Need: Bone resection using customized 3D-printed guides can improve accuracy, but the technique is still associated with clinically significant errors.Technical solution: We developed an inexpensive optical feedback system (OFS) that compares intraoperative 2D camera images to the pre-operative plan, and accurately depicts the surgeon's guide placement prior to cutting, reducing the errors in resection.Proof of concept: We simulated wide resections of a bone sarcoma on 24 cadaver femurs using 3 cutting guide types. Guide placement was measured using the OFS and compared to CT-scans showing the actual guide position. We carried out a second, controlled study on 20 sawbones, comparing the accuracy of the final bone cuts with and without the surgeon actively using the OFS to adjust the guide position before cutting.Results: For cadavers, in 2 of 3 planes, the position of the jig recorded by the OFS closely matched its actual position, with an accuracy of .87° ± .65°(r = .94) and 1.2° ± 1.3°(r = .81) in the transverse and sagittal planes, respectively. In the second study, OFS increased accuracy of the final cut about the transverse and sagittal planes, respectively by 53.1% (P = .011)/54.7% (P = .04) and 33% (P = .051)/38% (P = .042) in terms of rotation and translation.Next steps: Developing the OFS as a mobile application to reduce the processing time and improve accessibility in the operating room.Conclusion: The OFS could accurately depict the guide placement on the bone and significantly improve the surgical accuracy of 3D printed jigs.
Keywords: 3D printing; computer vision; intra-operative guidance; jig for bone surgery; resection; surgical feedback technique.