[Relation of necrosis to outcome and site of fracture in scaphoid pseudarthrosis]

Usually, untreated scaphoid fractures lead to non-union and partial or complete avascular necrosis. The purpose of our study was to examine the influence of location and fracture line on the pattern of necrosis. Therefore, 85 patients with scaphoid non-union were examined by enhanced highfield MRI. Fractures were classified by location and fracture line. A staging system based on signal intensity in T1-weighted spin-echo sequences in enhanced MRI was used to evaluate extent and location of avascular necrosis, which was found in 81% of our patients. In our patients, viability of the scaphoid was independent of the fracture line without dominance of vertical oblique fractures (2%). Based on our staging system, signal intensity as a sign of fragment viability was reduced in the proximal fragment in 46 patients, whereas in eight patients the distal fragment showed reduced viability. In 26 patients, no difference was found between proximal and distal fragments. Fractures proximal to the transition of middle to distal third showed less viability of the proximal fragment, not dependent of how proximal the fracture was seen. In triple fractures (6%) signal intensity of scaphoid bone was more reduced in enhanced MRI.