Bacterial Osteomyelitis in the Lower Extremities: Analysis of Histology and MRI Findings in a Case-Control Pilot Study.

Osteomyelitis, particularly affecting the lower extremities, is a serious and increasingly common complication. Accurate diagnosis is essential for successful treatment, yet standardized evidence-based protocols are lacking and diagnostic knowledge remains limited. This study aimed to identify characteristic histological and MRI findings in osteomyelitis to support diagnostic accuracy and guide treatment decisions. In a prospective case-control pilot study conducted from February 2020 to January 2021, all patients with suspected osteomyelitis of the lower limbs were included. Each underwent contrast-enhanced MRI and sampling for microbiological and histological analysis. Findings from five confirmed osteomyelitis cases were compared to five controls where osteomyelitis was ruled out. All osteomyelitis cases showed typical MRI signs, including contrast-enhancing bone edema. Two had early, and two had pronounced intramedullary abscesses. In three controls, contrast-enhancing edema was limited to soft tissue; two showed mild adjacent bone edema. Histologically, all osteomyelitis samples revealed bone fragmentation and inflammatory cell infiltration-absent in controls. Additionally, four showed medullary fibrosis and one fibrin deposits. A comprehensive understanding of both histological and radiological findings is key to effective osteomyelitis treatment. This pilot study is the first to systematically compare MRI and histology findings side by side, offering valuable insights that may enhance diagnostic precision and support evidence-based treatment decisions.