#Gun-shot Injuries of Bone.#--Fractures resulting from the impact of bullet or fragments of sh.e.l.l are of necessity compound, and are usually infected from the outset by organisms carried in by the missile or by portions of clothing or other foreign material. Not infrequently the missile lodges in the bone.
[Ill.u.s.tration: FIG. 7.--Excessive Callus Formation after infected Compound Fracture of both Bones of Forearm--result of gun-shot wound.
Fusion of Bones across Interosseous s.p.a.ce.]
The extent of the injury to the bone varies infinitely, from a mere chip or gutter-shaped wound to complete pulverisation of the portion struck. The fracture is of the comminuted and fissured variety, the cracks radiating from the point of impact and extending for a considerable distance, sometimes even implicating the articular surface of the bone some inches away. In comminuted fractures of the shafts of long bones there is often a large wedge-shaped fragment completely isolated from the rest, and in the presence of infection this may form a sequestrum. Healing is often delayed by the separation of sequestra, which takes place slowly, and union is attended with excessive formation of callus. When a considerable section of the shaft has been lost, want of union, fibrous union, or the formation of a false joint may result.
The treatment is carried out on the same lines as in other forms of compound fracture, except that mention should be made of the irrigation method of Carrel, found to be the most potent means of overcoming the a.s.sociated infection.
SEPARATION OF EPIPHYSES[1]
[1] We do not employ the term "diastasis," which has been used in different senses by different writers.
In young subjects before the bones are fully developed the epiphyses may be separated from the diaphyses. The use of the X-rays has added greatly to our knowledge of these lesions.
It is useful to remember that in the upper extremity the epiphyses in the regions of the shoulder and wrist, and, in the lower extremity, those in the region of the knee, are the latest to unite; and that it is in these situations that growth in length of the bone goes on longest and most actively (twenty to twenty-one years). Injuries of these epiphyses, therefore, are most liable to interfere with the growth of the limb.
An epiphysis is nourished from the articular arteries and through the vessels of the periosteum.
_Pathological Separation of Epiphyses._--There are certain pathological conditions, such as rickets, scurvy, congenital syphilis, tubercle, suppurative conditions, and tumour growths, which render separation of the epiphyses liable to occur from injuries altogether insufficient to produce such lesions under normal conditions.
#Traumatic Separations.#[2]--Speaking generally, it may be said that injuries which in an adult would be liable to produce dislocation, are in a young person more apt to cause separation of an epiphysis.
Indirect violence, especially when exerted in such a way as to combine traction with torsion,--for example, when the foot is caught in the spokes of a carriage wheel,--is the commonest cause of epiphysial separation. Direct violence is a much less frequent cause. Muscular action occasionally produces separation of the epiphyses--for example, the anterior superior iliac spine, the small trochanter of the femur, or the upper end of the fibula.
[2] We desire here to acknowledge our indebtedness to Mr. John Poland"s work on _Traumatic Separation of the Epiphyses_.
[Ill.u.s.tration: FIG. 8.--Partial Separation of Epiphysis, with Fracture running into Diaphysis.]
[Ill.u.s.tration: FIG. 9.--Complete Separation of Epiphysis.]
[Ill.u.s.tration: FIG. 10.--Partial Separation with Fracture of Epiphysis.]
[Ill.u.s.tration: FIG. 11.--Complete Separation with Fracture of Epiphysis.]
The majority of separations take place between the eleventh and the eighteenth years, chiefly because during this period the injuries liable to produce such lesions are most common. They do not occur after twenty-five, because by that time all the epiphyses have united.
In females this form of injury is rare, and almost invariably occurs before p.u.b.erty.
The following are the most common seats of separation in the order of their frequency: (1) the lower end of the femur; (2) the lower end of the radius; (3) the upper end of the humerus; (4) the lower end of the humerus; (5) the lower end of the tibia; and (6) the upper end of the tibia.
_Morbid Anatomy._--In a true separation the epiphysial cartilage remains attached to the epiphysis. As a rule the epiphysis is not completely separated from the diaphysis, the common lesion being a separation along part of the epiphysial line, with a fracture running into the diaphysis (Fig. 8). It is not uncommon for more than one epiphysis to be separated by the same accident--for example, the lower end of the femur and the upper ends of the tibia and fibula.
Epiphysial separations, like fractures, may be _simple_ or _compound_.
Incomplete separations are liable to be overlooked at the time of the accident, but there is reason to believe that they may form the starting-point of disease. Strain of the epiphysial junction--the _juxta-epiphysial strain_ of Ollier--is a common injury in young children.
_Clinical Features._--The symptoms simulate those of dislocation rather than of fracture. Thus, _unnatural mobility_ at an epiphysial junction may closely resemble movement at the adjacent joint, especially when the epiphysis is an intra-capsular one. The relationship of the bony points, however, serves to indicate the nature of the lesion. The degree of _deformity_ is often slight, because the transverse direction of the lesion, the breadth of the separated surfaces, and the firmness of the periosteal attachment along the epiphysial line often prevent displacement. In many cases a distinct, rounded, smooth, and regular ridge, caused by the projection of the diaphysis, can be felt. The peculiar "m.u.f.fled" nature of the _crepitus_ is one of the most characteristic signs. The older the patient, and the further ossification has progressed, the more does the crepitus resemble that of fracture.
Of the subsidiary signs, _loss of power_ in the limb is one of the most constant; indeed, in young children it is sometimes the first, and may be the only, sign that attracts attention. _Pain_ and _tenderness_ along the epiphysial line are valuable signs, particularly when the lesion is due to indirect or muscular violence and there is no bruising of soft parts. Localised _swelling_, accompanied by _ecchymosis_, is often marked; and the adjacent joint may be distended with fluid.
As distinguishing this injury from a dislocation, it may be noted that in epiphysial separation there is no snap felt when the deformity is reduced, the tendency to re-displacement is greater, and the amount of relief given by reduction less than in dislocation. The use of the Rontgen rays at once establishes the diagnosis.
_Prognosis and Results._--In the majority of cases union takes place satisfactorily by the formation of callus in the spongy tissue of the diaphysis and on the deep surface of the periosteum. In spite of the favourable nature of the prognosis in general, however, the friends of the patient should be warned that a completely satisfactory result cannot always be relied upon.
Deformity, with stiffness and locking at the adjacent joint, especially at the elbow, may result from imperfect reduction, or from exuberant callus. Arrest of growth of the bone in length is a rare sequel, and when it occurs, it is due, not to premature union of the epiphysis with the shaft, but to diminished action at the ossifying junction.
When the growth of one of the bones of the leg or forearm is arrested after separation of its epiphysis while the other bone continues to grow, the foot or hand is deviated towards the side of the shorter one.
Partial separations may be overlooked at the time of the accident and cause trouble later from bending of the bone, as in one variety of c.o.xa vara. The epiphysis at the lower end of the femur may be displaced into the ham and press on the popliteal vessels.
_Treatment._--The general principles which govern the treatment of fractures apply equally to epiphysial separations, the essential being the accurate replacement of the epiphysis.
In _compound separations of epiphysis_, the end of the diaphysis may be pushed through the skin. The entrance of sepsis may prove an obstacle to any operative measure that would otherwise be indicated.
CHAPTER II
INJURIES OF JOINTS
SURGICAL ANATOMY--INJURIES: _Contusions_; _Wounds_; _Sprains_; _Dislocations_--TRAUMATIC DISLOCATIONS: _Causes_: _Varieties_; _Clinical features_; _Treatment_--Compound dislocations--Old-standing dislocations.
#Surgical Anatomy.#--The function of a joint is to permit of the movement of one bone upon another. The articular surfaces are covered with a thin layer of hyaline cartilage, and are retained in apposition by the tension of ligaments and of the muscles surrounding the joint.
The articular capsule (capsular ligament) is directly continuous with the periosteum, and is lined by a synovial layer, which at the line of attachment of the capsule is reflected on to the bone as far as the articular cartilage. The synovial layer invests intra-articular ligaments, and is projected into the interior of the joint in the form of loose folds wherever the articulating surfaces are not in immediate contact. The surface of the synovial layer is covered with minute processes or villi, which in diseased conditions may become hypertrophied. The synovia owes its lubricating property to mucin, derived from the solution of the endothelial cells on the free surface of the synovial layer. The opposing surfaces of a joint being always in accurate contact, the so-called cavity is only a potential one. If fluid is poured out into the joint, the synovial layer and the capsule are put upon the stretch, causing discomfort or actual pain, which is partly relieved by slightly flexing the joint. If the distension persists, the ligaments become elongated and the joint unstable.
The common origin of bone, cartilage, periosteum, and synovial layer from one parent tissue of the embryo, accords with the readiness with which any one of these tissues may be converted into another under traumatic or pathological influences; and how in ligaments and in synovial membrane foci of hyaline cartilage may form and, after increasing in size, undergo ossification.
Joints derive an abundant blood supply through the articular arteries.
The lymphatics, which take origin in the synovial layer, pa.s.s to efferent vessels which run in the intermuscular and other connective-tissue planes of the limb. The nerve supply is derived chiefly from the nerves distributed to the muscles acting on the joint and to the skin over it.
#Sources of Joint Strength.#--The capacity of a joint to resist dislocation depends upon (1) the shape of its osseous elements; (2) the strength and arrangement of its ligaments; (3) the support it receives from muscles or tendons placed in relation to it; and (4) the relative stability of adjacent structures. While all these factors contribute to the strength of a given joint, one or other of them usually predominates, so that certain joints are osseously strong, others are ligamentously strong, while a few depend chiefly upon adjacent muscles for their stability.
The hip and elbows are the best examples of joints deriving their strength mainly from the architectural arrangement of the const.i.tuent bones. These joints are dislocated only by extreme degrees of violence, and not infrequently--especially in the elbow--portions of the bones are fractured before the articular surfaces are separated.
The knee, the wrist, the carpal, the tarsal, and the clavicular joints depend for their stability almost entirely on the strength of their ligaments. These joints are rarely dislocated, but as the main incidence of the violence falls on the ligaments they are frequently sprained.
The shoulder is the typical example of a joint depending for its security chiefly upon the muscles and tendons pa.s.sing over it, and hence the frequency with which it is dislocated when the muscles are taken unawares. At the same time the great mobility of the scapula and clavicle materially increases the stability of the shoulder-joint. The tendons pa.s.sing in relation to the knee, ankle, and wrist add to the stability of these joints.
The proximity of an easily fractured bone also contributes to prevent dislocation of certain joints--for example, fracture of the clavicle prevents an impinging force expending itself on the shoulder-joint; and the frequency of Colles" fracture of the radius, and of Pott"s fracture of the fibula, doubtless accounts to some extent for the rarity of dislocation of the wrist and ankle-joints respectively. The immunity from dislocation which the joints of young subjects enjoy is partly due to the ease with which an adjacent epiphysis is separated.
The mechanical axiom that "what is gained in movement is lost in stability" applies to joints, those which have the widest range of movement being the most frequently dislocated.
The injuries to which a joint is liable are Contusions, Wounds, Sprains, and Dislocations.
#Contusions of Joints.#--Contusion is the mildest form of injury to a joint. Whether the violence is transmitted from a distance, as in contusion of the hip from a fall on the feet, or acts more directly, as in a fall on the great trochanter, the bones are violently driven against one another, and the force expends itself on their articular surfaces. The articular cartilages and the underlying spongy bone, as well as the synovial lining, are bruised, and there is an effusion of blood and serous fluid into the joint and surrounding tissues.
The most prominent _clinical features_ are swelling and discoloration.