Introduction

Tuberculosis (TB) of the spine (Pott’s disease) is the most common site of bone infection in TB; hips and knees are also often affected.  The lower thoracic and upper lumbar vertebrae are the areas of the spine most often affected. 

Pathogenesis Of Pott’s Disease

Pott’s disease results from haematogenous spread of tuberculosis from other sites, often pulmonary.  The infection then spreads from two adjacent vertebrae into the adjoining disc space.  If only one vertebra is affected, the disc is normal, but if two are involved the intervertebral disc, which is avascular, cannot receive nutrients and collapses. The disc tissue dies and is broken down by caseation, leading to vertebral narrowing and eventually to vertebral collapse and spinal damage).  A dry soft tissue mass often forms and superinfection is rare.

Diagnosis of Pott’s disease

Clinical

The disease progresses slowly.  Signs and symptoms include:

• Localised back pain
• Paravertebral swelling may be seen
• Systemic signs and symptoms of TB may be present
• Neurological signs may occur, leading to paraplegia.

Microbiology

• Needle biopsy of bone or synovial tissue. Numbers of tubercle bacilli present are usually low but are pathognomonic. 
• Acid-fast stain and culture for Mycobacterium tuberculosis, plus fungi and other pathogens, should be performed.

Imaging

• Spinal x-ray may not show early disease as 50% of bone mass must be lost for changes to be visible on x-ray. However, plain radiographs can show vertebral destruction and narrowed disc space.
• MRI is useful to demonstrate the extent of spinal compression and can show changes at an earlier stage than plain radiographs. Bone elements visible within the swelling, or abscesses, are strongly indicative of Pott’s disease as opposed to malignancy. 
• CT scans and nuclear bone scans can also be used.

Management of Pott’s disease

Drug treatment is generally sufficient for Pott’s disease, with spinal immobilisation if required.  Surgery is required if there is spinal deformity or neurological signs of spinal cord compression.

Standard antituberculosis treatment is required.

Duration of antituberculosis treatment:

• If debridement and fusion with bone grafting are performed, treatment can be for six months
• If debridement and fusion with bone grafting are NOT performed a minimum of 12 months’ treatment is required.

 

 Pathogenesis of Pott’s disease

Pott’s disease results from haematogenous spread of tuberculosis from other sites, often pulmonary.  The infection then spreads from two adjacent vertebrae into the adjoining disc space.  If only one vertebra is affected, the disc is normal, but if two are involved the intervertebral disc, which is avascular, cannot receive nutrients and collapses. The disc tissue dies and is broken down by caseation, leading to vertebral narrowing and eventually to vertebral collapse and spinal damage).  A dry soft tissue mass often forms and superinfection is rare.

 

Signs and symptoms by site of infection
Pulmonary TB	Fever, productive cough, anorexia, fatigue and night sweats.
Tuberculous meningitis	Headache (intermittent or persistent for 2–3 weeks). Confusion or other subtle changes in mental status. Fever may be low grade or absent. Patient may progress to coma over a few days or weeks.
Skeletal TB (most common is the spine; Potts’ disease)	Pain and stiffness which may lead to paralysis of the lower limbs. Tubercular arthritis is usually a monoarthritis affecting primarily the hip or knee and less commonly the ankle, elbow, wrist and shoulder.

 Pott's disease