Anterior Oblique Dislocation. — In Bigelow's one reported case the head of the bone was high above the acetabulum and the limb crossed the opposite thigh, everted, and with the knee extended. Reduction as for everted dorsal disloca tion.
Dislocations Downward and Inward.— In both the obturator—or thyroid—and perineal varieties the head escapes through a rent in the lower and inner part of the capsule to lodge on the ob turator foramen, or to proceed farther and rest on the perineum. In either case the limb is flexed, abducted, and rotated outward. It cannot be extended and can only be adducted after flexion. The limb is shortened, the trochanteric re gion flattened, and adduction tense. The head of the femur may sometimes be felt on the foramen, always if it is in the per ineum, in which latter case the abnor mality of the position of the limb is much greater. Several patients are reported to have walked immediately after receiving a thyroid dislocation.
The common cause is violence received on the back of the pelvis while the thigh is somewhat flexed and abducted; but it may be extreme abduction alone. In perineal dislocations the laceration of the soft parts must be extensive.
Reduction is made by flexion of the hip to a right angle, traction with adduc tion, and then inward (or outward) rota tion while lowering the knee. Manipu lation may succeed with no rotation at all.
Dislocations Upward and Forward, and Inward and Forward (Suprapubic).— The limb is extended, markedly everted, and slightly abducted. The head of the femur is commonly to be felt in the groin (ilio-pectineal form) or may be above the pubes. The psoas-iliac and the great vessels are stretched across the head or may be ruptured. The head of the bone may have left the socket at its upper and inner part by hyperextension, or by ab duction and outward rotation, or the dis location may be secondary to an ob turator dislocation.
Reduction.—The head is to be drawn downward past the pubic ramus by di rect traction in the axis of the limb as it lies; then flexion is institnted while pressure is made against the head to pre vent its moving upward again; and fi nally inward rotation replaces the bone.
Dislocations Directly Upward (Supra cotyloid).—In the few recorded cases the head had been forced directly upward and lay just beneath the antero-inferior spine of the ilium. The limb was everted and abducted. Some of the patients have been able to walk with a limp.
These cases bear a close resemblance to everted dorsal dislocations. No defi nite rules for reduction have been laid down.
Dislocation Downward Upon the Tuber osity of the Ischium.—This dislocation is very rare because of the ease with which it may be conyerted into a dorsal or thyroid dislocation. The thigh is sharply flexed and abducted. Reduction is easy by traction in flexion.
Complications of Dislocations of the Hip.—Compound dislocations are very rare.
Injury to the femoral vessels may oc cur in forward and inward dislocations.
Fracture of the neck of the femur is usually caused by overzealous attempts at reduction. Ankylosis with the limb in a favorable position is the best that can be hoped for, except possibly in the young, when excision of the head of the bone may give some useful motion.
Treatment of Old Unreduced Disloca tions.—Of the operative procedures, re duction by arthrotomy gives a long list of deaths as opposed to two successes (by Parkes), while excision of the head, or of the head, neck, and trochanter, and sub trochanteric osteotomy have frequently decreased the disability. In many cases, however, the patients do reasonably well without operation, and these persons need expect no cure from the knife.