OR4.1 | Skeletal Tuberculosis of Major Joints and Spine — Summary & Reflection

KEY TAKEAWAYS

Skeletal tuberculosis is a chronic haematogenous infection caused by Mycobacterium tuberculosis, most commonly affecting the lower thoracic and thoracolumbar spine (Pott's disease), followed by the hip and knee. The pathological hallmark is caseating granuloma leading to cold abscess formation — a fluctuant, non-tender swelling without local heat or erythema. In the spine, anterior vertebral body destruction produces anterior wedging and the characteristic gibbus deformity. The most feared complication is Pott's paraplegia from cord compression, which may be 'active' (abscess/granulation tissue — potentially reversible with ATT or surgery) or 'healed' (bony sequestrum — usually needs surgery). Investigations include ESR/CRP, Mantoux/IGRA, CBNAAT/GeneXpert on aspirated material (rapid and detects RIF resistance), mycobacterial culture (gold standard), and MRI spine (investigation of choice for spinal TB, detects early marrow and cord changes). Standard treatment is ATT: 2HRZE/4HR (6 months). Surgical indications include diagnostic uncertainty, progressive neurological deficit (where anterior debridement and fusion is preferred over posterior laminectomy alone), large symptomatic cold abscess, and spinal instability. Key differentiator from pyogenic infection: the indolent tempo and the cold abscess (no heat, no redness, no tenderness).

REFLECT

Consider the following reflective questions as you conclude this module:

1. Clinical reasoning: You assess a 35-year-old woman with 8 months of low back pain. Her ESR is 110 mm/h and plain X-ray shows disc space narrowing at L1-L2 with a faint paravertebral shadow. Her CBNAAT is negative. Would you still treat for TB, and what additional steps would you take to confirm the diagnosis? How does the prevalence of TB in India influence your prior probability?

1. Systems thinking: Skeletal TB is often a sign of an underlying systemic TB burden. Should a patient with newly diagnosed Pott's disease be screened for pulmonary or other forms of extrapulmonary TB? What resources are needed in the primary care setting to achieve this?

1. Patient counselling: You need to explain to a young patient that they require 6 months of four-drug therapy with a risk of hepatotoxicity and that surgery may be needed if neurology worsens. How would you communicate this in a way that supports adherence while avoiding excessive anxiety? What would you tell a patient who wants to stop treatment after 2 months because they feel better?