Idiopathic osteonecrosis of the scaphoid (Preiser's disease) - MRI gives new insights into etiology and pathology

Objective: To describe the imaging signs of idiopathic osteonecrosis of the scaphoid (Preiser's disease) and to differentiate the findings from scaphoid nonunion. Material and methods: 10 patients (4 men, 6 women, mean age 36.9 years) with radial-sided wrist pain were identified to suffer from primary osteonecrosis of the scaphoid. Imaging methods included radiograms in all cases, CT imaging in 9 cases, and contrast-enhanced MRI in 7 cases. In CT and MRI, images were also acquired in the sagittal-oblique plane for depicting the scaphoids in the entire longitudinal extension. Follow-up examinations were performed in 5 patients, two of them underwent surgery with pedicled bone grafts. Results: In all patients, both osteosclerosis and lesions of the bone marrow were most intensive at the proximal scaphoid pole. A three-layered architecture was found. The zone of osteonecrosis was located most proximally, followed by a zone of repair in the middle, and the zone of viable bone marrow in the distal part of the scaphoid. In contrast to scaphoid nonunion, pathological fractures were exclusively located within the zone of osteonecrosis in 8 cases. Applying morphologic criteria, three stages of Preiser's disease were discernible. The initial stage (proximal osteosclerosis, but unaltered shape of the scaphoid), the advanced stage (pathologic fractures, volume loss of the proximal pole), and the final stage (osteonecrosis of the entire scaphoid). Conclusion: Pathoanatomy of Preiser's disease and the differentiation into three zones of bone marrow viability can be explained with the retrograde blood supply of the scaphoid. In its natural course, three different stages can be depicted with the initial stage seen only in MRI.