Three-dimensional preoperative planning for adult acute plastic bowing of the ulna

CASE: We report a case of adult acute plastic deformity of the ulna. Ulnar osteotomy was planned using 3-dimensional (3D) surface data from both injured and intact sides using surface registration technique. Opening wedge osteotomy was planned to correct the position of the ulnar fovea with respect to the proximal ulna. The position of the plate and direction of the screws were decided preoperatively. The operation was performed with reference to a 3D-printed, reduced model. The preoperatively limited pronation and supination of the patient were significantly improved as of 2 years postoperatively. Our preoperative method has several advantages. The risk of nonunion is low because the hinge-side bone cortex remains intact. The surgical procedure is simple, because plate position and direction of drilling are both decided preoperatively. In addition, correction of alignment can be achieved gradually by inserting screws through the plate and checking the range of motion of the forearm. CONCLUSION: Our 3D preoperative simulation aimed to correct the rotational axis of the forearm. The surgical procedure was greatly facilitated using the 3D-printed, reduced model for reference.