Osteosynthesis of carpal scaphoid nonunion with interpositional bone graft and Kirschner wires: a 3- to 6-year follow-up.

Background: Malreduced or neglected unstable carpal scaphoid fractures may lead to nonunion, which is often difficult to treat and carries the risk of carpal instability and degenerative arthrosis. Here, we describe a new sandwich method, which takes advantage of minimal dissection and has promising results. Methods: From 1989 through 1992, we treated 39 patients with scaphoid nonunion by using the sandwich method that consisted of a wedge corticocancellous strut graft and numerous cancellous bone chips. Divergent Kirschner wires were used for fixation of reduction. We retrospectively review 26 scaphoids with follow-up periods of 3 to 6 years. The functional outcome was evaluated with modification of the Mayo Wrist Scoring Chart. The radiographs were analyzed, and tomographs were used for confirmation of osseous union. Results: All 26 scaphoids united within 4 months. The carpal instability and bumpback deformity were corrected. In all cases, the functional results were either good or excellent. Conclusion: Interpositional bone grafts corrected scaphoid angulation and length. Divergent multiple pinning rather than screws avoids unwanted shearing and rotational force during application and provides stable fixation with minimal dissection. Most of scaphoid nonunions in our series were the oblique type in which the lag screw never created perfect compression because of a shearing force.