Knee tuberculosis: A misleading clinical entity (case report)

INTRODUCTION: Bone and joint infections are rare localizations of tuberculosis, and its diagnosis is challenging. The atypical clinical presentation may lead to delayed diagnosis and severe complications. CASE PRESENTATION: We report the case of a 72-year-old female diagnosed with tuberculosis of the knee. She was complaining of progressive right knee pain and swelling without systemic signs. She was misdiagnosed as having a flare-up of osteoarthritis, which led to a delayed diagnosis and a septic subluxation of the knee. We performed a knee arthrotomy, lavage, and stabilization with an external fixator. The microbiologic tests did not isolate any germs. However, a histological examination confirmed the diagnosis by revealing a caseating granuloma surrounded by epithelioid cells. The patient treated with anti-tuberculosis therapy had a good evolution. Three months post-surgery, the external fixator was replaced with a removable knee brace. DISCUSSION: Osteoarticular tuberculosis is often caused by the hematogenous route. The lack of specificity in clinical and radiological signs makes the diagnosis difficult, especially at the early stage, leading to delays in diagnosis and complications. Nevertheless, the recognition of predisposing factors to tuberculosis, with persisting symptoms despite treatment, should draw the intention of further investigation. The treatment of osteoarticular tuberculosis is primary medical with antituberculosis chemotherapy. However, surgical treatment is reserved for specific indications and mostly to treat complications. CONCLUSION: The lack of specificity in clinical and radiological signs in osteoarticular tuberculosis may mislead the physician. Nevertheless, focusing on predisposing factors, especially in endemic areas, may guide diagnosis and avoid complications.