Sonography of acute osteomyelitis in rabbits with pathologic correlation

Rationale and Objectives. Ultrasonography (US) has a potential role in the diagnosis of osteomyelitis. The purpose of this study was to determine the characteristic sonographic features of acute osteomyelitis and correlate th em with pathologic findings. Materials and Methods. An experimental model of acute osteomyelitis was pro duced in the tibiae of 20 rabbits. Daily US and plain radiography were perf ormed for 2 weeks. The authors evaluated periosteal reaction. subperiosteal fluid col lection, and soft-tissue changes seen with US. A hypoechoic band and a hyperechoic line lying along the cortex were considered positive sig ns of subperiosteal fluid collection and periosteal reaction, respectively. The findings of periosteal reaction were compared for US and radiography, and pathologic findings were also correlated. Results. The most common sonographic finding was a hypoechoic band along th e cortex (21 [75%] of 28 tibiae), usually associated with a linear perioste al reaction (20 [71%] of 28). This juxtacortical abnormal echogenicity corr esponded to periosteal elevation with loose fibrovascular connective tissue and granulation, associated with subperiosteal abscess formation. The peri osteal reactions were detected with US before they were seen on radiographs . The periosteum showed gradual thickening during the disease process. In 5 0% of infected tibiae, inflammation or abscess formation was observed in th e surrounding soft tissue. Conclusion. US readily demonstrates juxtacortical abnormal echogenicity and soft-tissue infection related to acute osteomyelitis. The abnormal echogen icity correlated well with the pathologic findings of periosteal reaction a nd subperiosteal abscess.