Corrective osteotomies using patient-specific 3D-printed guides: a critical appraisal.

INTRODUCTION: Over the last decade, the technique of 3D planning has found its way into trauma surgery. The use of this technique in corrective osteotomies for treatment of malunions provides the trauma surgeon with a powerful tool. However, this technique is not entirely straightforward. We aimed to define potential pitfalls of this technique and possible solutions to overcome these shortcomings.

MATERIALS AND METHODS: Ten patients with either a uni-, bi- or triplanar malunion of the long bones were included in this study. These patients were divided into three groups: a weight-bearing group and a non-weight-bearing group, the latter was divided into the humerus group and the forearm group, subsequently. 2D correction parameters were defined and compared within every group, as well as the interpretations of 3D visualization.

RESULTS: The weight-bearing group revealed an undercorrection for almost all clinical measurements of the femur and tibia, while there was adequate matching of the osteotomies and of screw entry points in all cases. In the humerus group, coronal correction angles were nearly perfect in all cases, while axial and sagittal correction rates, however, differed substantially. Screw entry points and osteotomies were all at the level as planned. The forearm group showed undercorrection in multiple planes while there were good matching entry points for the screw trajectories.

DISCUSSION: Four major pitfalls were encountered using the 3D printing technique: (1) careful examination of the planned guide positioning is mandatory, since suboptimal intra-operative guide positioning is most likely the main cause of the incomplete correction; (2) the use of pre-drilled screw holes do not guarantee adequate screw positioning; (3) translation of bone fragments over the osteotomy planes in case of an oblique osteotomy is a potential hazard; (4) the depth of the osteotomy is hard to estimate, potentially leading to extensive cartilage damage.