gms | German Medical Science

Objectives/Interrogation: Surgery of scaphoid nonunion is still challenging especially in case the nonunion site is proximal and wedge bone graft is needed. For proper fixation, we have tried preoperative simulation with 3D guidance obtained by CT. We report a case of retrograde fixation combined with wedge bone graft for proximal scaphoid nonunion with humpback deformity in which the target point is very restricted.

Methods: For a case of proximal small fragment of scaphoid non-union with humpback deformity (Figure 1 [Fig. 1] left, center), we simulated correction of the deformity with use of contralateral 3D-CT images. We simulated two patterns of guide-pin insertion; After correction by wedge bone graft, 1) usual guide-pin insertion from the scaphoid tubercle and 2) trans-trapezium insertion. This simulation showed the target of the screw was strictly limited in the way of 1), although proper placement of the guide-pin centering both the wedge bone graft and tiny proximal fragment in the way of 2) (Figure 1 [Fig. 1] right).

Results and Conclusions: At the operation, the guide-pin was inserted in the way of 2) from mid-trapezium according to the preoperative simulation and reproduced CAD models (Figure 2 [Fig. 2] left, center). It was penetrated to dorsal wrist and a cannulated headless screw was inserted successfully in retrograde fashion (Figure 2 [Fig. 2] right). 3D simulation of guide-pin and screw placement simulated by preoperative CT was quite useful for such a difficult case in which the targeting fragment is small and bone graft insertion is also needed.