Tuberculosis of the knee complicating seronegative arthritis.

To the Editor: The diagnosis of tubercular arthritis can be challenging, particularly in the presence of confounding factors such as preexisting arthritis. We describe one such case. A 22-year-old South Asian woman presented to the Orthopaedic Service with an intermittently painful and swollen right knee. The symptoms dated from a fall 7 years previously. On examination in the Orthopaedic Clinic, blood test results and knee radiograph were normal. A synovial fluid aspirate was obtained; standard culture was negative and no acid-fast bacilli (AFB) were isolated from prolonged culture. On her entry to the UK 12 months earlier, a routine Heaf…