Primary patella tuberculosis mimicking pre-patellar bursitis: A case report and review of the literature

Introduction and importance: The Patella is very rare site for tuberculosis (TB). The knee is the third most common site for skeletal TB. The incidence of patella TB being 0.09 to 0.15%. Case presentation: We report a case of primary tuberculous osteitis isolated from the patella. The complaint was a mixed knee pain without notion of trauma. The CT showed a large osteolysis of the upper half of the patella. The diagnosis was established on the histological study after biopsy. The patient was operated by a medial approach without arthrotomy and the pathological tissue was resected and curetted. Complementary anti-bacillary antibiotic treatment was administered for 12 months. At the last clinical control, the knee was free and painless, and we had no recurrence. Clinical discussion: Aitken reported the first case in literature in 1933. The initial signs and symptoms are nonspecific and sometimes confounded by a coincidental history of trauma. It is difficult to diagnose TB of patella in early stages because there are no constitutional symptoms. Sometimes serological parameters are inconclusive. CT scan can help if the osteolysis contained a central bone sequestration, bordered by peripheral sclerosis. Confirmation of patellar tuberculosis is made on biopsy. Conclusion: The tuberculous localization in the patella is rare and it can pose a problem of differential diagnosis with other affections, in particular infectious and tumors. It should always be kept in mind, especially in the face of a picture of pre-patellar bursitis which progresses slowly and whose biological inflammatory syndrome is not straightforward.