Which of the following constitutes the Phemister triad of tuberculous arthritis?
- A Periarticular sclerosis, subchondral cysts, and rapid joint space loss
- B Juxta-articular osteoporosis, marginal erosion, and gradual joint space narrowing ✓
- C Marginal erosion, periosteal reaction, and soft tissue calcification
- D Juxta-articular osteoporosis, ankylosis, and periosteal new bone formation
Correct answer: B. Juxta-articular osteoporosis, marginal erosion, and gradual joint space narrowing
Explanation
The Phemister triad describes the three radiological hallmarks of tuberculous arthritis: juxta-articular osteoporosis from disuse and hyperaemia, marginal erosions at the bare areas of the joint, and gradual narrowing of the joint space due to slow cartilage destruction. Rapid joint space loss is typical of pyogenic septic arthritis, which destroys cartilage quickly through proteolytic enzymes, whereas tuberculosis destroys cartilage slowly.
Reference: Textbook of Orthopaedics, Ebnezar, 5th ed.
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