Patella Osteomyelitis Mimicking Sinding-Larsen and Johansson Apophysitis: A Pitfall Not to Miss

BACKGROUND: Diagnosis of bony infection remains difficult during childhood. Osteomyelitis of the patella (OMP) is rare and produces few symptoms and no fever. A high level of suspicion is needed to avoid missing this uncommon type of bone infection. METHODS: / RESULTS: We report an acute osteomyelitis of the patella treated by joint and patella puncture aspiration followed by antibiotics in a 12-year-old healthy boy. Clinical and radiological findings, orthopedic follow-up, and clinical outcome are presented. CONCLUSION: Making a diagnosis of acute osteomyelitis of the patella can be challenging especially in the pediatric population, as it produces few specific symptoms with mostly nonspecific biologic anomalies. The paucity in specific signs and symptoms, accompanied by the rare occurrence, often leads to incorrect initial diagnosis, such as overuse injury or apophysitis. Clinical examination with high suspicion for patella infection is key. Radiological exams including MRI are the main components of the adequate imaging studies. Computed tomography may be an excellent addendum to better visualize any bony lesion within the patella. Bone aspiration or biopsy is essential to confirm the diagnosis and offers a first step in the treatment of this infection, which can then be successfully treated with a normal course of antibiotics.