Three-dimensional printing in plastic and reconstructive surgery

Introduction

During the last three decades, advancements in bioprosthetics, biomaterials and tissue engineering have been accompanied by an outbreak in three-dimensional (3D) technology applications in several medical disciplines including plastic, reconstructive and aesthetic surgery. The philosophy behind plastic surgery lies on how basic surgical techniques attempt to close a wound defect and treat congenital anomalies by harvesting, molding (“ πλάσσειν ”) and moving tissues with similar characteristics into the defect area, while maintaining its functionality and aesthetics. The same philosophy embraces the 3D technology principles, which ultimately aim to reproduce with extreme precision anatomical structures and tissues that are absent from the human body, borrowing only a few cells from the body and thus avoiding the creation or limiting the need for donor regions.

Taking one step back, 3D imaging technology is a primary and integral stage in the 3D printing process and has been used for several decades in the preoperative design of many plastic surgery interventions. Burn surgery first introduced the use of 3D tissue printing in plastic surgery; the need for immediate availability of skin substitutes gave birth to the idea of culturing large keratinocyte lines from a smaller number of cells, which were used to cover extensive burn defects in patients lacking available donor areas. Thereafter, improvement in design and extrusion methods made the 3D printing technologies much more affordable, with numerous applications in surgery.

Three-dimensional printing technologies

3D printing is the process by which computer software obtained from 3D imaging is used to guide a machine into manufacturing a detailed 3D model. The process includes fabricating prototypes by laying down sequential layers of material. The different types of 3D printing technologies include selective laser melting, fused deposition modeling (FDM), binder jetting and bioprinting.

In selective laser melting, a laser beam strikes on a fine metal powder bed causing the particles to fuse and join together; then, a roller or blade spreads extra powder onto the build tray and the process is repeated until the form is completed. In FDM, the object is created from a plastic filament or metal wire that is unwound from a coil, melted and deposited in layers. Binder jetting refers to a process where the molding material is applied layer by layer on the build area and the printer head spreads the binder in between to create a solid form. Finally, in bioprinting, successive layers of cells, matrix and nutrients are sprayed from the printer head to create tissue-like 3D structures. Rapid prototyping refers to the technology where objects or models are designed and derived through 3D printing from a computed tomography (CT) scan, magnetic resonance imaging (MRI), or optical scan after a computer-aided 3D modeling stage. Αs these technologies rapidly evolve, 3D printing can provide an individual product in a short period of time, which suits the goal of individualized medicine where each patient is given a specific, tailored, therapeutic approach.

The highly expanding use of 3D printing technologies in various fields of plastic and reconstructive surgery allows the surgeons to create customized patient-tailored products and replace tissues using individualized artificial and biologic implants. Moreover, 3D printing is being increasingly employed in order to improve patients' care and advance surgical training. Recent published data demonstrate promising alternative to current reconstructive surgical treatments, while a huge volume of ongoing research studies on 3D printing applications are being elaborated worldwide.

Areas of biological and surgical applications of 3D printing in plastic surgery include surgical planning and teaching, mandible and maxilla reconstruction after oncological resection, trauma reconstruction, reconstruction of craniofacial congenital anomalies, orthognathic surgery, oculoplastic surgery, breast reconstruction, hand surgery, facial aesthetics and microtia correction, and burns reconstruction.