Presentation
One week of lower back pain, right buttock pain. Unable to mobilize today.
Patient Data
There is symmetric loss of right hip joint space with loss of definition of the subchondral bone plate of the acetabulum compared to the left hip. No fracture or subluxation detected. Alignment is unremarkable.
A moderate-sized right hip joint effusion is demonstrated.
Loss of right femoroacetabular joint space with extensive low T1/high fluid-sensitive signal within the acetabulum, the right femoral head, neck and inter-trochanteric region with focal areas of intramedullary contrast enhancement within the acetabulum and the proximal femoral diaphysis.
Subchondral bony erosion.
Large multiloculated thick rimmed enhancing joint effusion. Direct involvement of the adjacent iliopsoas without superior extension into the pelvis or retroperitoneum.
Thickening and fluid seen along the investing fascia of the quadriceps compartment of the thigh.
Conclusion:
Septic arthritis and osteomyelitis of the right hip joint with a multiloculated thickly enhancing joint effusion and adjacent extension into the right iliopsoas most consistent with tuberculous septic arthritis.
US-guided hip aspiration was performed.
MICROSCOPY Auramine-Rhodamine stain: no acid-fast bacilli detected. A negative acid-fast smear result does not exclude the presence of Mycobacterium species.
ANTIGEN TESTING (ON ISOLATE) MPT64 antigen identification test: M tuberculosis complex detected.
NUCLEIC ACID TESTING (ON ISOLATE) Mycobacterium spp by DNA probe: positive for M tuberculosis complex nucleic acid.
MYCOBACTERIUM CULTURE SCREEN MGIT bottle <11 days: positive.
MYCOBACTERIAL CULTURE
1. Mycobacterium tuberculosis isolated.
Case Discussion
Mycobacterium tuberculosis septic arthritis often affects and the knee or hip and usually results from reactivation of previous infection. It can present without other symptoms of tuberculosis. Initial smears are often negative and synovial culture is positive in ~80% of cases 1.
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