Revisiting the important role of magnetic resonance imaging (MRI) in long bone acute osteomyelitis: A case report of methicillin resistant Staphylococcus aureus acute tibial osteomyelitis with conventional radiography, computed tomography, and MRI.

The tibia is an atypical site of osteomyelitis (OM) in adults, and patients with this infection experience a significant degree of morbidity as well as the need for prolonged aggressive antibiotic therapy. The early diagnosis of OM remains challenging, and often relies on imaging modalities which are of variable sensitivity. We present a case of a 49-year-old male with a methicillin resistant Staphylococcus aureus (MRSa) left tibial OM, contiguous left knee septic arthritis, and concurrent bacteraemia. Eight days after the onset of pain in the left knee and lower limb, conventional radiography and computed tomography (CT) imaging had only subtleties of a soft tissue collection and a knee effusion. A MRI demonstrated significant involvement of his tibial bone with a collection, from which surgical specimens confirmed MRSa. This case demonstrates the difficulty of diagnosing early acute OM with conventional radiography and CT imaging, even after a week of symptoms in the affected limb. Given the poor sensitivity of conventional radiography and CT in the diagnosis of early acute OM, this case report illustrates how MRI is the imaging modality of choice in this setting.