Customized Polymethylmethacrylate Cranioplasty Implants Using 3-Dimensional Printed Polylactic Acid Molds: Technical Note with 2 Illustrative Cases.

Abstract

Prefabricated customized cranioplasty implants are anatomically more accurate than manually shaped acrylic implants but remain costly. The authors describe a new cost-effective technique of producing customized polymethylmethacrylate (PMMA) cranioplasty implants with the use of prefabricated 3-dimensional (3D) printed molds. The first patient had a left frontal cranial defect after a craniotomy for a glial tumor. A 3D image of his skull was obtained from axial 0.6-mm computed tomography (CT) scan images. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of his cranium as a model. The second patient had a bifrontal defect after the resection of an infected customized polyetheretherketone implant. A 3D image of the infected implant was directly obtained from an axial 0.6-mm CT scan before discarding it. The images were then used to produce for each patient a mold of the external surface of the cranium using a low-cost polylactic acid 3D printer. Intraoperatively, each mold was put in a sterile bag and then used to cast a customized PMMA implant subsequently trimmed before fixation. Both patients had excellent cosmetic results and underwent postoperative CT scans that showed excellent restoration of the symmetrical contours of the cranium. No neurologic or infectious complications occurred over a 6-month follow-up for either patient. Making customized PMMA cranioplasty implants via 3D printed polylactic acid molds is a cost-effective technique for delayed reconstruction of various cranial defects.