Skeletal Tuberculosis: Pathogenesis and Disease Progression

Skeletal tuberculosis (TB) is a rare but severe form of tuberculosis that affects the bones and joints. It is caused by Mycobacterium tuberculosis and primarily occurs due to hematogenous spread from primary pulmonary infections.

Pathogenesis

The disease begins when Mycobacterium tuberculosis disseminates from a primary site—usually the lungs—to the skeletal system through the bloodstream. The vertebral bodies, particularly the thoracic and lumbar spine, are the most commonly affected regions.

Stages of Disease Progression

• Initial Infection: The bacteria infiltrate bone tissues, leading to granuloma formation.
• Caseation and Necrosis: Immune response leads to tissue necrosis and cavitation.
• Abscess Formation: Cold abscesses may develop due to the liquefactive necrosis of infected tissues.
• Joint Involvement: Tuberculous arthritis affects synovial membranes, causing joint destruction.

Clinical Features

Symptoms of skeletal TB include:

• Persistent bone pain
• Swelling and localized tenderness
• Joint stiffness and deformities
• Neurological deficits in spinal TB cases

Diagnosis

Diagnostic methods include:

• Radiological Imaging: X-rays and MRI scans detect bone destruction.
• Biopsy & Histopathology: Confirms presence of granulomatous inflammation.
• Polymerase Chain Reaction (PCR): Detects M. tuberculosis DNA.

Treatment

The mainstay of skeletal TB management involves:

• Anti-Tubercular Therapy (ATT): A prolonged course of rifampicin, isoniazid, pyrazinamide, and ethambutol.
• Surgical Intervention: Necessary in severe cases with abscess drainage or spinal decompression.
• Physiotherapy: Helps restore joint function and mobility.