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OR4.1 | Skeletal Tuberculosis — Graded Quiz
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A 38-year-old male presents with 9 months of progressive lower back pain radiating to both thighs, mild fever, and night sweats. He has recently developed weakness in both legs (grade 4/5) and hesitancy of micturition. MRI shows destruction of T10–T11 with a large anterior extradural collection and cord compression at T10. CBNAAT of biopsy tissue is positive for M. tuberculosis. After initiating ATT, what is the most appropriate next step in management?
Correct. Significant cord compression with sphincter involvement warrants anterior decompression. The Hong Kong operation (anterior debridement, fusion, and stabilisation) directly addresses the anterior compressing lesion — the standard for Pott's paraplegia not rapidly improving on ATT.
Pott's paraplegia with significant cord compression and incomplete neurological deficit that is not rapidly improving on ATT requires anterior surgical decompression (Hong Kong operation). Posterior laminectomy is contraindicated. Sphincteric involvement signals cord compromise requiring urgent intervention.
Sphincteric dysfunction and significant cord compression are indications for anterior surgical decompression, not conservative ATT alone or posterior laminectomy (which is contraindicated).
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A 12-year-old girl presents with right hip pain, limp, and mild fever for 7 months. On examination there is a fixed flexion-abduction deformity of the right hip. ESR is 68 mm/hr. X-ray shows periarticular osteoporosis and a small marginal erosion of the femoral head. MRI confirms synovial thickening and early cartilage loss. Which of the following is the MOST important radiological feature that helps distinguish early TB hip from pyogenic septic arthritis?
Correct. Phemister's triad — juxta-articular osteoporosis, marginal peripheral erosions, and gradual slow joint space narrowing — is the hallmark of TB joint disease, contrasting with the rapid joint destruction of pyogenic arthritis.
In early TB hip, the joint space is relatively preserved (Phemister's triad: periarticular osteoporosis, marginal erosions, gradual slow joint space loss). In pyogenic arthritis, joint space is rapidly and completely destroyed within days. This temporal and radiological pattern distinguishes the two.
TB joints show Phemister's triad: periarticular osteoporosis, marginal erosions, and slow gradual joint space narrowing — directly contrasting with the rapid catastrophic joint destruction of pyogenic arthritis.
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A 55-year-old male with treated pulmonary TB 10 years ago develops progressive spastic paraplegia. MRI shows healed Pott's disease with bony fusion at L1–L2 but a bony bar and fibrosis causing cord compression. No active caseous material is seen. What type of Pott's paraplegia does this represent and what is the implication for surgery?
Correct. This is paraplegia of the healed phase — caused by a bony bar or fibrosis compressing the cord in the absence of active TB. Results from anterior decompression are less predictable compared to active-phase paraplegia, and prognosis for recovery is worse.
Paraplegia of the healed phase (late-onset Pott's paraplegia) is caused by mechanical compression from a bony ridge, fibrosis, or sequestrum in the absence of active disease. Prognosis is worse than active-phase paraplegia. Surgical decompression (anterior) may improve function but results are less predictable than in active disease.
Late-onset Pott's paraplegia after healed disease is due to mechanical bony/fibrous compression, not active TB. Restarting ATT is unhelpful. Surgical decompression (anterior) may help but prognosis is guarded.
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A 7-year-old girl presents with knee pain, soft tissue swelling around the knee, low-grade fever for 6 months, and minimal joint movement. ESR is 85 mm/hr. Her father has pulmonary TB. Mantoux test: 20 mm induration. Synovial biopsy shows caseating granulomas with Langhans giant cells. Which sign on X-ray, observed in TB knee, indicates subchondral bone involvement?
Correct. Kissing sequestra (mirror-image subchondral erosions on opposing surfaces) are a characteristic radiological finding in TB arthritis, particularly the knee. They indicate bilateral subchondral involvement.
Kissing sequestra (or 'kissing lesions') in TB knee refer to mirror-image subchondral erosions on opposing bone surfaces (e.g., femoral condyle and tibial plateau) — a pathognomonic feature of TB arthritis when present. Additionally, 'wandering acetabulum' describes femoral head migration in TB hip.
Kissing sequestra are the characteristic TB joint finding: mirror-image subchondral erosions on both articular surfaces. Codman's triangle and sunburst/onion-peel periosteal reactions are features of bone tumours.
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A 30-year-old male has TB of the left hip with a cold abscess pointing in the thigh. He is currently on ATT for 4 weeks. What is the appropriate management of the cold abscess?
Correct. Cold abscesses in TB are managed with ATT. If large or causing pressure symptoms, they may be aspirated under aseptic conditions. Open incision is CONTRAINDICATED — it results in a chronic discharging sinus that becomes very difficult to close.
Cold abscesses in skeletal TB are managed conservatively with ATT in most cases. Aspiration (aspiration under NEGATIVE pressure, NOT open incision) may be used for large symptomatic abscesses. Open incision and drainage is CONTRAINDICATED because it creates a chronic sinus that is difficult to heal.
The cardinal rule: DO NOT incise a cold abscess. Open incision creates a chronic sinus. Management = ATT + aspiration if needed (under strict aseptic conditions).
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A 25-year-old female presents with insidious onset left knee pain and swelling for 8 months. On examination there is a doughy feeling synovial thickening (Rice bodies palpable), 15° flexion deformity, and wasting of quadriceps. Which of the following pathological findings would confirm the diagnosis of TB of the knee joint?
Correct. Definitive diagnosis of TB arthritis requires histopathological demonstration of caseating granulomas with Langhans giant cells, or microbiological confirmation (culture or CBNAAT) positive for M. tuberculosis from synovial tissue or fluid.
Histopathology of synovial biopsy showing caseating granulomas with Langhans giant cells is diagnostic of TB. Culture on Lowenstein-Jensen medium growing Mycobacterium tuberculosis is the gold standard but slow. CBNAAT (GeneXpert) on tissue or aspirate provides rapid diagnosis with drug sensitivity.
TB joint diagnosis requires histopathology (caseating granuloma + Langhans cells) or microbiology (positive culture/CBNAAT for M. tuberculosis). The other options describe features of pyogenic arthritis, rheumatic fever, or reactive arthritis.
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A 45-year-old farmer is diagnosed with caries spine at L2–L3 with a large bilateral psoas abscess but no neurological deficit. He lives in a rural area far from a tertiary centre. He is started on ATT 2HRZE/4HR. After 3 months, the abscess has enlarged on repeat imaging. Which is the most appropriate intervention?
Correct. For a large psoas abscess enlarging on ATT, percutaneous aspiration (ultrasound or CT-guided) is the preferred minimally invasive intervention. It reduces the abscess burden, relieves pressure, and sends material for culture and drug sensitivity testing.
A psoas abscess that enlarges on adequate ATT may be aspirated under ultrasound/CT guidance (percutaneous aspiration). Surgical open drainage is reserved for very large, inaccessible, or secondarily infected abscesses. Open incision carries the risk of sinus formation.
Enlarging psoas abscess on ATT → percutaneous aspiration (ultrasound/CT-guided), not open drainage (which risks sinus) and not empirical switch to second-line drugs without sensitivity testing.
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A 50-year-old male with HIV (CD4 60 cells/μL) presents with multifocal bone pain, constitutional symptoms, and X-rays showing lytic lesions at D7, L3 and the proximal femur. Biopsy confirms TB. Which of the following is MOST characteristic of multifocal skeletal TB compared to the typical unifocal disease?
Correct. Multifocal skeletal TB occurs in immunocompromised patients (classically HIV with low CD4 count). It can affect spine and appendicular skeleton simultaneously and radiologically mimics metastatic malignancy, requiring biopsy for diagnosis.
Multifocal skeletal TB (previously called disseminated or 'skip' TB) is more common in immunocompromised patients (HIV, malnutrition, steroids). It may present without the classic cold abscess or disc involvement seen in unifocal spinal TB, and can mimic metastatic malignancy radiologically.
Multifocal TB = more common in immunocompromised (HIV, malnutrition) + can involve any bone + mimics mets on imaging. Standard ATT (2HRZE/4HR) is still the treatment; surgery is for complications only.
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A 19-year-old woman has been treated for 3 months for TB of the right knee. She is now pain-free but has developed 25° fixed flexion deformity and fibrous ankylosis. What is the MOST appropriate long-term management?
Correct. After completing ATT and confirming disease quiescence, reconstructive options include arthrodesis (fusion in functional position — reliable, durable) or TKA after a disease-free interval of at least 10 years in carefully selected patients.
Once TB disease has been controlled with ATT and the disease enters the healed/healing phase, late reconstructive surgery becomes an option. For TB knee with fibrous ankylosis, arthrodesis (fusion in functional position) or — in selected modern patients — total knee arthroplasty (TKA) after disease quiescence of at least 10 years, provides a functional outcome.
Reconstructive surgery for TB joint sequelae is deferred until after ATT completion and disease quiescence. Arthrodesis in functional position is the classical reconstructive procedure; TKA may be considered after a prolonged disease-free period.
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A 8-year-old boy presents with painful limp, inability to bear weight on the right leg, and a mildly elevated temperature (37.8°C) for 3 months. Hip X-ray shows periarticular osteoporosis and early superior joint space narrowing on the right. ESR is 55 mm/hr. Mantoux test shows 16 mm induration and HRCT chest reveals a calcified hilar node. Which INITIAL investigation would BEST guide your decision between TB hip and transient synovitis?
Correct. MRI with contrast delineates synovial thickening, bone marrow signal change, and cartilage integrity — findings that differentiate TB from transient synovitis. Ultrasound-guided aspiration for AFB smear, culture, and CBNAAT provides microbiological confirmation.
Transient synovitis resolves in days to weeks; TB hip persists for months. ESR >20, fever >37.5°C, refusal to bear weight, and WBC >12,000 are the Kocher criteria used to distinguish septic arthritis from transient synovitis — but in subacute cases, MRI with contrast (showing synovial enhancement and bone marrow oedema) + synovial fluid analysis or biopsy best differentiates TB from transient synovitis.
MRI (synovial enhancement, bone erosions, marrow oedema) + synovial fluid AFB analysis (smear/culture/CBNAAT) best differentiates TB hip from transient synovitis. CRP alone is non-specific; repeat X-ray adds little in early disease; empirical ATT without confirmation is poor practice.
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