Case Report of Post-Traumatic Monoarticular Tuberculosis of the Knee in a Healthy Young Adult: Diagnostic and Therapeutic Challenges in a Non-Endemic Setting.

Introduction: Tuberculosis (TB) arthritis, particularly in the knee, is a rare condition with significant diagnostic challenges, especially in regions with low TB incidence. This case report presents the first documented instance of native knee TB arthritis in Ireland, highlighting the necessity for increased awareness and a multidisciplinary approach in diagnosing this uncommon disease. Case Report: A 27-year-old healthy male, originally from India, and living in Ireland, presented with non-specific left knee pain for 3 weeks, initially diagnosed as a soft-tissue injury. After a subsequent traumatic left patellar fracture that required surgical fixation, his recovery was complicated by persistent knee swelling and limited range of motion. Following 12 months of delayed recovery, all implants were removed from his knee, and physiotherapy was initiated. When he was still symptomatic 10 months later, further investigations were required. Higher-order imaging revealed marked degenerative changes in the knee joint along with extensive synovitis. Following multidisciplinary team input, he underwent biopsies of his tibial plateau as well as synovial tissue and joint fluid. Histology of tissue demonstrated granulomata, and anti-tuberculous therapy was initiated before tissue culture from the index biopsy later confirmed Mycobacterium TB (MTB). Clinical response to treatment was marked, with improvement in symptoms and functionality. After completing the course of treatment, the patient had another setback when he sustained a comminuted left distal femur fracture following a low-trauma fall. During the open reduction and internal fixation for this fracture, tissue samples taken intraoperatively confirmed complete resolution of granulomatous inflammation. Intraoperative tissue was culture negative for MTB. This confirms successful microbiological and clinical cure of the infection. Conclusion: This report underscores the critical importance of considering TB arthritis in patients with persistent knee pain, particularly in patients who have migrated from high-incidence countries. It provides insight into the diagnostic complexities and emphasizes the role of tissue biopsy for histological analysis and mycobacterial tests in confirming the diagnosis. The findings from this case contribute significantly to the orthopedic literature and foster awareness of TB arthritis, advocating for timely diagnosis and interdisciplinary cooperation in managing rare diseases.