capsular fracture. #Dislocation into the Obturator Foramen# (Fig. 71).--This dislocation is produced by great force applied from behind while the thigh is flexed and abducted, as when a weight falls on the back of a man stooping forward with the legs wide apart. It may also result from violent abduction by wide separation of the thighs.