More discriminating diagnoses have resulted in a surprising increase in the prevalence of pyogenic osteomyelitis of the spine. The large series observed at the University Hospitals, Iowa City, may be partially accounted for by the rural environment from which most of these patients came, it being generally stated that pyogenic bone infection is most common in such districts. Almost 1 per cent. of all cases hospitalized in these Clinics is due to some form of pyogenic osteomyelitis. There is no evidence to show that pyogenic bone infections in general are gradually diminishing or becoming more benign in this country, as was recently observed by a British writer in his clinic groups.

The diagnosis of pyogenic spondylitis can be made reasonably early if the disease is considered at all. In fact, a knowledge of the disease is the primary factor in the diagnosis. Clinically, there occur acute, subacute, and chronic forms which are not conditional upon the extent of the lesion, but upon the associated bacteriemia and other complications,—particularly the rapidity with which suppuration and abscess formation ensue. The disease is common in adults, although it predominates in the second and most active decade of life. Any part of the vertebral system may be affected, but essentially the disease attacks the bodies of the vertebrae sooner or later, especially if prompt adequate treatment has not been instituted.

The mortality is still too high. It may be axiomatically stated that operative intervention is imperative, as soon as the diagnosis is made with a reasonable degree of certainty, when suppuration is present or suspected in the acute or chronic stages of the disease. The extent of the operation is necessarily limited by the operative risk and the important static function of the spine. The secondary purulent infiltrations must continue to demand our primary surgical considerations. The adequate evacuation and continued drainage of such collections offer great difficulties, and, in general, can best be accomplished by observing Orr's principles. It is an impressive lesson to observe at autopsy the presence of huge pelvic and psoas abscesses after one has thought that the local situation had been adequately taken care of. On the other hand, there are several patients in this series who, following a prolonged period of suffering and discouragement, are well only because of a persistent repeated attack upon the disease. The lumbosacral lesions are particularly difficult to evaluate clinically, especially after one or more of the sacro-iliac joints have become involved by extension (Fig. 10). The primary spinal focus requires the first attention of the surgeon, and any pelvic purulent collection or infiltration should be attacked from every surface possible in order to bring about its successful evacuation and continuous drainage.

No other location reveals so clearly as the spine that we are dealing primarily with a septicaemia in the acute stages of pyogenic osteomyelitis. The local skeletal manifestations of the disease are of secondary importance until suppuration has occurred. Patients who die in the early acute stages do so because of the intense general sepsis. It is fortunate that, in dealing with spinal foci, we need not concern ourselves with the old debate relative to the early attack upon the bony focus in acute pyogenic bone infection. In treating these lesions, the rule of adequate drainage and rest, as soon as the diagnosis is made, should be followed until further knowledge about the relationship between the port of infectious entry, the septicaemia, and the local condition contra-indicates such measures.