Manual of Surgery Volume Second: Extremities—Head—Neck. Sixth Edition.

by Alexis Thomson; Alexander Miles

In children who have walked, the head of the femur is pushed farther upwards on the dorsum ilii; the capsule becomes lengthened by supporting the weight of the body. That part of the capsule which arises from the lower margin of the acetabulum stretches across the socket and partly shuts it off from the rest of the joint cavity. In course of time the capsule becomes greatly thickened, and may present an hour-glass constriction about its middle, which may prove a serious obstacle to reduction. The socket becomes small and triangular, and there is almost no ledge against which the head of the femur can rest. A superficial depression may form on the ilium where it is pressed upon by the head of the femur, covered by the capsule; and in the course of years, as the head changes its position, several secondary sockets may be formed. No proper new bony socket forms like that in traumatic dislocations that remain unreduced because in the congenital variety the thickened capsule intervenes between the head of the bone and the dorsum ilii. The displacement of the head is most frequently backwards (dorsal luxation), and as the point of support thus falls behind the acetabulum the pelvis tilts forwards, and the lumbar spine becomes unduly concave (lordosis). The muscles of the hip and thigh alter in consequence of the changed relations; the gemelli, obturators, and piriformis are lengthened, the adductors, hamstrings, and ilio-psoas are shortened, while the glutei and quadriceps are but little altered. In rare cases the head is displaced upwards and lies immediately above the acetabulum.

Fig. 130.—Congenital Dislocation of Left Hip in a girl æt. 8. The patient is putting the whole weight on the dislocated limb.

Clinical Features.—The condition rarely attracts attention until the child begins to walk, but sometimes the unusual breadth of the pelvis, the presence of a lump in the buttock, snapping about the hip, or a peculiar way of holding the limb, leads the parents to seek advice early. In unilateral cases, when the child has learned to walk at the late age of two, three, or it may even be four years, it is noticed that the back is hollow and the buttocks unduly prominent, and that there is a peculiar and characteristic limp; each time the weight of the body is put upon the affected limb, the trunk makes a sudden dip towards that side. There is no pain on walking. The affected limb is shortened, as is shown by the projection of the great trochanter above Nélaton's line; the shortening gradually increases, and in time may amount to several inches. It is partly compensated for by resting the affected limb on the balls of the toes and flexing the knee on the sound side. The gluteal fold is shorter, deeper, and higher than on the healthy side, and on account of the obliquity of the pelvis the spine shows a lateral curvature, with its concavity to the affected side. The movements at the hip-joint are free in all directions except abduction; on practising external rotation it is often found to be abnormally free; lastly, in young children, if the pelvis is fixed, the head of the bone may be made to glide up and down on the ilium.

In bilateral cases the trunk appears well grown in contrast to the short lower limbs, the hollow of the back is exaggerated, the abdomen protrudes, the perineum is broadened, and the buttocks are unduly prominent. The gait is waddling like that of a duck, the trunk lurching from one side to the other with each step. In untreated cases the deformity and disability become more pronounced as the capsular and round ligaments are further stretched, the shortening and limp become more marked, the patient is easily fatigued by walking or standing, and is usually unfitted for earning a living. We have had under observation, however, an adult male with bilateral dislocation and extroversion of the bladder, who efficiently performed the duties of a carrier for many years.

Except in fat infants, the diagnosis is not difficult; the absence of pain and tenderness, the freedom of motion and the absence of the head of the femur from its normal position, differentiate the condition from tuberculous disease of the joint, and from coxa vara and other deformities in the region of the hip. Trendelenburg's test consists in noting the relative level of the buttocks when the patient stands on the affected leg. Normally the buttocks remain on the same level when the patient stands on one leg; in congenital dislocation the buttock of the limb raised from the ground drops to a lower level; in coxa vara it rises higher.

In paralytic conditions at the hip there may be considerable resemblance to dislocation, but the muscles are slack and wasted, and the normal attitude can easily be restored by pulling on the limb. The most certain means of diagnosis is by the X-rays, which show the position of the head of the bone in relation to the acetabulum, and any torsion of the neck of the femur that may be present. This last point is determined by taking a series of skiagrams in different positions of the limb; these are also useful in correcting erroneous impressions as to the angle of the neck of the femur.

Treatment.—We are indebted to Paci, Schede, Calot, Lorenz, and Hoffa for the rational treatment which seeks to reduce the dislocation by manipulation.

Reduction by Manipulation (Method of Lorenz).—The child is anæsthetised and placed on its back with the legs over the end of the table. While an assistant steadies the pelvis, the surgeon pulls on the limb so as to bring the trochanter down to Nélaton's line; this is followed by forced rotation outwards and inwards and forcible abduction to a right angle, and by kneading the adductors till they are stretched and torn. The next step is to stretch the hamstrings, and this is done by raising the foot, without bending the knee, until the front of the thigh meets the abdomen, and the toes the face. To stretch the anterior muscles, the patient is turned on the side or face, and the hip is hyper-extended both in the straight and in the abducted position. The stage is now reached at which attempts at reduction may be made; the child is again laid on its back, the surgeon grasps the knee, flexes the thigh to a right angle, rotates laterally, and slowly flexes and abducts, while the thumb pushes from behind on the trochanter, trying to guide and lift it over the rim of the socket as the hip reaches the over-abducted position. Lorenz uses a wedge of wood padded with leather about 3 inches high to rest the trochanter upon while attempting to lift it forward. When reduction takes place, there is generally a sound and a sudden jump, as in reducing a traumatic dislocation.