In typhoid fever the bone marrow is liable to be invaded by the typhoid bacillus, which may set up osteomyelitis soon after its lodgment, or it may lie latent for a considerable period before doing so. The lesions may be single or multiple, they involve the marrow or the periosteum or both, and they may or may not be attended with suppuration. They are most commonly met with in the tibia and in the ribs at the costo-chondral junctions.
The bone lesions usually occur during the seventh or eighth week of the fever, but have been known to occur much later. The chief complaint is of vague pains, at first referred to several bones, later becoming localised in one; they are aggravated by movement, or by handling the bone, and are worst at night. There is redness and œdema of the overlying soft parts, and swelling with vague fluctuation, and on incision there escapes a yellow creamy pus, or a brown syrupy fluid containing the typhoid bacillus in pure culture. Necrosis is exceptional.
When the abscess develops slowly, the condition resembles tuberculous disease, from which it may be diagnosed by the history of typhoid fever, and by obtaining a positive Widal reaction.
The prognosis is favourable, but recovery is apt to be slow, and relapse is not uncommon.
It is usually sufficient to incise the periosteum, but when the disease occurs in a rib it may be necessary to resect a portion of bone.
Pyogenic Osteomyelitis due to Spread of Infection from the Soft Parts.—There still remain those forms of osteomyelitis which result from infection through a wound involving the bone—for example, compound fractures, gun-shot injuries, osteotomies, amputations, resections, or operations for un-united fracture. In all of these the marrow is exposed to infection by such organisms as are present in the wound. A similar form of osteomyelitis may occur apart from a wound—for example, infection may spread to the jaws from lesions of the mouth; to the skull, from lesions of the scalp or of the cranial bones themselves—such as a syphilitic gumma or a sarcoma which has fungated externally; or to the petrous temporal, from suppuration in the middle ear.
Fig. 122.—Tubular Sequestrum resulting from Septic Osteomyelitis in Amputation Stump.
The most common is an osteomyelitis commencing in the marrow exposed in a wound infected with pyogenic organisms. In amputation stumps, fungating granulations protrude from the sawn end of the bone, and if necrosis takes place, the sequestrum is annular, affecting the cross-section of the bone at the saw-line; or tubular, extending up the shaft, and tapering off above. The periosteum is more easily detached, is thicker than normal, and is actively engaged in forming bone. In the macerated specimen, the new bone presents a characteristic coral-like appearance, and may be perforated by cloacæ ([Fig. 122]).