Tuberculous arthritis is mono-articular arthritis and spares no joints. Large joints like the hip and knee are the most commonly involved joints.

Musculoskeletal involvement is through hematogenous spread often from a primary focus. 50% show no pulmonary radiographic changes. 

The mycobacterium lodges itself in the joint synovium or the metaphysis leading to marked joint effusion and thickening of the synovial membrane. Then the granulation tissue expands inwards from the joint periphery causing erosion at the bare areas of bone and the surface of the articular cartilage. In untreated cases, further erosion occurs and progressive of the destruction of the articular surfaces. Later para-articular soft tissue extension may occur with the formation of cold abscesses and sinuses.

Synovial thickening shows low to intermediate signal on T2 weighted images. Joint effusion content includes; internal debris, septations, loose bodies and hemosiderin deposition.

Differential diagnosis: Pigmented villonodular synovitis (PVNS).

Synovial biopsy histopathology was of tuberculosis.