Tuberculosis of the spine also known as Koch's spine and Tuberculous Vertebral Osteomyelitis is the commonest form of
skeletal tuberculosis and accounts for 88% of chronic vertebral infections. 30% of Kochs spine occur before the age of 10 years.
Incidence of Koch's spineThere are 30 million cases of tuberculosis in the world. 6 million cases of sputum positive tuberculosis are in India. 1-3% cases have skeletal tuberculosis.
PathophysiologyVertebral affection occurs due to hematogenous dissemination from a primary infected organ (usually pulmonary or lymph node). The primary focus may be active or quiescent, apparent or latent.
Simultaneous involvement of paradiscal parts of two contiguous vertebrae is the typical lesion. This is due to a common blood supply of adjacent vertebrae. The other type of affections are central type, anterior and posterior type.
Histopathological picture of spinal TB
Pathologically, tuberculosis occurs in two forms:
- The granulomatous inflammation characterized by granulation tissue and tubercles.
- Caseous type associated with abscess and sinus formation.
Following infection, there is marked hyperemia and osteoporosis. Osseous destruction takes place by lysis of bone, which is thus softened and easily yields under effects of gravity and muscle action, leading to compression, collapse and deformation of bone. Necrosis also takes place due to ischemic infarction of segments of bone. This change is secondary to arterial occlusion due to thrombo-embolic phenomenon, endarteritis and peri- arteritis.
The intervertebral disc is not involved primarily because of its avascularity. Damage to the vertebral end plates and adjacent articular cartilage results in loss of its nutrition. The disc gets degenerated and may become separated as a sequestrum.