A fracture may be rendered compound from without, the soft parts being damaged by the object which breaks the bone—as, for example, a cart wheel, a piece of machinery, or a bullet. Sloughing of soft parts resulting from the pressure of improperly applied splints, also, may convert a simple into a compound fracture. On the other hand, a simple fracture may be rendered compound from within—for example, a sharp fragment of bone may penetrate the skin; this is the least serious variety of compound fracture.
As a rule, it is easy to recognise that the fracture is compound, as the bone can either be seen or felt.
The prognosis depends on the success which attends the efforts to make and to keep the wound aseptic, as well as on the extent of damage to the tissues. When asepsis is secured, repair takes place as in simple fracture, only it usually takes a little longer; sometimes the reason for the delay is obvious, as when the compound fracture is the result of a more severe form of violence and where there is comminution and loss of one or more portions of bone that would have contributed to the repair. Sometimes the delay cannot be so explained; Bier suggested that it is due to the escape of blood at the wound, whereas in simple fractures the blood is retained and assists in repair.
If sepsis gains the upper hand in a compound fracture there is, firstly, the risk of infection of the marrow—osteomyelitis—which in former times was liable to result in pyæmia; in the second place, not only do loose fragments tend to die and be thrown off as sequestra, but the ends of the fragments themselves may undergo necrosis; involving as this does the dense cortical bone of the shaft, the dead bone is slow in being separated, and until it is separated and thrown off, no actual repair can take place. The sepsis stimulates the bone-forming tissues and new bone is formed in considerable amount, especially on the surface of the shaft in the vicinity of the fracture; in macerated specimens it presents a porous, crumbling texture. Sometimes the new bone—which corresponds to the involucrum of an osteomyelitis—imprisons a sequestrum and prevents its extrusion, in which case one or more sinuses may persist indefinitely. Cases are met with where such sinuses have existed for the best part of a long life and have ultimately become the seat of epithelioma.
It should be noted that all the above changes can be followed in skiagrams.
Treatment.—The leading indication is to ensure asepsis. Even in the case of a small punctured wound caused by a pointed fragment coming through the skin it is never wise to assume that the wound is not infected. It is much safer to enlarge such a wound, pare away the bruised edges, and disinfect the raw surfaces.
In cases of extensive laceration of the soft parts, all soiled, bruised, or torn portions of tissue should be clipped away with scissors, blood-clots removed, and the bleeding arrested by forci-pressure or ligature. If there is any reason to believe that the wound is infected, any fragments of bone completely separated from the periosteum should be removed. In comminuted fractures, extension applied by strips of plaster or by means of ice-tong callipers or Steinmann's apparatus ([p. 150]) often facilitates replacement of the fragments and their retention in position. Plates and screws are not recommended for comminuted fractures, owing to the mechanical difficulty of fixing a number of small fragments and the risks of infection. The wound should be purified with eusol, and the surrounding parts painted with iodine. On the whole, it is safer not to attempt to obtain primary union by completely closing such wounds, but rather to drain or pack them. To increase the local leucocytosis and so check the spread of infection, a Bier's constricting bandage may be applied.
In other respects the treatment is carried out on the same lines as in simple fractures, provision being made for dressing the wound without disturbance of the fracture. Massage and movement should be commenced after the wound is healed and the condition has become analogous to a simple fracture.
Question of Amputation in Compound Fractures.—Before deciding to perform primary amputation of a limb for compound fracture, the surgeon must satisfy himself (1) that the attainment of asepsis is impossible; (2) that the soft parts are so widely and so grossly damaged that their recovery is improbable; (3) that the vascular and nervous supply of the parts beyond has been rendered insufficient by destruction of the main blood vessels and nerve-trunks; (4) that the bones have been so shattered as to be beyond repair; and (5) that the limb, even if healing takes place, will be less useful than an artificial one.
In attempting to save the limb of a young subject, it is justifiable to run risks which would not be permissible in the case of an older person. To save an upper limb, also, risks may be run which would not be justifiable in the case of a lower limb, because, while a serviceable artificial leg can readily be procured, any portion of the natural hand or arm is infinitely more useful than the best substitute which the instrument-maker can contrive. The risk involved in attempting to save a limb should always be explained to the patient or his guardian, in order that he may share the responsibility in case of failure.