Manual of Surgery.
Volume Second.
by Alexander Miles and Alexis Thomson.
CHAPTER I
INJURIES OF BONES
Contusions--Wounds--FRACTURES: _Pathological_; _Traumatic_; _Varieties_--Simple fractures--Compound fractures--Repair of fractures--Interference with repair--Gun-shot fractures--SEPARATION OF EPIPHYSES.
The injuries to which a bone is liable are Contusions, Open Wounds, and Fractures.
#Contusions of Bone# are almost of necessity a.s.sociated with a similar injury of the overlying soft parts. The mildest degree consists in a bruising of the periosteum, which is raised from the bone by an effusion of blood, const.i.tuting a _haematoma of the periosteum_. This may be absorbed, or it may give place to a persistent thickening of the bone--_traumatic node_.
#Open Wounds of Bone# of the incised and contused varieties are usually produced by sabres, axes, butcher"s knives, scythes, or circular saws. Punctured wounds are caused by bayonets, arrows, or other pointed instruments. They are all equivalent to compound, incomplete fractures.
FRACTURES
A fracture may be defined as a sudden solution in the continuity of a bone.
PATHOLOGICAL FRACTURES
A pathological fracture has as its primary cause some diseased state of the bone, which permits of its giving way on the application of a force which would be insufficient to break a healthy bone. It cannot be too strongly emphasised that when a bone is found to have been broken by a slight degree of violence, the presence of some pathological condition should be suspected, and a careful examination made with the X-rays and by other means, before arriving at a conclusion as to the cause of the fracture. Many cases are on record in which such an accident has first drawn attention to the presence of a new-growth, or other serious lesion in the bone. The following conditions, which are more fully described with diseases of bone, may be mentioned as the causes of pathological fractures.
_Atrophy_ of bone may proceed to such an extent in old people, or in those who for long periods have been bed-ridden, that slight violence suffices to determine a fracture. This most frequently occurs in the neck of the femur in old women, the mere catching of the foot in the bedclothes while the patient is turning in bed being sometimes sufficient to cause the bone to give way. Atrophy from the pressure of an aneurysm or of a simple tumour may erode the whole thickness of a bone, or may thin it out to such an extent that slight force is sufficient to break it. In general paralysis, and in the advanced stages of locomotor ataxia and other chronic diseases of the nervous system, an atrophy of all the bones sometimes takes place, and may proceed so far that multiple fractures are induced by comparatively slight causes. They occur most frequently in the ribs or long bones of the limbs, are not attended with pain, and usually unite satisfactorily, although with an excessive amount of callus.
Attendants and nurses, especially in asylums, must be warned against using force in handling such patients, as otherwise they may be unfairly blamed for causing these fractures.
Among diseases which affect the skeleton as a whole and render the bones abnormally fragile, the most important are rickets, osteomalacia, and fibrous osteomyelitis. In these conditions multiple pathological fractures may occur, and they are p.r.o.ne to heal with considerable deformity. In osteomalacia, the bones are profoundly altered, but they are more liable to bend than to break; in rickets the liability is towards greenstick fractures.
Of the diseases affecting individual bones and predisposing them to fracture may be mentioned suppurative osteomyelitis, hydatid cysts, tuberculosis, syphilitic gummata, and various forms of new-growth, particularly sarcoma and secondary cancer. It is not unusual for the sudden breaking of the bone to be the first intimation of the presence of a new-growth. In adolescents, fibrous osteomyelitis affecting a single bone, and in adults, secondary cancer, are the commonest local causes of pathological fracture.
_Intra-uterine fractures_ and fractures occurring _during birth_ are usually a.s.sociated with some form of violence, but in the majority of cases the ftus is the subject of const.i.tutional disease which renders the bones unduly fragile.
TRAUMATIC FRACTURES
Traumatic fractures are usually the result of a severe force acting from without, although sometimes they are produced by muscular contraction.
When the bone gives way at the point of impact of the force, the violence is said to be _direct_, and a "fracture by compression"
results, the line of fracture being as a rule transverse. The soft parts overlying the fracture are more or less damaged according to the weight and shape of the impinging body. Fracture of both bones of the leg from the pa.s.sage of a wheel over the limb, fracture of the shaft of the ulna in warding off a stroke aimed at the head, and fracture of a rib from a kick, are ill.u.s.trative examples of fractures by direct violence.
When the force is transmitted to the seat of fracture from a distance, the violence is said to be _indirect_, and the bone is broken by "torsion" or by "bending." In such cases the bone gives way at its weakest point, and the line of fracture tends to be oblique. Thus both bones of the leg are frequently broken by a person jumping from a height and landing on the feet, the tibia breaking in its lower third, and the fibula at a higher level. Fracture of the clavicle in its middle third, or of the radius at its lower end, from a fall on the outstretched hand, are common accidents produced by indirect violence.
The ribs also may be broken by indirect violence, as when the chest is crushed antero-posteriorly and the bones give way near their angles.
In fractures by indirect violence the soft parts do not suffer by the violence causing the fracture, but they may be injured by displacement of the fragments.
In fractures by _muscular action_ the bone is broken by "traction" or "tearing." The sudden and violent contraction of a muscle may tear off an epiphysis, such as the head of the fibula, the anterior superior iliac spine, or the coronoid process of the ulna; or a bony process may be separated, as, for example, the tuberosity of the calcaneus, the coracoid process of the scapula, or the larger tubercle (great tuberosity) of the humerus. Long bones also may be broken by muscular action. The clavicle has snapped across during the act of swinging a stick, the humerus in throwing a stone, and the femur when a kick has missed its object. Fractures of ribs have occurred during fits of coughing and in the violent efforts of parturition.
Before concluding that a given fracture is the result of muscular action, it is necessary to exclude the presence of any of the diseased conditions that lead to pathological fracture.
Although the force acting upon the bone is the primary factor in the production of fractures, there are certain subsidiary factors to be considered. Thus the age of the patient is of importance. During infancy and early childhood, fractures are less common than at any other period of life, and are usually transverse, incomplete, and of the nature of bends. During adult life, especially between the ages of thirty and forty, the frequency of fractures reaches its maximum. In aged persons, although the bones become more brittle by the marrow s.p.a.ces in their interior becoming larger and filled with fat, fractures are less frequent, doubtless because the old are less exposed to such violence as is likely to produce fracture.
Males, from the nature of their occupations and recreations, sustain fractures more frequently than do females; in old age, however, fractures are more common in women than in men, partly because their bones are more liable to be the seat of fatty atrophy from senility and disease, and partly because of their clothing--a long skirt--they are more exposed to unexpected or sudden falls.
[Ill.u.s.tration: FIG. 1.--Multiple Fracture of both Bones of Leg.]
#Clinical Varieties of Fractures.#--The most important subdivision of fractures is that into simple and compound.
In a _simple_ or subcutaneous fracture there is no communication, directly or indirectly, between the broken ends of the bone and the surface of the skin. In a _compound_ or open fracture, on the other hand, such a communication exists, and, by furnishing a means of entrance for bacteria, may add materially to the gravity of the injury.
A simple fracture may be complicated by the existence of a wound of the soft parts, which, however, does not communicate with the broken bone.
Fractures, whether simple or compound, fall into other clinical groups, according to (1) the degree of damage done to the bone, (2) the direction of the break, and (3) the relative position of the fragments.
(1) _According to the Degree of Damage done to the Bone._--A fracture may be incomplete, for example in _greenstick fractures_, which occur only in young persons--usually below the age of twelve--while the bones are still soft and flexible. They result from forcible bending of the bone, the osseous tissue on the convexity of the curve giving way, while that on the concavity is compressed. The clavicle and the bones of the forearm are those most frequently the seat of greenstick fracture (Fig. 41). _Fissures_ occur on the flat bones of the skull, the pelvic bones, and the scapula; or in a.s.sociation with other fractures in long bones, when they often run into joint surfaces.
_Depressions_ or indentations are most common in the bones of the skull.
The bone at the seat of fracture may be broken into several pieces, const.i.tuting a _comminuted_ fracture. This usually results from severe degrees of direct violence, such as are sustained in railway or machinery accidents, and in gun-shot injuries (Fig. 2).
[Ill.u.s.tration: FIG. 2.--Radiogram of Comminuted Fracture of both Bones of Forearm.]
_Sub-periosteal_ fractures are those in which, although the bone is completely broken across, the periosteum remains intact. These are common in children, and as the thick periosteum prevents displacement, the existence of a fracture may be overlooked, even in such a large bone as the femur.
A bone may be broken at several places, const.i.tuting a _multiple_ fracture (Fig. 1).
_Separation of bony processes_, such as the coracoid process, the epicondyle of the humerus, or the tuberosity of the calcaneus, may result from muscular action or from direct violence. _Separation of epiphyses_ will be considered later.
(2) _According to the Direction of the Break._--_Transverse_ fractures are those in which the bone gives way more or less exactly at right angles to its long axis. These usually result from direct violence or from end-to-end pressure. _Longitudinal_ fractures extending the greater part of the length of a long bone are exceedingly rare.
_Oblique_ fractures are common, and result usually from indirect violence, bending, or torsion (Fig. 3). _Spiral_ fractures result from forcible torsion of a long bone, and are met with most frequently in the tibia, femur, and humerus.
[Ill.u.s.tration: FIG. 3.--Showing (1) Oblique fracture of Tibia; (2) Oblique fracture with partial separation of Epiphysis of upper end of Fibula; (3) Incomplete fracture of Fibula in upper third. Result of railway accident. Boy aet. 16.]
(3) _According to the Relative Position of the Fragments._--The bone may be completely broken across, yet its ends remain in apposition, in which case there is said to be _no displacement_. There may be an _angular_ displacement--for example, in greenstick fracture. In transverse fractures of the patella or of the olecranon there is often _distraction_ or pulling apart of the fragments (Fig. 35). The broken ends, especially in oblique fractures, may _override_ one another, and so give rise to shortening of the limb (Fig. 2). Where one fragment is acted upon by powerful muscles, a _rotatory_ displacement may take place, as in fracture of the radius above the insertion of the p.r.o.nator teres, or of the femur just below the small trochanter. The fragments may be _depressed_, as in the flat bones of the skull or the nasal bones. At the cancellated ends of the long bones, particularly the upper end of the femur and humerus, and the lower end of the radius, it is not uncommon for one fragment to be _impacted_ or wedged into the substance of the other (Fig. 28).
_Causes of Displacement._--The factors which influence displacement are chiefly mechanical in their action. Thus the direction and nature of the fracture play an important part. Transverse fractures with roughly serrated ends are less liable to displacement than those which are oblique with smooth surfaces. The direction of the causative force also is a dominant factor in determining the direction in which one or both of the fragments will be displaced. Gravity, acting chiefly upon the distal fragment, also plays a part in determining the displacement--for example, in fractures of the thigh or of the leg, where the lower segment of the limb rolls outwards, and in fractures of the shaft of the clavicle, where the weight of the arm carries the shoulder downwards, forwards, and medially. After the break has taken place and the force has ceased to act, displacement may be produced by rough handling on the part of those who render first aid, the careless or improper application of splints or bandages, or by the weight of the bedclothes.
In certain situations the contraction of unopposed, or of unequally opposed, groups of muscles plays a part in determining displacement.
For example, in fracture immediately below the lesser trochanter of the femur, the ilio-psoas tends to tilt the upper fragment forward and laterally; in supra-condylar fracture of the femur, the muscles of the calf pull the lower fragment back towards the popliteal s.p.a.ce; and in fracture of the humerus above the deltoid insertion, the muscles inserted into the inter-tubercular (bicipital) groove adduct the upper fragment.
REPAIR OF INJURIES OF BONE
In a _simple fracture_ the vessels of the periosteum and the marrow being torn at the same time as the bone is broken, blood is poured out, and clots around and between the fragments. This clot is soon permeated by newly formed blood vessels, and by leucocytes and fibroblasts, the latter being derived from proliferation of the cells of the marrow and periosteum. The granulation tissue thus formed resembles in every particular that described in the repair of other tissues, except that the fibroblasts, being the offspring of cells which normally form bone, a.s.sume the functions of _osteoblasts_, and proceed to the formation of bone. The new bone may be formed either by a direct conversion of the fibrous tissue into osseous tissue, the osteoblasts arranging themselves concentrically in the recesses of the capillary loops, and secreting a h.o.m.ogeneous matrix in which lime salts are speedily deposited; or there may be an intermediate stage of cartilage formation, especially in young subjects, and in cases where the fragments are incompletely immobilised. The newly formed bone is at first arranged in little ma.s.ses or in the form of rods which unite with each other to form a network of spongy bone, the meshes of which contain marrow.
The reparative material, consisting of granulation tissue in the process of conversion into bone, is called _callus_, on account of its hard and unyielding character. In a fracture of a long bone, that which surrounds the fragments is called the _external_ or _ensheathing callus_, and may be likened to the ma.s.s of solder which surrounds the junction of pipes in plumber-work; that which occupies the position of the medullary ca.n.a.l is called the _internal_ or _medullary callus_; and that which intervenes between the fragments and maintains the continuity of the cortical compact tissue of the shaft is called the _intermediate callus_. This intermediate callus is the only permanent portion of the reparative material, the external and internal callus being only temporary, and being largely re-absorbed through the agency of giant cells.