We report the case of a 47-year-old female patient with rheumatoid arthritis and HIV infection presenting with a 3-week history of a painful swollen knee, increased serum inflammatory markers, and a low CD4 lymphocyte count. The diagnosis of TB arthritis was made by synovial fluid culture, GeneXpert/PCR, and confirmed by histopathology of a synovial biopsy. A mini literature review suggests that although HIV infection is associated with extrapulmonary TB, osteoarticular TB is a relatively unusual presentation in an HIV positive patient. The diagnostic utility of the GeneXpert test is explored. We also describe the patient's good response to an intra-articular corticosteroid injection in combination with standard anti-TB therapy.