Prognosis.—Reduction is usually fol lowed by repair of the damage done, and within a few weeks the joint is as useful as ever. Occasionally, however, a perma nent laxity of the capsule remains, which allows the dislocation to recur on more or less slight provocation, and with each recurrence the tendency grows more marked. Occasionally, also, without any unusual evidence of injury to the nerves at the time of occurrence of the accident, a dislocation may be the starting-point of an intractable neuralgia, or it may pre dispose the joint to rheumatism. The complications above mentioned render the prognosis more grave.
In old unrednced dislocations the prognosis is different for every individual case. In some the new joint will become fairly useful, in others not so; yet the prospect of relief by operation is none of the brightest.
Treatment. — A recent dislocation should be inamediately reduced urdess great inflammatory reaction, swelling, or shock render the infliction of pain or the use of anmsthetics inadvisable.
Ancesthetics are of use to overcome the resistance of the muscles which, con tracted by pain or fear of pain, oppose the manipulations necessary for reduc tion, or in case the patient cannot or will not suffer the pain incident to those ma nipulations. Reduction may usually be effected in "primary" anwsthesia. Ether is safer than chloroform for this purpose.
The choice of the method of reduction depends upon the recognition of the ob stacles to reduction. Aside from mus cular opposition, the usual obstacle is the resistance offered by untorn ligaments or portions of the capsule to motion in certain directions. Other obstacles are interposition of the ligaments or mus cles, and these may be of such a nature as to demand operative interference.
The older methods of reduction by means of direct pressure on the head of the bone or traction by hand, by pulleys, or by electric force have been, in great measure, superseded by the more scien tific and practical method of reduction by manipulation, in which, by a succes sion of gentle movements, the head of the bone is brought opposite the tear in the capsule, the opening is enlarged by relaxation of its sides, and the head of the bone slipped into place by leverage on the untorn portions of the capsule and ligaments, aided, if need be, by trac tion and pressure on the bone.
In old dislocations the manipulations useful in recent cases are much less likely to succeed, owing to the firm adhesions binding the head of the bone in its new situation and the obliteration of the dis used articular cavity. Moreover, strong traction may be required to overcome the contraction of the muscles. Interference in such cases is unavoidably blind and uncertain, and involves much more ex tensive laceration than took place at the time of the original injury. So .many accidents have followed attempted re duction by manipulation in these cases that, if cautious manipulation fails to effect reduction, it is better to leave the dislocation unreduced in the majority of cases; or, if the loss of function is so g,reat as to induce the surgeon to run the risk, an open arthrotomy may be done with the hope of dividing the opposing structures, opening up the old socket, and replacing the dislocated bone.
The accidents which follow ill-advised attempts at reduction are usually fract ure of the bone or rupture of vessels, leading to hfemorrhage, gangrene, or aneurism. More rarely injury to large nerves has occurred, and even complete avulsion of a limb has been recorded.
After-treatment.—After reduction the joint need usually be kept immobilized only a few days, and excessive motions avoided for a few weeks. Some disloca tions require special dressings (e.g., clav icle). Gentle passive motion should usu ally be begun within at least three weeks to prevent adhesions.
Habitual dislocations have been cured at the inner end of the clavicle by peri articular injections of alcohol (Stimson) and at the shoulder by injections of tinct ure of iodine. But this method of pro ducing adhesions offers so grave risks of ankylosing the joint that in the more important joints it is advisable, if the tendency cannot be overcome by the pro longed wearing of an immobilizing ap paratus, or one which allows only slight motion, to excise, or take a "reef" in, the lax portion of the capsule.
Congenital Dislocations.—Under this head are included all dislocations sup posed to have existed at birth—although sometimes not diagnosed for months or years—and to have been caused by a mal development of the joint, hydrarthrosis, paralysis, etc. Dislocations produced traumatically in vier° or during delivery are excluded.