Which of the following constitutes the Phemister triad, classically described in chronic infective arthritis including tuberculosis?
- A Periosteal reaction, central metaphyseal erosion, and rapid loss of joint space
- B Sequestrum, involucrum, and cloaca formation
- C Juxta-articular osteoporosis, marginal osseous erosions, and gradual narrowing of the joint space ✓
- D Soft tissue swelling, pathological dislocation, and fibrous ankylosis
Correct answer: C. Juxta-articular osteoporosis, marginal osseous erosions, and gradual narrowing of the joint space
Explanation
Phemister described three features of chronic low-grade joint infection such as tuberculosis: juxta-articular osteoporosis, marginal erosions at the bare areas of the joint, and slowly progressive narrowing of the cartilage space. Marked periosteal reaction and rapid destruction of the joint space are features of acute pyogenic arthritis, which makes option A the best distractor but incorrect.
Reference: Apley's System of Orthopaedics and Fractures, 10th ed.
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