OR4.1 | Skeletal Tuberculosis — Glossary

A bacterium that, due to its high mycolic acid content, retains the carbol-fuchsin stain even after treatment with acid-alcohol in the Ziehl-Neelsen technique; Mycobacterium tuberculosis is the principal pathogenic acid-fast bacillus encountered in clinical practice.

The preferred surgical approach for Pott's paraplegia due to anterior cord compression, involving removal of infected anterior vertebral tissue and epidural abscess, decompression of the spinal canal, and stabilisation with a strut graft and instrumented fusion.

Reduction in anterior vertebral body height relative to the posterior height due to destruction of the anterior vertebral cortex and trabecular bone in Pott's disease, producing progressive kyphosis.

The pharmacological regimen used to treat tuberculosis; for drug-sensitive TB the standard regimen is 2 months of isoniazid + rifampicin + pyrazinamide + ethambutol (2HRZE) followed by 4 months of isoniazid + rifampicin (4HR), totalling 6 months.

The histopathological hallmark of tuberculosis — a collection of epithelioid macrophages, Langhans' giant cells, and lymphocytes surrounding a central zone of caseous (cheese-like) necrosis, representing the host's failed containment of the mycobacterium.

A form of coagulative necrosis in which the dead tissue has a soft, cheese-like (caseous) consistency; the central finding in tuberculous granulomas and the precursor to cold abscess formation when it liquefies.

Cartridge-Based Nucleic Acid Amplification Test that detects Mycobacterium tuberculosis DNA and rifampicin resistance in a sample within 2 hours; the preferred rapid diagnostic test in the National TB Elimination Programme (NTEP) of India.

A fluctuant collection of liquefied caseous pus formed in chronic granulomatous infections (primarily TB), characterised by the absence of local heat, redness, and tenderness because there is no acute suppurative reaction.

A non-specific marker of systemic inflammation reflecting the rate at which red cells settle in anticoagulated plasma; elevated in active TB (often 60–120 mm/h in skeletal TB) and useful for monitoring treatment response, though normalisation may take 6–12 months.

A sharply angular kyphotic deformity of the spine resulting from anterior collapse of one or more vertebral bodies in Pott's disease, producing a visible and palpable bony prominence over the affected level.

A blood-based immunological test (e.g. QuantiFERON-TB Gold) that measures interferon-gamma release by sensitised T lymphocytes in response to M. tuberculosis-specific antigens; more specific than the Mantoux test in BCG-vaccinated individuals.

A bactericidal first-line anti-tuberculosis drug that inhibits mycolic acid synthesis; major adverse effects are hepatotoxicity and peripheral neuropathy (prevented by pyridoxine supplementation in high-risk patients).

A multinucleate giant cell formed by fusion of macrophages/monocytes, characteristically arranged in a horseshoe or ring pattern with peripheral nuclei; found in the granulomas of tuberculosis and distinguishable from the foreign-body giant cell in which nuclei are randomly arranged centrally.

The tuberculin skin test in which 5 TU (0.1 mL) of purified protein derivative (PPD) is injected intradermally and induration read at 48–72 hours; ≥10 mm induration is positive in immunocompetent individuals in high-burden settings; a positive result indicates TB exposure/infection, not necessarily active disease.

Tuberculosis of the spine, typically affecting the lower thoracic and thoracolumbar junction, resulting from haematogenous seeding of the anterior vertebral body with subsequent disc destruction, vertebral wedging, and potential cord compression.

Paralysis or paresis of the lower limbs resulting from spinal cord or cauda equina compression in patients with spinal TB; classified as 'active' (due to epidural abscess or granulation tissue — potentially reversible) or 'healed' (due to bony sequestrum — usually requires surgery).

A cold abscess arising from lumbar spinal TB that tracks along the fascial sheath of the psoas major muscle, presenting as a fluctuant, non-tender swelling in the iliac fossa, inguinal region, or upper thigh.

A bactericidal first-line anti-tuberculosis drug that inhibits RNA polymerase; a potent inducer of cytochrome P450 enzymes causing multiple drug interactions; causes orange-red discolouration of urine and secretions; hepatotoxic.

A chronic narrow channel connecting a deep focus of infection (abscess, sequestrum) to the skin surface, formed when a cold abscess discharges spontaneously or is inadequately drained; in skeletal TB, secondary bacterial colonisation of the sinus is common.

Infection of bones and joints by Mycobacterium tuberculosis, spread haematogenously from a primary pulmonary or lymph node focus; characterised by indolent onset, granulomatous pathology, and cold abscess formation.

Inflammation of the synovial membrane lining a joint; in joint TB this represents the earliest stage (Stage 1 of Girdlestone's classification), manifesting as synovial thickening, effusion, and a doughy consistency on palpation, before cartilage and bone are destroyed.

An orthopaedic traction splint used in femoral shaft fractures and also for immobilisation of the hip or lower limb in conditions such as hip TB in children; applies traction and controls hip and knee position.