CHAPTER XXXV
.
DISLOCATIONS.
A sprain has already been described as a momentary change of emplacement or disturbance of the normal relations between joint surfaces, which, so far as displacement is concerned, is but a momentary affair and is promptly overcome. The term _dislocation_ implies something more permanent as well as complete in both respects. It indicates an absolute and direct separation of articular surfaces of much more than momentary duration and requiring skilled assistance for its reduction. It pertains to articular surfaces which are enclosed within a capsule. The term _luxation_ is synonymous with dislocation. When the condition is evidently partial or incomplete it is often referred to as _subluxation_. As compared with fracture dislocations are about one-tenth as frequent.
Dislocations are described as _compound_ when through a co-existing wound air may enter the cavity of the joint, and as _complicated_ when accompanied by other lacerations or injuries. When unaccompanied by these conditions they are described as _simple_.
To dislocations which result from external violence or from sudden muscular action is given the term _traumatic_. _Pathological_ dislocations are those which are brought about by slow morbid processes, muscle spasm being the most prominent factor in their production. A third variety of dislocations, the so-called _congenital_, do not belong strictly in this class; by common consent the term is applied to congenital abnormalities where, from errors in development, normal emplacements and relations are altered.
The distal bone is the one described as that which is dislocated; thus we speak of dislocations of the forearm upon the arm, of the leg upon the thigh, etc.
Subluxations or incomplete dislocations are frequently accompanied by fracture of a bony prominence, _e. g._, the rim of the acetabulum, the coronoid process of the ulna, etc. The direction in which the distal member of the joint has been displaced is indicated by one of the common terms, as forward, inward. A _consecutive_ or _secondary_ dislocation implies a shifting of position from that at first occupied by the displaced bone end. These injuries may occur at any age, although usually during the more active period of life, from childhood to middle age, when mankind are more subject to injuries.
Certain conditions predispose to dislocations. Abnormalities or previous injury or disease of joint structures figure especially in this respect. A joint already relaxed by hydrarthrosis will exercise a relatively small restraining influence and a subluxation, at least, may easily occur.
The immediate cause is violence, either from without or within, generally the former. This may be _direct_, as from a blow, or _transmitted_, as when the shoulder is displaced by a fall upon the open hand. It occasionally happens that the component bones of a dislocated joint were in a position of extreme flexion or extension at the time of injury. The factors of leverage and spiral tension or wrenching are also important ones. Luxation from _muscular activity_ is occasionally met with; most frequently when the lower jaw is dislocated by the act of yawning or violent laughter. The shoulder has been displaced in a violent effort at throwing or pitching a ball, or in wild gesticulation.
A few individuals have been in the habit of exhibiting themselves whose normal ligament and joint arrangements are so lax that they can voluntarily displace one or more of them and as easily replace them. These may be spoken of as instances of _voluntary_ dislocation.
A joint once displaced may never fully recover its normal degree of tension, and will yield more readily to subsequent similar injuries. In this way there may occur so-called _recurrent_ or _habitual_ dislocations. Expressions of this kind are seen most often in the lower jaw and in the patella.
Actual injury to tissues is to some extent unavoidable. In arthrodial joints the capsule is nearly always lacerated, at least upon one side. In hinge joints both lateral ligaments are likely to be ruptured. It is probable, however, that about the maxillary joints the ligaments may stretch without tearing to any extent. Not only are ligaments torn, but bony prominences are frequently detached, while sometimes there is extensive tearing away of tissue.
In connection with these injuries to joints proper other complications may occur, such as fractures of prominences about joints and epiphyseal separations, or such injuries as compound fracture of the neck of the humerus with dislocation of its head. Furthermore, bloodvessels are occasionally lacerated and nerves are frequently injured. This latter lesion is liable to occur after shoulder dislocations, the head of the bone injuring the circumflex nerve, paralysis of the deltoid being the consequence. This is a feature of the injury, and yet the result has often been unjustly imputed to the physician in attendance. Even a momentary contusion of the nerve may be followed by lasting effects, for which the medical attendant should be held blameless. Other injuries, _e. g._, contusions or lacerations of nerves, may occur about any of the joints.
Dislocations of the spine subject the cord to a special class of injuries which will be dealt with later in this work. In very rare instances the head of the humerus has been forced within the thorax or the head of the femur within the pelvis, these, injuries being practically always fatal.
Compound dislocations rarely occur about the jaw or shoulder. They pertain usually to the joints below. In every case of such character the question will be promptly raised whether a more or less complete exsection of the joint will not be preferable to mere reduction with the ensuing probability of ankylosis. Such injuries will, under all circumstances, require aseptic measures.
So far as _repair_ is concerned, dislocations by themselves are so rarely fatal that there have been but few opportunities for a study of tissue recovery under these circumstances. It is apparent that repair is complete, for after almost any simple dislocation there is restoration of function.
The obstacles to reduction are spasm of muscles pertaining to the injured limb, by which the dislocated bone end is firmly held in its abnormal position, and, in those joints provided with a capsule, the fact that the head of the bone is frequently forced out through a comparatively small opening, through which it is only with the greatest difficulty reduced. It is a part of the manipulation in most cases to enlarge this rent in the capsule, after which reduction is comparatively easy, although impossible until it is accomplished.
Dislocations which have long gone unreduced are called _old_, _inveterate_, or _ancient_. By common consent a period of six weeks has been fixed, beyond which the dislocation is spoken of as old or ancient; up to that time it is usually described as unreduced. In proportion to the length of this period the difficulties of reduction are materially enhanced. So soon as a dislocated joint has been put at rest, _i. e._, fixed by muscle spasm and by the timidity of the patient, the blood which has been poured out will begin to coagulate and conditions are soon favorable for organization of clot and formation of adhesions in abnormal position. In the course of a few weeks these adhesions become strong, and in the course of months they are frequently stronger than the bone itself, which has been disused and has undergone a certain amount of fatty atrophy. Thus it happens that even with well-directed effort the bone will yield before the adhesions, and thus, in spite of every precaution, fracture sometimes complicates the effort to reduce these ancient dislocations.
So generally is this fact now recognized that surgeons do not hesitate to make open incisions for the purpose of separating adhesions and reopening what remains of the capsule in the endeavor to replace the head of a bone. Nor do they hesitate sometimes to cut down upon the latter and exsect rather than run the risk of more extensive injury.
Efforts at reduction under these circumstances subject the patient not only to risk of failure, or of fracture of bone ends, but to rupture of vessels or laceration of nerve trunks. I recall seeing one case of enormous traumatic aneurysm of the axillary artery which was brought about by unsuccessful attempt in this direction.
SYMPTOMS AND DIAGNOSIS OF DISLOCATIONS.
The cardinal indications of a dislocation are _deformity with alteration in contour and position_ of the affected joint. It usually happens that the dislocated bone ends cannot be felt in normal position, but are felt somewhere else in the vicinity. About the shoulder and hip of stout or fat individuals it may not be easy to feel the head of the bone, but unless the case be complicated by a fracture it can usually be detected by aid of anesthesia. The deformity may include a _lengthening or shortening_ of the limb, apparent or real, as well as _abnormal eversion or inversion_, or other peculiarity of position.
Whatever alterations in position appear will be accentuated by _spasm of the muscles_ which pertain to the movement of the affected joint or even of the entire limb. These are usually so tightly contracted as to form a complicating feature of such cases and to lead to that _loss of mobility_ which is diagnostic of every dislocation. Limitation of motion is not entirely a matter of muscle spasm. It is not under voluntary control and subsides only under anesthesia. To some extent motion may be limited by escape of the head of a bone through a small rent in the enveloping capsule, by which it is afterward tightly clasped. This is particularly true of the shoulder and hip. Certain dislocations of the fingers or thumbs are also made more rigid by fixation of the tendons, which become tightly stretched within the neighboring tendon sheaths.
A sort of _crepitus_, which may be easily mistaken for that of fracture, is occasionally detected during the examination of a dislocated joint. It lacks the peculiar grating character of true bony crepitus.
In addition to these features there are certain subjective symptoms, of which _loss of function_ is the most prominent, while _pain_ is a more or less frequent but variable accompaniment, and dependent on the amount of tissue injury or pressure upon nerves. Moreover, the displacement once completely rectified (“reduced”) does not tend to recur, as is the case with fractures.
PATHOLOGICAL AND CONGENITAL LUXATIONS.
The statements made above refer almost entirely to recent and traumatic dislocations.
_Pathological dislocations_ are those which are produced gradually and through the mechanism of disease affecting the joint structures. The head of the bone is gradually drawn out of the acetabulum, in tonic spasm of hip-joint disease, by the continuous action of muscles, the result being the complete displacement of the bone from its original socket, or what is known, at the hip, as the _migration of the acetabulum_, where its upper margin, being softened by disease, is gradually extended and altered, so that the femoral head rests an inch or more higher upon the side of the pelvis than is normal. Pathological dislocations, then, may occur both in the course of the infectious joint diseases as well as in the neuropathic.
_Congenital luxations_ are those which occur from defect in the shape or arrangement of joint structures, permitting a departure from the normal standard. While no joint in the body is exempt from abnormalities of this description, the congenital hip dislocations are those which have attracted attention by their frequency and the disability which they produce.
While the general character of these changes is easily made out by the ordinary methods of examination, coupled with a suitable history, a well-made skiagram will tell at a glance a story which it may take some effort to elicit by other means; hence radiography has here been of great value to the surgeon. Congenital dislocations are devoid of nearly all the features which characterize traumatic dislocations, and their consideration will be found in the chapter on Orthopedics.
_Differential diagnosis as between fractures and dislocations_ is not always easy. Furthermore it is frequently the separation of a prominence by fracture which permits of dislocation, this being
## particularly true of the elbow and the ankle. The extent of a fracture
may seriously complicate the problem of treatment, as, for instance, when the head of the humerus is not only dislocated below the clavicle but separated from the shaft by fracture at the surgical neck. A dislocation made possible only by fracture will not remain reduced as will one which is simple and uncomplicated, while it will display even a greater amount of motility and displacement. Other complications may occur, many of which are common both to dislocations and to fractures in the vicinity of joints, such as lacerations of bloodvessels or nerve trunks, pressure upon the latter, compound injuries with infections, etc.
TREATMENT OF DISLOCATIONS.
The essential requisite of every case is complete reduction or replacement of the dislocated bone end. The earlier this is attempted the better the result. Brief as such a statement is, dislocations frequently offer considerable difficulties, both in reduction and in maintenance in proper position with the necessary physiological rest of the injured part. Thus dislocations of the clavicle, which can hardly occur without considerable injury to the ligaments, may be reduced with slight effort, but are kept in place with difficulty. The simplicity of the after-treatment is proportionate to the difficulty experienced in reduction, so that while “to put the part in place and keep it there” sounds very simple, it will often perplex the ingenuity of the surgeon.
Reduction having been effected, rest is the essential feature of the after-treatment, which should be absolute for a few weeks and relative for many months. Should reaction be extreme, ice-cold applications will afford relief.
The causes which prevent reduction of dislocation are either those attributable to ignorance, carelessness, or failure in diagnosis on one hand, or, on the other, mechanical difficulties, including “button-holing” of the capsule around the expanded end of a bone or the interposition of some of the adjoining tissues. Dislocations of the class referred to above as unreduced or ancient, offer great difficulties, proportionate to their duration, which are due to the formation of adhesions that sometimes take place and become very dense. Judgment, skill, and effort are needed in their management. A dislocation which has become unreducible is only to be treated by arthrectomy and the establishment of a false joint. Nevertheless in a small proportion of cases, especially of the hip and shoulder dislocations, the adhesions which first form gradually relax, and in time there is formed a natural substitute for a joint which may be regarded as a _nearthrosis_, and which will sometimes prove as serviceable as any result afforded by arthrectomy. The duration of time after which reduction is impossible or impracticable varies so widely with different cases that it can scarcely be stated. It rarely is more than a few months and often but a few weeks. It is greater when it is a ball-and-socket joint which is affected.
Nearly everything that has been stated in the previous chapter concerning compound fractures applies here to compound dislocations. They are subject to the same dangers, both of infection and of injury to important adjoining structures. There is the same necessity for aseptic management if the case be seen early, and for antiseptic treatment, including drainage, if seen late. In many instances there is so much liability to subsequent ankylosis that the first treatment may well be made to include an arthrectomy, or the total removal of a small bone, _e. g._, the astragalus. Fortunately compound features are less frequent in dislocations than in fractures.
SPECIAL DISLOCATIONS.
DISLOCATIONS OF THE LOWER JAW.
Unless accompanied by fracture there is but one direction in which the condyle of the inferior maxilla can be dislocated, _i. e._, _forward_. One side or both may be affected, _i. e._, dislocation may be unilateral or bilateral, the latter being more frequent. It is rare during the extremes of age, and most common during middle life. There is considerable variation in the degree of tension of the capsule of the maxillary joint. In some it is so loose that dislocation may occur during the act of yawning or vomiting. Ordinarily it occurs only as an expression of violence from without. By a blow which shall thrust the jaw forward, whether the mouth be closed or open, the ramus may be made to carry the condyle over the articular eminence. The capsule is not necessarily torn, but is always tightly stretched, while as a reflex result the temporal muscle is thrown into a condition of tonic spasm by which the jaw is fixed and firmly held in its abnormal position. This produces the symptoms, then, of a more or less widely opened mouth, with rigidity and inability to close it, with protrusion of the chin and tense contraction of the temporal muscle, which can be easily recognized. When the dislocation is unilateral the symptoms are essentially the same, save that the protrusion is toward the side that is injured.
=Treatment.=--The method of reduction is simple and consists in depressing the angle of the jaw, while, at the same time, the chin is supported and carried both upward and backward. If temporal spasm be not too pronounced the reduction is rather easy and may be effected while the patient is seated in a chair, the surgeon standing in front of him and grasping the jaw with the fingers of each hand, while the thumb is utilized within the mouth to press the angle of the jaw downward and backward. At the same time the fingers should lift the chin. The operator should protect his thumbs by wrapping them with some material in order that they may not be injured by the patient’s teeth. Should muscle spasm offer much resistance it would be well to administer nitrous oxide or one of the other anesthetics, at least to the point of primary anesthesia, with sufficient relaxation of muscle to make reduction easy. When once this has been effected the lower jaw should be bound to the upper and kept at rest for at least two weeks. When this injury has taken place it is likely to recur with much less effort until it becomes almost a habit.
[Illustration: FIG. 338
FIG. 339
Reduction of dislocation of lower jaw.]
There is a condition of relaxation of the capsule and elongation, with abnormal loosening of the interarticular fibrocartilage, peculiar to this joint, by which it has too free play, to such an extent that a clicking sound in its movements may be frequently heard by others than the patient. This condition is either congenital or the result of previous injury, and is one for which little can be done, although this explanation should be afforded to all who suffer from it.
DISLOCATIONS OF THE LARYNX.
The _cartilages of the larynx_ are sometimes displaced as the result of direct violence applied to the anterior region of the neck. Almost any lesion of this character may take place between the independent cartilages of the larynx or the attachments of the larynx to the hyoid. The injury may simply give rise to pain and soreness, or may cause so much interior damage as to be quickly followed by edema of the glottis and suffocation. If the latter be impending a quick tracheotomy should be done, after which time may be afforded for such replacement as may be required, by manipulation, and subsidence of swelling with relief from occlusion of the respiratory tract.
DISLOCATIONS OF THE STERNUM.
The various portions of the sternum, especially the upper and the lower, may be displaced as the result either of direct violence by forcible backward flexion, or by muscular action accompanied by flexion of the trunk and neck. When the latter, it is usually forward; when produced by violence, it is usually backward.
These displacements are sometimes so easily reduced by mere pressure as to make it almost impossible to retain them. At other times anesthesia with firm pressure, accompanied by flexion of the trunk backward or forward, may be required; reduction has been possible sometimes only through incision and by the use of instruments applied as levers, or by the use of a screw driven into one of the fragments, thus affording a handle by which to manage it. Serious dislocations are frequently accompanied by fractures of the ribs or of the sternum. The same fixation of the thorax is required as in fractures of these parts, and should be conducted in the simplest manner possible.
DISLOCATIONS OF THE RIBS.
To displace a rib from its sternal connections requires actual fracture of bone or cartilage. Forward dislocation at its posterior and spinal connection, especially of the eleventh and twelfth ribs, has been described. Considerable effort is necessary for its production, and the case should be treated on its individual merits.
DISLOCATIONS OF THE CLAVICLE.
Either end or both ends of the clavicle may be dislocated. Its sternal end may be thrown in any direction but downward; its acromial end in any direction, although usually upward. Dislocations of the sternal end can only occur in consequence of serious damage to the sternoclavicular ligaments, because of which, and in the absence of a socket, it is extremely difficult to maintain the parts when restored to position. Violent backward traction upon the shoulder permits anterior displacement when the joint is thus weakened. Backward displacement is usually the result of indirect violence when the shoulder is forced forward and inward, while upward displacement is the result of tilting which occurs when the shoulder is violently depressed. Respiration is generally more or less disturbed, while in backward luxations deglutition may be made difficult and painful.
Reduction is not difficult to effect, but extremely difficult to maintain. Pressure in the proper direction, accompanied by traction upon the shoulder, suffices for the former. For the latter there should be a combination of fixation of the shoulder and arm with proper traction, and at the same time pressure upon the end of the clavicle. For all of the clavicular dislocations the dressing and position advised by Dr. Moore, of Rochester, and referred to in the chapter on Fractures as his double figure-of-eight, serves admirably for maintaining the proper position of the shoulder, while pressure can be made by a pad, retained either by adhesive plaster or by some further addition to the dressing itself. (See p. 494.) Acromial dislocation is usually in the upward direction, and is produced by violence upon the shoulder, which has expended itself in rupturing ligaments rather than in fracturing the acromion process. The indication here is to keep the shoulder elevated by any dressing which will accomplish the purpose and the clavicle bound down.
[Illustration: FIG. 340
Position of clavicle in dislocation of sternal end upward.]
Dislocation of _both ends_, _i. e._, complete loosening of the bone, occurs occasionally, in which case the indications already given are reinforced, while the difficulties of treatment are considerably aggravated. Here the shoulder should be kept upward, outward, and backward, and the clavicle retained by pressure or some other means.
=Treatment.=--Clavicular dislocations yield fair results to intelligent treatment. Ideal results are difficult to secure without coöperation on the part of the patient. Functional results, however, are usually satisfactory.
DISLOCATIONS OF THE SHOULDER-JOINT.
The upper end of the humerus is attached to the margin of the glenoid cavity by a capsule which has a certain degree of elasticity, and which resembles a short section of a sleeve or a cuff. It is sufficiently loose to permit a wide range of motion, and were it not for the acromial process above it there would be as much motility in the upward direction as in any other. It is not the capsule which keeps the articular surfaces together, but the tension of the muscles which are wrapped around the shoulder-joint, all of which contribute to this effect. The glenoid cavity is made a more complete socket by a fibrocartilaginous rim. Thus a certain degree of subluxation or displacement may be permitted without very serious damage to this rim and capsule, but a complete dislocation is hardly possible without more or less laceration. The prominence and exposure of the joint and its natural freedom of motion help to account for the fact that more than half of all dislocations occur here, and that this rarely ever occurs in children or in the aged, in whom the violence which may be expanded produces either epiphyseal separations or fractures of the surgical neck. The relation of structure to function also accounts for their far greater frequency (_i. e._, four to one) in men than in women. The influence of atmospheric pressure should not be forgotten, as in the shoulder this affords a force of some fifty pounds, and in the hip of nearly double that amount, of pressure.
[Illustration: FIG. 341
Subcoracoid.
Subclavicular.
Subspinous.
Subglenoid.
Dislocations of the head of the humerus. (Erichsen.)]
[Illustration: FIG. 342
Relation of circumflex nerve to the head of the humerus, explaining mechanism of deltoid paralysis. (Marion.)]
For convenience of description, and in the order of their frequency, shoulder dislocations are referred to as _anterior_, _downward_, _posterior_, and possibly _upward_, when combined with acromial fracture. Anterior displacements vary in degree, so that they are described as _subcoracoid_ or _subclavicular_. Complete displacement in this direction can only occur through a rent in the anterior portion of the capsule, while the subclavicular muscle is pushed away or torn. The nearer the head of the bone rests to the sternum the greater the amount of laceration of the capsule, while its posterior portion is either stretched tightly or torn. In aggravated cases the tendon of the biceps is also torn out of its groove (Figs. 341, 343 and 344).
[Illustration: FIG. 343
Subclavicular dislocation. (Lejars.)]
[Illustration: FIG. 344
Subcoracoid dislocation. (Lejars.)]
In the downward or _subglenoid luxations_ the capsule is lacerated lower down. These displacements occur when the shoulder has been dislocated with the arm in the extended and elevated position. Here the head of the humerus is found in the axilla, resting against the border of the scapula, and the axillary structures, especially the circumflex nerve, usually sutler, while the external rotators are either ruptured or their insertions detached (Fig. 345).
[Illustration: FIG. 345
Subglenoid dislocation. (Lejars.)]
The posterior or _subspinous_ dislocation is the least common of all. In its production the arm is apparently adducted and the elbow raised. Here the humeral head is found beneath the posterior surface of the acromion or beneath the spine of the scapula (Fig. 341).
=Symptoms.=--The indications of shoulder dislocation are _pain_; _flattening of the shoulder_; _undue prominence of the acromion_; _depression opposite the glenoid cavity_, with loss of the rounded contour due to the presence therein of the head of the humerus; _appearance of a more or less globular mass_ in the position now abnormally occupied by the head of the humerus; _change in the axis_ of this latter bone; _inability to bring the elbow to the side_; more or less complete loss of function, and more or less spasm of the muscles about the joint. Owing to the fact that the thorax presents a curved or warped surface, to which a straight line can be tangent only at one point, it results that the _hand of the injured side cannot be made to wrap itself over the opposite shoulder while its elbow still touches the chest or side_ (Dugas’ test).
=Diagnosis.=--As between fracture and dislocation the surgeon may be greatly helped by deciding that the head of the humerus is still in its proper position; that the deltoid is not flattened as in dislocation; that the arm is shortened rather than lengthened; that motility is increased rather than diminished; that bony crepitus is usually obtainable, and that replacement, which may be comparatively easily secured, is maintained only so long as the parts are held in position by the operator’s hands. An additional sign of value is the fact that a straight edge cannot ordinarily be made to touch the tip of the acromion and the external condyle of the humerus at the same time, because of the protrusion caused by the presence of the head of the humerus in its socket. When the straight edge can be so applied it must be either because the head of the bone is out of the socket or the upper end of the bone broken. A still more crucial test which should, however, only be applied when others prove unsatisfactory, may be furnished by passing a sterilized hat-pin through the sterilized skin over what seems to be the displaced head of the bone and into the globular mass. Rotation of the humerus will then cause its end or head to make an excursion which will be quite distinctive.
[Illustration: FIG. 346
Exhibits a subcoracoid dislocation and the position of the patient in his endeavor to find relief from pain. (Mudd.)]
=Treatment.=--Prompt reduction is the only treatment for shoulder or other dislocations. This may be first attempted without anesthesia. Should muscle spasm prevent easy reduction it should be relaxed by an anesthetic, for which purpose nitrous oxide will often suffice. In the forward or forward and downward dislocations it will sometimes be sufficient to simply make firm traction in a direction obliquely outward and upward, with rotation. When this is insufficient it may be assumed that there is more or less laceration of the capsule and entanglement of the head of the bone, as well as that it is caught around the border of the glenoid cavity, against which it is firmly held.
The above simple maneuver failing, the luxation is to be reduced by a more scientific manipulation, in which traction figures largely, the method now generally in vogue being that suggested by Kocher, by which rotation and leverage are added to traction, and a minimum of power made to do a maximum of good. Kocher’s method is especially applicable to the anterior displacements. It consists of a triple manipulation whose three stages are portrayed in Figs. 347 to 349. The first procedure is to flex the forearm to a right angle with the arm, apply the former firmly to the side, and then, while keeping the elbow at the side, forcibly rotate the limb outward until the forearm points away from the body (Fig. 348). This having been done the arm is abducted and the elbow moved upward until the limb is in the horizontal plane of the shoulder, the scapula being held firmly during these movements, as shown in Fig. 348. After the arm has been brought to the level of the shoulder it is rotated inward and brought downward by a process of circumduction, the elbow being made to describe some part of the arc of a circle as it comes down. The displaced head should slip into place during this movement, and will do so unless the capsular tear is too small. In that case the movements should be repeated, perhaps with more force, until the opening is sufficiently enlarged to permit the button-hole in the capsule to slip over the head of the bone.
[Illustration: FIG. 347
First position in Kocher’s rotation method.]
[Illustration: FIG. 348
Arm is being carried forward and upward toward second position.]
[Illustration: FIG. 349
Completion of third movement in Kocher’s method.]
This method of manipulation, with such modification as circumstances may require, or such addition as pressure with the hand or fingers of the assistant, has superseded all the older more crude and forceful methods, and proves sufficiently applicable for all cases. It is assumed that the operator has sufficient judgment to modify any method to fit the exigencies of a given case, else he should not proceed with it. For instance, in the axillary dislocations upward traction affords valuable assistance. In the subspinous form the arm is raised to a level while extension is made upward and forward. In other words, all these methods depend upon the combination of traction, rotation, and leverage. The old method of Astley Cooper, with the foot in the axilla, the shoe having been removed, coupled with traction upon the arm and swaying movements, combined with rotation, abduction, and adduction, may be made effective, but is not nearly as elegant as the simpler manipulation above described. On the other hand, old, unreduced dislocations, complicated with adhesions, are often exceedingly difficult.
In rare instances dislocations several months old have been reduced after adhesions have been broken up by more or less violent manipulations. When forcible efforts of this kind prove futile fair restoration of function may be obtained by maintaining regular motion, at first passive, later active, to prevent reformation of adhesions, the head of the bone gradually forming a new and false socket for itself. Finally, the method of excision can be employed should occasion demand. The experience of a number of surgeons has shown that in old cases, or those impossible of reduction by justifiable force, an open division of the joint, with severance of those tissues which prevent reduction, may be profitably, safely, and satisfactorily practised. Porter and McBurney, among the American surgeons, have devised a corkscrew instrument which may be driven into the head of the bone, by which manipulation after arthrotomy is materially facilitated.
The _simultaneous occurrence of fracture and dislocation_ has been treated of in the previous chapter. When difficulty presents the best result will be obtained by open incision, replacement of the head of the humerus, and fixation of fragments by sutures, wire or otherwise. If seen late the upper fragment should be removed. The possibilities of aseptic surgery have led to the abandonment of the old method of first permitting the fracture to unite and then attempting to reduce dislocation.
Physiological rest is the essential feature of the after-treatment of all these cases, a sling and a retentive bandage being sufficient for the purpose. Function should be restored by an increasing degree of motion.
One of the most serious complications of shoulder dislocations is _deltoid paralysis_ from injury to the circumflex nerve. The momentary pressure of the head of the bone upon the nerve is sufficient to more or less permanently impair its function. In its medicolegal aspect it should always be maintained that the surgeon is never to blame for the accident, and is only to some degree blamable in case he has failed to diagnose the dislocation so soon as opportunity was afforded and has thus permitted prolonged pressure to possibly intensify the effect which has already been produced by the injury.[42]
[42] The shoulder is liable to numerous injuries that produce disability. Pain in some of these conditions may be almost constant and spread upward to the neck and be aggravated by even passive motion. Loss of power varies from moderate paresis to complete paralysis. When the circumflex nerve is especially involved it is the deltoid which shows the effects. More severe injuries may involve the muscles of the arm and the forearm. Muscle atrophy may be greater than can ordinarily be accounted for by mere disease. In rheumatic patients a dry synovitis may be added to the other complications. Most of these features are due to traumatic neuritis. When aggravated they may result from rupture of nerves or cicatricial formations around them. The best treatment consists of immobilization for three or four weeks to favor nerve repair, counterirritation, especially with the flying cautery, over the roots of the branchial plexus, with massage, electricity, and even deep injections of strychnine to stimulate the paralyzed muscles. When paralysis is persistent and scar tissue seems to press upon nerves, exposure of the plexus and freeing its branches from all source of pressure will be necessary.
DISLOCATIONS OF THE ELBOW.
The irregularities of the elbow-joint have permitted a complicated dovetailing of its component parts which would seem to make dislocations almost impossible without fracture. Nevertheless, and especially in the tender years of childhood, both bones may be dislocated in either direction, or either bone of the forearm alone in any direction save toward the other. Diagnosis will be greatly aided by observance of the anatomical facts stated in the section on fractures of the elbow-joint and by an estimate of the relative positions occupied by these bony landmarks. When, however, intense swelling prevents this then we should either wait for its subsidence or depend upon a skiagram.
The most common dislocation is that of _both bones backward_, one of the possible consequences of a fall upon the extended arm and palm of the hand. The coronoid process may rest beneath the joint end of the humerus, making the dislocation incomplete, or back of it, making it complete. If the coronoid process has been broken off the dislocation can be made and reduced as often as desired. The fan-shaped lateral ligaments are always more or less lacerated. The arm will be partially bent and there will be prominent deformity upon the posterior aspect of the joint while the axes respectively of the arm and the forearm will be somewhat disturbed. Usually the lower end of the humerus can be felt in front of the normal situation of the elbow-joint (Figs. 350, 351 and 352).
Reduction is more or less easily accomplished by traction with an easy movement, by which the upper end of the forearm shall be directed toward its proper position.
_Lateral displacements_ result also from falls in extreme positions. Lateral dislocations are rare and the result of violence, and may compel amputation. In these cases the lateral diameter of the joint is markedly increased, while the normal relation of the condyles to the olecranon is greatly altered. In these cases movement is painful and limited.
[Illustration: FIG. 350
Backward dislocation of both bones. (Lejars.)]
[Illustration: FIG. 351
Outward displacement of both bones. (Lejars.)]
The _ulna alone_ may be dislocated backward, in which case the orbicular ligament must be lacerated and the upper ends of the adjoining bones forcibly separated. The olecranon will present back of its proper position, while the head of the radius will rotate where it belongs.
[Illustration: FIG. 352
Dislocation forward and outward of head of radius. (Lejars.)]
_Anterior dislocation of both bones_ is exceedingly rare unless complicated by fractures of the olecranon. When thus injured the forearm is lengthened and fixed. The posterior surface of the humerus here has only a skin covering, the condyles are bulging, the olecranon fossa empty, and the upper ends of the forearm bones felt in front of the elbow.
The _head of the radius_ alone may be displaced in any direction save toward the ulna. The _forward_ dislocation is the most common, which may be produced by a fall upon the overextended and pronated hand. The orbicular ligament here is lacerated or the head of the radius is slipped out of it. In the latter case it may be difficult to replace it. When dislocated _backward_ the capsule is torn posteriorly as well as the orbicular ligament (Fig. 353).
[Illustration: FIG. 353
Position of the bones in an old unreduced dislocation forward of the radius. (Erichsen.)]
=Treatment.=--The treatment of elbow dislocations is based upon general and but slightly differing principles. It consists of a combination of traction with sufficient force, made with one hand, while with the other pressure should be made upon one or both bones in the desired direction; at the same time by a combination of swaying and rotary movements more or less massage may be given to the parts, by which complete reduction may be more easily effected. Anesthesia is nearly always necessary, not alone for the relief of pain, but to produce muscular relaxation, by which manipulation is materially assisted.
A peculiar form of dislocation of the head of the radius in young children has received considerable attention. It is produced by a firm pull upon the wrist or forearm, as in lifting or jerking a child by the forearm or hand. Pronation of the hand is usually a feature of the injury. It is probable that the head of the bone is pulled out of the orbicular ligament and displaced forward. The forearm is slightly flexed, movements of the elbow are very free, except that supination of the forearm meets with resistance. The displacement is rectified by a forced supination with traction. An epiphyseal separation of the head may simulate this injury. Such cases necessitate a few days’ rest in a splint, with the arm flexed and supinated, although recovery often occurs without particular restraint.
DISLOCATIONS OF THE WRIST AND HAND.
Wrist dislocations are rare, the _posterior_ being more frequent than the _anterior_. It simulates the deformity of a Colles fracture, and is produced in a similar way. The deformity is more marked, the outlines of the various bones more distinct, except in front, where they may be masked by the flexor tendons. There is no alteration in the relations of the styloid processes. The _forward_ dislocation may possibly simulate Smith’s fracture, the symptoms being the reverse of those above mentioned.
Firm traction, with pressure in the proper direction upon the carpus, will suffice for reduction of these cases. The subsequent dressing may be practically that of a Colles fracture.
The _lower ends of the ulna and radius_ are sometimes dislocated from their proper relations. Reduction is easy, but rest and restraint are required for some time until the ligaments have recovered their tonus.
Of the _carpus_ the _os magnum_ is the only one likely to be displaced, it being occasionally forced backward so that it forms a projection on the dorsum of the hand. It requires extreme force to displace the carpal bones, enough frequently to produce other injuries at the same time, some of which may be compound. A carpal bone which cannot be reduced to position by pressure may be safely removed through an incision.
Of the carpometacarpal dislocations, the _thumb_ is the most frequently displaced, usually in a backward direction. Traction and pressure suffice for its reduction. When the bone is forced forward it is usually as the result of direct violence. Wherever the base of the bone may rest it is easily detected, while pressure with traction suffices for its replacement.
Of the dislocations of the _phalanges_ upon the metacarpus those of the thumb are the more frequent. This may occur as the result of a fall, by which the thumb is forced backward into a position of hyperextension. Nearly all of these dislocations are accompanied by a rupture of capsule. Those of the thumb are difficult of reduction; this appears to be due to the tendons of the short flexor, which surround the head of the metacarpal bone. The sesamoid bones also furnish a source of difficulty, while the long tendons, when contracted by their respective muscles, increase it (Fig. 354).
[Illustration: FIG. 354
Metacarpophalangeal dislocation.]
Treatment, especially of the thumb dislocations, is facilitated by first exaggerating the abnormal position, then making traction and pressure in the proper direction at the same time. Special forceps have been devised for seizing and holding the digits, or a clove-hitch can be thrown over the thumb or finger. Extension should not be first made in the axis of the metacarpal bone, but rather _at an abrupt angle to it_ in order to relieve the expanded phalangeal end. The majority of writers concede that in some cases reduction is practically impossible. When effort has proved futile the parts should be sterilized and incised, the incision being utilized for open reduction or for excision, as deemed best.
Dislocations of the other phalanges are usually easily recognized and treated by traction and pressure.
DISLOCATIONS OF THE HIP.
Hip dislocations constitute about 5 per cent. of the total. As they are produced by violence they are much more frequent in men, and occur mostly between the ages of twenty and fifty years. Before the twentieth year epiphyseal separations often take place, while after the fiftieth year violence will usually break the neck of the femur. Nevertheless dislocations may occur at any age. The hip is a ball-and-socket joint, with a deep socket still further extended by cartilage, in which the head of the bone is not only retained by the ligamentum teres, but by atmospheric pressure, which in the natural state furnishes a factor of perhaps one hundred pounds. The strongest muscles and tendons of the body envelop the joint. When dislocation occurs the capsule is usually torn along its inferior aspect. The limb is usually in an extreme position, or it would require more violence to tear the head from the socket. The anterior dislocations occur during abduction without outward rotation; posterior dislocations occur during flexion. Thus when a person is stooping over in work and a heavy weight falls upon the back the head of the bone is more easily pushed backward, especially if the feet be close together.
While hip dislocations are classified for convenience, and because of their final form, the head of the bone may rest upon almost any segment of the margin of the acetabulum, though within a short time it will assume a position justifying a designation as _anterior_ or _posterior_, meaning thereby in front of or behind Nélaton’s line. This is, moreover, a convenient distinction, as the symptoms vary between the two groups. Another classification is into the _forward_, the _backward_ or _backward and upward_, and the _downward_, which are again referred to as _iliac_, _ischiatic_, _dorsal_, and _supracotyloid_ among the posterior, and _perineal_, _obdurator_, _suprapubic_, etc., among the anterior (Fig. 355).
Allis, however, has simplified the subject by showing that all forms of dislocation escape primarily from the lower segment, shifting their position later either upward or downward. He classifies them as follows:
1. Lower thyroid. } All present the general characteristics of 2. Middle thyroid.} adduction and rotation outward. 3. High thyroid. }
1. Low dorsal. } All present the general characteristics of 2. Middle dorsal. } abduction and rotation inward. 3. High dorsal. }
The relation of the so-called Y-ligaments to the successful reduction of these dislocations, as well as to their formation, is of considerable importance.
[Illustration: FIG. 355
Upward and somewhat backward on dorsum ilii.
Backward toward sciatic notch.
Downward into foramen ovale.
Forward and upward on the pubic bone.
Dislocations of the head of the thigh bone, according to Astley Cooper’s classification. (Erichsen.)]
Fig. 356 illustrates the manner in which this ligament receives its name, it being simply a reduplication of fibers which strengthen the capsule and which are arranged in the shape of an inverted Y. No matter how serious the injury it is seldom entirely detached. While it prevents too great displacement it is of special service in that it may be made to serve as a fulcrum for the leverage required in certain manipulations. American surgeons are entitled to the credit for the establishment of the importance of this ligament in this consideration, and while Bigelow’s name is most prominently mentioned, the names of Gunn, of Chicago, and Reid and Moore, of Rochester, New York, deserve almost equal prominence, not only for their anatomical studies, but for working out the entire method of manipulation which has completely supplanted the old and more violent methods in which the use of pulleys and tackle was not infrequent. The Jarvis “adjuster,” a powerful mechanism, which was formerly employed for this purpose, is not now seen except in museums.
[Illustration: 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.
[Illustration: FIG. 357
Anterior dislocation of head of femur. (Lejars.)]
[Illustration: FIG. 358
Posterior dislocation of head of femur. (Lejars.)]
This classification into the anterior and posterior seems to the writer to simplify the general subject and to be serviceable for its
## particular purpose and place. Inasmuch as anesthesia is nearly always
required for these injuries it may be expected to clear up difficulties in diagnosis by its aid.
=Treatment.=--Through the anatomical researches of the surgeons above named, as well as those of Allis and others, the method of reduction of hip dislocations is practically always that by _manipulation_, and is in nearly every instance commenced with _flexion_. In fact a considerable number of backward dislocations can be reduced almost alone by flexion and rotation with traction, the patient being upon his back, preferably upon the floor, and the surgeon standing over him. While anesthesia is not necessary in all cases it affords sufficient assistance to justify its general employment.
In the backward dislocations, the patient and surgeon being in position as above, it is well to employ the Kocher method, which consists of (1) inward rotation, by which the capsule is relaxed and the head of the bone carried from the pelvic surface; (2) flexion to a right angle, preserving the existing adduction and inward rotation; (3) traction, by which the capsule is made tense and the head of the bone raised to the level of the socket; (4) outward rotation, by which the posterior part of the capsule and the outer band of the Y-ligament are tightened and the head turned forward into the socket.
[Illustration: FIG. 359
FIG. 360
FIG. 361
FIG. 362
Illustrating various types of dislocation at the hip. (Lejars.)]
During the practice of this or any other method the pelvis should be firmly held in place by assistants, who may seize it with the hands and hold it down. If the patient lay upon the table the pelvis may be bound to it. The surgeon may need help in making a sufficient degree of traction. This can be furnished by a strong loop passed under the patient’s knee and over the surgeon’s shoulders, the hands thus remaining free for manipulation, traction being the most important feature.
Stimson accomplishes the same purpose by placing the patient, face downward, upon a table, the dislocated limb hanging downward as represented in Fig. 363. Traction is here partly affected by the weight of the limb, while in some instances the surgeon has to wait only for the muscles to relax and the bone to resume its place without much further effort than a slight rocking or rotation. Stimson claims that this often succeeds without anesthesia, and sometimes so quietly that there is scarcely any jar or sound to indicate the effection of the reduction.
[Illustration: FIG. 363
Reduction of dorsal dislocation of the hip by the weight of the limb. (Stimson.)]
In those forms of dorsal dislocation which are accompanied by _eversion instead of inversion_ it is necessary only to convert them into the ordinary dorsal type before proceeding as above.
In high displacement of the head of the bone traction should be made in the extended position, by which the head will be brought back of the acetabulum, and then proceed as above.
Of the _anterior_ dislocations the obturator is perhaps the more common, while for its reduction the following directions usually suffice: The limb is flexed toward the perpendicular to disengage the head of the bone, then rotated inward and adducted while the knee is carried to the floor. As Bigelow suggested, in this maneuver we may need the aid of a towel passed around the upper part of the thigh, an assistant making upward and outward traction while the operator is bringing the limb downward. Inward rotation is likely to transform the dislocation into a posterior one. On account of this fact, Kocher would give the following advice: (1) Flex the thigh to a right angle with the pelvis, preserving abduction and outward rotation until (2) traction is made, by which the posterior part of the capsule is tightened and the head brought nearer the socket; then (3) forcible outward rotation is made, which should bring the head upward and backward into place.
A _perineal_ dislocation is usually accompanied by laceration of the capsule. This will permit of easy reduction, which can probably be effected by traction in the axis of the limb in its abnormal position and by direct pressure, with some rotation or rocking.
The _pubic and suprapubic_ dislocations require forcible flexion with traction in the axis of the limb, followed by inward rotation and circumduction of the knee. Some of these maneuvers are illustrated in Figs. 364 and 365.
So of the other dislocations of the hip; an application of principles similar to the above, coupled with such assistance as may be afforded by manipulation, practised by the operator, or by traction, with the help of an assistant, will usually suffice.
If a general rule could be formulated covering all cases it would be of great assistance. I have been in the habit of quoting a rule of this character, which I first saw mentioned in the American edition of Bryant’s _Surgery_, edited by Roberts, to the following effect: (1) Flex the leg on the thigh and the thigh on the body; (2) carry the knee as far as it will go in the direction in which it already points; (3) carry the knee to the extreme in the opposite direction and combine this movement with circumduction and traction. In the backward dislocations these manipulations should be accompanied by traction made with one of the operator’s hands in the popliteal space. In the anterior displacement backward pressure instead of traction can be made by pressing upon the knee. I have found this an admirable working direction.
[Illustration: FIG. 364
Reduction of a dorsal dislocation of the hip by traction. (Erichsen.)]
[Illustration: FIG. 365
Reduction of a dislocation by rotation. The thigh is flexed, slightly adducted and rotated inward, as in the first stage of reduction of a dorsal dislocation. (Erichsen.)]
The _after-treatment_ of hip dislocations consists mainly in rest and quiet. These should be enforced, at least by a binder around the pelvis, and, if necessary, a starch or plaster-of-Paris protection. The anterior suspension splint affords a comfortable and efficient method of treating these cases after the first few days. (See Fig. 322.) Very little liberty should be allowed the patient until the expiration of the first month.
=Ancient and Unreduced Dislocations.=--The longer a hip dislocation is allowed to go unreduced the more difficult is its replacement. The expiration of six weeks will usually make a hip reduction very difficult, while after a lapse of three or four months it becomes wellnigh impossible. The longer a limb is disused the more do its osseous structures atrophy. Therefore a fracture of the neck of the femur or upper end of the shaft may occur in attempting to reduce an old luxation. The most marked obstacles are offered by formation of adhesions about the femoral head in its new position, and the shrivelling or change in shape of the capsule, whose opening may be distorted or obliterated, so as to make reëntrance impossible within it of the head of the bone.
Other things being equal, then, more force and wider range of motion are necessary in reducing the older dislocations, while success may be attained only by the expenditure of wellnigh all the muscular energy of a powerfully built man. Attempts prolonged too far produce serious laceration, with hemorrhages, which tend to encourage new adhesions in case of failure. If a dislocated hip cannot be reduced by any apparently safe procedure the operator should decide whether to leave it, in the hope of securing a false joint, or to cut down the parts and make such further division of tissues as may be necessary. Should this be contemplated it implies, of course, that each case should be adjudged upon its merits.
DISLOCATIONS OF THE PATELLA.
By various contractions of the quadriceps muscles the patella may be displaced _outward_, it being practically slipped over the external condyle. The same result may be produced by a blow from the inward direction and in the extended position of the limb. These displacements may be _complete_ or _incomplete_; in the former case the flat plane and inner edge of the bone are directed forward instead of sidewise. _Inward_ displacements are unusual and usually produced by direct violence. Such previous disease as shall have weakened the capsule, or caused its distention, permits these dislocations to occur with a minimum of violence. In fresh cases the capsule is usually torn.
_Reduction_ is easily effected by lifting the limb, thus relaxing the quadriceps muscle and making pressure and manipulation in the indicated direction. An anesthetic may be given if thought admissible.
When the limb is partially flexed, and a blow is received on the edge of the patella directly from the front, it is occasionally rotated on its tendinous axis, so that without being displaced from its position in front of the condyles its articular surface looks inward and it rides the knee upon its edge. This is referred to as _vertical rotation_. It is relieved and replaced by suitable manipulation, a feature of which may be sudden and forcible flexion with external pressure.
The patella once displaced the joint structures are left more or less permanently impaired, and recurrence of the lesion is by no means uncommon. Some individuals, the young especially, have the habit of “slipping the knee-pan,” this implying that at least partial displacement occurs easily with comparatively slight provocation. Sometimes children become so accustomed to this that they learn how to care for it themselves.
=Treatment.=--After every knee dislocation protection should be afforded for a considerable period. In habitual dislocations it may be justifiable to make lateral incisions and to excise an elliptical portion of the capsule, by which its dimensions may be reduced and its undue laxity abolished.
DISLOCATIONS OF THE KNEE.
The _head of the tibia_ is occasionally displaced as the result of accident, though frequently this is the result of joint lesions. A traumatic dislocation can scarcely occur without considerable injury and internal derangement of the joint structures proper. _Anterior_ dislocation may occur when the femur is forced backward or the leg forward in severe accidents. Here the popliteal vessels may undergo such pressure and injury as to constitute a serious complication. The _backward_ dislocations are less common, though likewise the result of violence. It matters not whether the thigh be fixed and the leg forced in either direction, or whether the leg be caught and fixed while the body is made to displace the femur; such injuries are not likely to be mistaken. They are likely, also, to be accompanied by _displacement of the semilunar cartilages_. _Lateral_ dislocations are practically the result of force, often combined with torsion. Injury to the lateral ligaments, usually extensive laceration, should accompany them.
Dislocations of the knee are more or less easily reduced, in theory at least, by forcible traction and manipulation, and with the aid of an anesthetic. Absolute rest, preferably in a plaster-of-Paris splint, is requisite.
The _semilunar cartilages_ are occasionally torn loose and more or less displaced, either toward the notch or toward the exterior of the joint. A cartilage so displaced will project, as a rule, at the upper margin of the tibia. These injuries may occur alone or as a complication of more serious forms described above.
=Symptoms.=--These displaced cartilages produce symptoms simulating those of movable bodies in the joint--that is, disability depending upon the extent of the original injury and the direction of the displacement. The movable cartilage may be either pulled into place by flexion or manipulated until it returns there, but will frequently reappear when the leg is straightened. It sometimes becomes so entangled in the joint as to cause almost complete disability. When movable anteriorly it may be recognized along the upper border of the tibia. The same sudden disability may be produced here as when there are other loose or movable bodies in the joint. The patient may be able to indicate that there is something movable in the joint.
=Treatment.=--Non-operative treatment consists in sufficient limitation in the motion of the joint with abstention from use of it. In cases not amenable to non-operative measures the joint may be opened and the cartilage fastened in place to the head of the tibia either with absorbable or non-absorbable sutures.
=The Fibula.=--The upper end of the fibula, although firmly bound to the tibial head, may be dislodged by direct or indirect violence. Forcible inward rotation of the foot, in full extension, will sometimes displace it _forward_, while forcible traction on the biceps may dislocate it _backward_. Displacements at this joint may occur when the leg bones are broken, while when the tibia alone is broken and shortened _upward_ displacement may occur in consequence. Should displacements be discovered it will not be difficult by traction upon the foot and leg, in the normal direction, and by pressure to replace them. The backward displacement is the more unstable of the two. The _lower end_ of the fibula is by itself rarely dislocated or distorted except in connection with violent sprains, accompanied by the laceration of ligaments or fracture of one or both bones.
DISLOCATIONS OF THE FOOT.
_Backward_ and _forward_ displacements of the foot are possible without fracture; as, for instance, when violence is applied to the leg after the foot is caught and fixed. Even here, however, the lateral ligaments must suffer partial or complete laceration, while one or both malleoli may be broken. The most frequent displacements of the foot are those which accompany and are permitted by fractures of the lower part of the leg, notably that originally described by Pott, with its troublesome form of bone lesions. An _inward_ dislocation of the foot is described as produced by extreme supination and adduction.
It is necessary in studying these injuries to the ankle region to make out the existence of fracture, if any be present, as the treatment hinges largely upon such complication.
The _astragalus_ may be dislocated from its relations with the lower ends of the leg bones, as the result of wrenches or twists or of violent injuries, as falls or blows upon the feet. When displaced it is nearly always forward. A backward dislocation is exceedingly rare. The rest of the foot itself is sometimes dislocated backward beneath the astragalus, although some portion of its lower surface still remains in contact with the upper surface of the calcis. These displacements occur in consequence of combined torsion and excessive violence. The foot here will be shortened anteriorly. No matter in what direction the astragalus may be displaced it is easily recognized.
=Treatment.=--Reduction of ankle-and-foot dislocations accompanied by fracture is not a difficult matter, although their retention may be; but astragalus dislocations which are complicated are usually difficult of replacement. They will require relaxation of muscle tension by anesthesia or tenotomy and forced manipulations. When accomplished good function results. Better results may be obtained by exsection.
Many of these more serious forms of dislocation are _compound_. In such cases removal of the astragalus, or a more or less typical resection of the ankle-joint, may be judicious. In crushing injuries, either primary or secondary amputation may be necessary.
In general it may be said of the bones of the foot that one which resists reasonable effort at reduction, when displaced, should be removed. Various displacements of the tarsal bones, as the result of direct violence, may occur, as well as of the metatarsal and phalanges. Many of them may be reduced by judicious pressure and manipulation, but the violence which inflicts the displacement will frequently make the injury so compound that excision or partial amputation may be necessary.
## PART VI.
SPECIAL OR REGIONAL SURGERY.
##