The synovial type plays a minor role compared with the osteal one and is only observed in the uppermost joints of the spine.
Lexer, through his studies of the normal blood-supply in the ver tebra of the young, has taught us the mode of the tubercular infection of the vertebrx. There are three principal distributions of the blood vessels in the body of the vertebra. One pair enters the body from behind from the arterize spinales and forms many branches and anus tomoses; two small arteries come from the periphery to the anterior surface of the body, and a third pair enters at the base of the trans verse process.
The branches of the blood-vessels are especially numerous at the epiphyseal zone of the bodies of the vertebra, and here we will most frequently observe the deposit of the tubercular embolus and the typical cuneiform focus.
The spread of the tuberculosis follows the typical course of the blood-vessels and offers nothing of special interest. It is usually the granulation type, either spreading from one centre all over the body of the vertebra or several foci in the epiphyses run together. Here also we find caseation, and occasionally suppuration. The process breaks through the intervertebral cartilages and attacks the next vertebrae, either through contiguity or through infection by means of the blood and lymph stream.
After one or more bodies of vertebra have been destroyed, the weight of the body will bend the spine in such a manner that the healthy ver tebra come near together and the intact portion of the affected ones is pushed backwards. In this position fibrous or more rarely bony union may set in (formation of gibbus).
Naturally, in cavities in the bones, sequestra may develop and pus may be formed which will appear at some distance from its origin as a gravitation abscess. (See Abscesses.) The most obvious change is the deformity of the spine. The granu lating as well as the necrotic and the purulent type destroy the vertebra', bend the spine, and force the spinous processes and the bodies of the diseased backwards into the kyphotic protuberance. This is in the beginning button-shaped and pointed (angular type) (Fig. 133a).
When the disease includes several vertebra the protrusion will be more curved (arcuate type) (Fig. 133b). Thus we will see that the shape changes with the number of vertebra affected. The arcuate type indi cates a longer duration of the disease.
Should the disease be located more in the side of the body of the tebra we will find the kyphosis combined with a. corresponding scoliosis. These primary deformities are followed by secondary compensatory ones, which will reverse the natural curve of the spine. A kyphosis in the lumbar spine will be followed by a lordosis in the dorsal region; like wise a kyphosis of the cervical spine will make the natural kyphosis of the dorsal spine disappear. Should, however, the kyphosis be located in a part of the spine which is naturally kyphotie, then the physiological curvature of the spine will be increased (dorsal spine) (Fig. 133b).
All the bony structures connected with the spine have to adapt themselves to these deformities. In kyphosis of the dorsal spine the thorax will be shortened and will appear telescoped from above down ward, but its depth is increased (pectus earinatum). The carriage of the head is usually typical, and appears as if pushed forward and is sunk in between the shoulders owing to the changed position of the cervical vertebrae (Witzel).
All other organs must naturally follow the changes in shape of the spine and the thorax (Wu]'stein).
As mentioned, tuberculous affection of the joints is of importance only when it affects the uppermost joint in the cervical spine, but this affection is much rarer in chihlren than in adults. The synovial tubercles in this region will soon spread to the osseous part of the joint and will there run its typical course.
Nervous Symptoms.—When once the granulations have reached the cortex of the bone, they may protrude towards the inside of the spinal canal, and thus cause a pachymeningitis externa; the du•a is not yet changed, hut soon it will become oedematous, thickened, and attacked by the disease.