Contour identical implants to bridge mandibular continuity defects - individually generated by LaserCUSING® - A feasibility study in animal cadavers

Abstract

BackgroundAblative tumor surgery often results in continuity defects of the mandible. When an immediate reconstruction using autologous bone grafts is not possible the bridging of the defects with a variety of bridging plates might be achieved. However, those bridging plates have the risk of plate fractures or exposure. Customized titanium implants manufactured using CAD/CAM and the LaserCUSING® technique might be an alternative.MethodsIn the present study, computed tomographies (CT) of porcine cadaver mandibles were generated and transferred into DICOM data. Following, different continuity defects were surgically created in the mandibles. Based on the DICOM data customized titanium implants were manufactured using CAD/CAM procedures and the LaserCUSING® technique. The implants were fixed to the remaining stumps with screws. Subsequently, the accuracy of the reconstructed mandibles was tested using plaster casts.ResultsThe workflow from the CT to the application of the customized implants was proved to be practicable. Furthermore, a stable fixation of the customized implant to the remaining stumps could be achieved. The control of the accuracy showed no frictions or obstacles.ConclusionThe customized titanium implant seems to be a promising approach to bridge continuity defects of the mandible whenever an immediate reconstruction with autologous bone is not possible.

Finite element analysis of customized implant in mandibular reconstruction after tumor resection with and without using customized surgical osteotomy guide

“…In current practices, the most reliable therapy is an instant reconstruction of defects using musculo‐osseous flaps which are microvascularly anastomosed and, harvested from the fibula, iliac crest, or scapula . However, the instant reconstruction of continuity defects of the mandible is not always possible.…”

“…One standard approach is prefabricated metallic reconstruction plates, which plays a vital role in bridging continuity defects and maintaining remaining stumps on accurate site in order to assure ingestion, speech, and patency of the upper airways after ablative tumor surgery of the mandibular region . Clinical experience and previous literature have shown that these commercially available standard reconstruction plates are often subject to excessive stress that may lead to fatigue fractures .…”

“…Bending of the plate might increase the chances of plate fracture from weak points. Plate loosening, fracture, or outside exposure are common complications arising with reconstruction plates . The use of standard plates in simple surgical procedures offers good results in straightforward cases.…”

“…This may create a dead gap between bone and surrounding soft tissues. Less soft tissue might produce high tension which leads to exposure of plate . The plate stability was slightly improved by modifying plate shape and fixture systems.…”

“…In order to avoid the above‐mentioned complications, one promising approach seems to be the application of shape identical, functionally stable implants to reconstruct continuity defects of the mandible . These customized implants conform to the external shape of the defect site (resected bone) that is intended to be replaced . These customized implants could be developed preoperatively to fit exactly by tube‐in‐tube like connections to the remaining stumps.…”