Disseminated Pulmonary and Knee Tuberculosis With Phemister Triad

Abstract Introduction Bone and joint infections are uncommon sites for tuberculosis. The knee is the third most frequently affected site after the spine and hip. Case report A 62-year-old woman was referred to the orthopaedic clinic with a swollen and painful left knee. There was no history of trauma, symptoms of respiratory infection, or involvement of any other joints. On physical examination, her knee was swollen, and painful and had restricted range of motion in all planes. Blood investigations revealed an elevated C-reactive protein (CRP) of 464 mg/dL and an erythrocyte sedimentation rate (ESR) of 126 mm/h.The plain radiographs of her left knee (Figure 1.1) showed extensive subcutaneous soft tissue swelling and joint distension. Magnetic resonance imaging (MRI) (Figure 1.3) confirmed diffuse synovial thickening and large joint effusion.The histology of the synovial biopsy showed non-necrotizing granulomatous inflammation with no malignancy. TB Mycobacteria Growth Indicator Tube (MGIT) culture of the synovial biopsy was positive. The Hain MTBDR plus assay confirmed the presence of M. tb and susceptibility to Isoniazid and Rifampicin. Bacterial and mycology cultures were both negative.During her follow-up visit, she reported new-onset respiratory symptoms, cough and shortness of breath with constitutional symptoms. A sputum for The Xpert MTB/RIF Ultra confirmed pulmonary TB. A chest radiograph (Figure 1.2) demonstrated randomly distributed bilateral nodular infiltration, air bronchograms, and right middle zone consolidation abutting the horizontal fissure and small bilateral pleural effusions. These findings were highly suggestive of pulmonary TB. The patient was prescribed standard TB treatment. Discussion In classic cases such as this, knee TB may present with a phemister triad which comprises subarticular erosions, juxta-articular osteoporosis, and narrow joint space as shown by coloured arrows in (Figure 1.1). In South Africa, the spine is the most common site for musculoskeletal TB. However, this case highlights the uncommon but increasingly recognized presentation of monoarticular tuberculous arthritis of a joint. It is also important to highlight that only around half of patients with skeletal TB would exhibit overt respiratory symptoms and, thus, the diagnosis would depend on a high index of suspicion in patients residing in TB-endemic countries especially when there is the presence of constitutional symptoms as was the case here. The treatment of musculoskeletal TB follows the same principles as those for pulmonary TB. In conclusion, TB must be considered as a differential for mono-articular arthritis even when pulmonary symptoms are absent, especially in high-burden countries like South Africa.