J Korean Neurosurg Soc.  2012 Dec;52(6):541-546. 10.3340/jkns.2012.52.6.541.

Customized Cranioplasty Implants Using Three-Dimensional Printers and Polymethyl-Methacrylate Casting

• Kim BJ
• Hong KS
• Park KJ
• Park DH
• Chung YG
• Kang SH

• KMID: 1426264
• DOI: http://doi.org/10.3340/jkns.2012.52.6.541

Abstract

OBJECTIVE
The prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting.
METHODS
A total of 16 patients with large skull defects (>100 cm2) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect.
RESULTS
The median operation time was 184.36+/-26.07 minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously.
CONCLUSION
Customized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects.

Keyword

Decompressive craniectomy; Reconstructive surgical procedure; Computer-aided design; Polymethyl-methacrylate

MeSH Terms

Computer-Aided Design
Decompressive Craniectomy
Follow-Up Studies
Fungi
Humans
Methylmethacrylate
Polymethyl Methacrylate
Reconstructive Surgical Procedures
Skull
Tomography, Spiral Computed
Methylmethacrylate
Polymethyl Methacrylate

Figure

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  Fig. 1 Three-dimensional (3D) image of a master implant in a unilateral cranial defect. Preoperative axial 1-mm CT data are converted to 3D images (A). The image of the implant is generated by a digital subtraction mirror-image process (B) and developed into the 3D implant model (C).

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  Fig. 2 Implant image generation by the merge technique for bilateral cranial defects. Three-dimensional (3D) images are reconstructed with routine CT data before craniectomy. The images show an irregular stair-like surface (A). The 3D implant model is transformed with a smoothing technique (B). A 3D image of the bilateral cranial defect is reconstructed with an axial 1-mm spiral CT scan (C) and merged with previous images of the precraniectomy CT scan (D).

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  Fig. 3 A mold image is developed by using the three-dimensional implant image (A), and applied to construct cranioplasty image in the computer simulation (B).

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  Fig. 4 By using three-dimensional printers (Spectrum Z510 3D printer from Z Corp.) (A), molds are prefabricated through powder depositional modeling processes (B). Intraoperatively, the polymethyl methacrylate implant is made by the prefabricated mold and casting (C).

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  Fig. 5 Axial and coronal postoperative CT scans show a symmetrical contour and curvature of the cranium compared to a contralateral normal one.

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  Fig. 6 Three-dimensional CT images demonstrate unilateral (A) and bilateral (B) reconstruction of large cranial defects.

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