In tuberculous spondylitis the lumbar or lower thoracic spine is most often involved.
The disease usually begins in the anterior inferior vertebral body* and spreads beneath the anterior (or posterior) longitudinal ligament to involve adjacent vertebral bodies, and secondarily the intervening disc(s).
Osteonecrosis and wedging of vertebral bodies causes a typical gibbus deformity.
In South Africa, Pott’s disease is the commonest cause of kyphosis in adults. 

Pott's disease diagram
Sagittal section of four lumbar vertebrae and their ligaments.
Image source (adapted from): http://en.wikipedia.org/wiki/File:Gray301.png
 
 

Tuberculous spondylitis

Photograph and X-ray: severe kyphosis ("hunchback") as well as scoliosis and loss of height.

Mr HM, 32 years: In this case the disease is very advanced; complete destruction of a number of vertebrae has resulted in severe kyphosis ("hunchback") as well as scoliosis and loss of height.

 

Photograph: cold abscess

A common complication of tuberculous spondylitis is paravertebral, extradural or other soft tissue cold abscess. This can in turn result in a draining sinus in the lumbar triangle, groin or buttocks. In spinal tuberculosis there is seldom direct involvement of the cord but compression can cause neurologic deficit, typically Pott's paraplaegia. 
(Tuberculosis of the cervical spine is rapidly progressive, and particularly dangerous due to pressure effects. Tuberculosis of the cervical spine is very often associated with retropharyngeal abscess.)