A Comparison of Non-vascularized Bone Grafting and Internal Fixation in the Treatment of Unstable Scaphoid Waist Nonunion

Background: When nonunion of scaphoid waist is treated with non-vascularized bone grafting with internal fixation, bony union would be affected not only type of bone graft but also fixation method. Thus, we attempted to investigate whether the bony union depends on how surgeons combine bone grafting and internal fixation. Methods: We treated 38 consecutive patients with unstable nonunion of scaphoid waist. The patients were treated with one of three types of non-vascularized bone grafting and internal fixation by random sampling, regardless of the configuration of the nonunion; cortico-cancellous bone grafting with Kirschner wire (K-wire) fixation group (12 cases), cortico-cancellous bone grafting with headless compression screw fixation group (13 cases) and cancellous bone grafting with K-wire fixation group (13 cases). We compared "union rate" and "time to union" between groups with statistical analysis. We described clinical features of "failure to union" cases. Results: The mean time to union of cancellous bone grafting with K-wire fixation group was significantly shorter than those of other groups. There was also significant difference in mean time to union between cortico-cancellous bone grafting with K-wire fixation group and cancellous bone grafting with K-wire fixation group (when the type of bone grafting was different). All the "failure to union" cases were sclerotic (Herbert type D2) nonunion treated by cortico-cancellous bone grafting. Conclusions: When treating unstable nonunion of scaphoid waist with non-vascularized bone grafting with internal fixation, cancellous bone grafting with K-wire fixation seems to be advantageous in terms of mean time to union. It seems that both bone grafting and fixation method affected "mean time to union" but the type of bone grafting was more influential in achieving union. The failure to union might be frequent in case of Herbert type D2 nonunion combined with cortico-cancellous bone grafting.