Introduction: Desktop 3D printing has not been widely adopted for everyday use in clinical neurosurgical despite numerous benefits and ease. Its use thus far has is for preoperative rehearsal of complex cases, teaching, and prototype development. Prior examples of using hospital based 3D printing have been described but all have used proprietary software: We present a method where freely available open source software and desktop 3D printing can create a customized cranioplasty implant. This technique is easy to learn and can be adopted by any neurosurgical practice.
Methods: Our study obtained exemption from UTMB IRB. The workflow consists of segmenting DICOM images from a noncontrast CT head using Hounsfeld units corresponding to bone within Invesalius 2.0. STL files are then exported from Invesalius into Autodesk Meshmixer 3.1 where convex surface of dura is recreated with a sphere tool. The design is exported to Cura and then printed with the Ultimaker 3D printer in Nylon 680, a FDA-grade material. The print undergoes ethylene oxide gas sterilization and is placed into a sterile pouch. Material such as methylmethacralate or hydroxyapatite can now mixed and poured over the mold.
Results: The print was completed in 67 minutes using an infill of 90%. The total cost of Nylon 680 totaled less than $5. Even including fixed costs of 3D printer, this method provides substantial cost savings over obtaining a custom PEEK implant from a manufacturer averaging $5000-$10000 with only single print. Comparable cosmesis was achieved.
Conclusions: In era of value based purchasing in healthcare, desktop 3D printing with free open source segmentation software has potential to disrupt the way custom cranioplasty are performed.
Patient Care: Our process fits within the practice of medicine paradigm, as it moves the custom 3D cranioplasty arena closer to optimized, affordable, and reliable clinical practice. It counterbalances the progressively unaffordable healthcare system in the United States. In fact, the savings alone from the open market software pay for the cost of a 3D printer. Those with time and patience could theoretically build their own 3D printer from existing open source designs and realize even greater cost savings. In sum, it is a quality improvement project.
Learning Objectives: By the conclusion of this session, participants should be able to:
1) Understand the process of synthesizing a custom hydroxyapatite cranioplasty
2) Implement this streamlined workflow in their neurosurgical practice
References: 1, Pacione D, Tanweer O, Berman P, Harter DH. “The utility of a multimaterial 3D printed model for surgical planning of complex deformity of the skull base and craniovertebral junction.” J Neurosurg. 2016 Nov;125(5):1194-1197. Epub 2016 Mar 4.
2. Hammad M, et al. “Three-dimensional printing in surgery: a review of current surgical applications.” Journal of Surgical Research. 2015 Dec;199(2):512-522.
3. Gasco J, et al. “Neurosurgery simulation in residency training: feasibility, cost, and educational benefit.” Neurosurg. 2013 Oct;73:39-45.