Osteoarticular TB specimen yield rates. Large joint analysis at a single centre

Tuberculosis (TB) remains endemic in South Africa. The spine, hip, and knee joints are common extra-pulmonary TB sites. Sound history taking, clinical examination, and basic laboratory and pathological tests remain key important steps in osteoarticular TB diagnosis. In our resources-stricken context cost is everything, if we can make a diagnosis cheaply that would go a long way. The diagnostic yield of standard laboratory tests compared to a real-time polymerase chain reaction (PCR) for osteoarticular TB diagnosis in a single orthopaedic unit has not been analysed. We conducted a retrospective record review of extra-spinal osteoarticular TB infection at our hospital from 01 June 2016 to 31 December 2021. Patient demographics, clinical history, and laboratory test results were analysed. A total of 34 cases were identified, with 32 of the cases being articular and two osseous involvement. The knee was the most common joint affected followed hip joint. Acid Fast Bacilli were detected in 32% of cases with microscopy, while TB culture was positive in 29% of samples. Histopathological examination and real-time PCR diagnosed TB in 66% and 63% of the cases, respectively. Our findings suggest that in the right context of a suggestive history and examination, histological analysis is as good as PCR for diagnosing osteoarticular TB.