Avascular necrosis after scaphoid fracture: a correlation of magnetic resonance imaging and histology.

In this study 12 male patients with fractures of the middle third of the scaphoid had an magnetic resonance imaging study before open reduction and internal fixation in conjunction with bone grafting of the scaphoid. The patients' average age was 27 years (range, 17 to 37 years). At the time of surgery biopsy specimens were obtained from both the proximal and distal poles of the scaphoid. The length of time before surgery ranged from a minimum of 1 1/2 months in recently displaced fractures to a maximum of 10 years in established nonunions. Results of the biopsy showed that six patients had avascular necrosis noted in the proximal pole fragment. In three of these six patients avascular necrosis was confirmed by the absence of tetracycline labeling despite positive uptake noted in biopsy specimens from the bone graft site; the other three patients did not receive tetracycline labeling. Magnetic resonance imaging showed that all six of the patients with biopsy specimens of the proximal poles showing avascular necrosis demonstrated decreased signal intensity in the proximal pole fragment, whereas the plain radiographs demonstrated changes in the proximal pole in only three of the six patients. A decreased signal intensity from the proximal pole of the scaphoid may indicate a poor prognosis inasmuch as only three of the six patients had healing of the fracture even with bone grafting and internal fixation.