The general symptoms are common to the disease, no matter what bone be involved. Local symptoms will change in accordance with their location. While not so common, the flat bones, like the pelvis, cranium, and sternum, may be involved in active manifestations of this disease. The same is true even of the vertebræ, but, as a rule, it is in the long bones of the extremities that its ravages are most frequently seen.
Prognosis.
—The prognosis depends upon the early recognition of the disease and prompt surgical relief. There is perhaps no disease less amenable to purely medicinal treatment, and if bones are to be saved in their entirety early and free incision is called for. Consequently when the case is seen late it almost invariably entails necrosis, with more or less disturbance of function, or possibly such a serious condition as to call for amputation. The fulminant cases when not early recognized and promptly operated often prove fatal, and death has been known to follow within thirty-six hours after the onset of the first symptom, the fatal result being due to overwhelming septic infection, with thrombosis, etc. Almost every case, however, if seen sufficiently early can be saved.
Complications.
—The complications are to be divided into the constitutional and the local. The former refer rather to the spread of septic infection and its more or less disastrous and remote ravages. Metastatic infections may produce serious or fatal complications, while, when less acute, important functions may suffer a serious impairment. Among the local sequels are to be considered mainly the results of destruction of bone tissue and neighboring joint structures. When the disease occurs in young and rapidly growing children partial or complete arrest of development in the bone involved is not infrequent. This may lead to inequalities in length of the femora or humeri. It may lead also to compensatory hypertrophy of bone, with perhaps considerable distortion during subsequent growth.
An entirely distinct consequence of osteomyelitis is bone abscess, in which the acuteness of symptoms has long since subsided, but in which a distinct local focus remains.
Etiology.
—The disease is an infection from the beginning, but the source of the infection is not always easy to trace. Two distinct causes seem to conspire to produce the majority of these bone infections—microörganisms of more than ordinary virulence, and a predisposing condition of the system, due sometimes to constitutional weakness or inherited taint, or to the results of exposure and fatigue. The causes of suppuration have been discussed in Chapter III. It is a fact, however, that the majority of cases occur in children and after a combination of exposure and fatigue—as, for instance, sitting upon the ice after being exhausted by skating—all of which would be inoperative to produce an infection were not the germs at hand ready to assail every tissue whose resistance is thus temporarily lowered.
The infection may occur from within or from without—from within perhaps through the alimentary canal or the respiratory tract, probably from the tonsils and the pharynx. Infection from without may occur through an abrasion or scratch, a blister upon the foot made by an ill-fitting shoe or by a skate-strap. These cases occur generally in the young, more often in boys than in girls, probably because in the former more opportunities for infection are permitted. Bone infections, however, are possible even in the newborn, in which case the infection may occur through the pharynx or through the umbilicus, while the local resistance may have been lowered by the injury due to mechanical delivery, turning, etc. In elderly people the disease is almost unknown.