183. Customizable, Biocompatible And Low-cost 3D Printed Implants For Craniofacial Reconstruction

Abstract

PURPOSE: Craniofacial reconstruction or enhancement requires autologous, cadaveric or alloplastic implants, often requiring intraoperative modification to optimize shape and fit for a particular patient, introducing associated risks of infection, extrusion, expense and donor site morbidity. Given this, there is substantial need for biocompatible, customizable and low-cost facial implants. This study examines the biocompatibility and durability of various polylactic acid (PLA) implant designs +/- decellularized cartilage infill to assess translatability to craniofacial reconstruction. METHODS: Cartilage harvested from ovine ribs was minced or zested and decellularized. Using 3D modeling software, dorsal nasal scaffolds were custom-designed with contours similar to commercially available silicone implants. Scaffolds were printed in polylactic acid (PLA) on a PRUSA i3 MK3S+ printer and implanted subcutaneously on rat dorsa. Two scaffolds were designed as external “cages” of low or high porosity and were without internal supports. These cages were implanted empty or with either minced or zested decellularized cartilage infill, yielding 6 total treatment groups, n=4 each. The remaining two scaffolds had internal PLA filament supports and were implanted without decellularized cartilage infill. Scaffolds were explanted 3 and 6 months after implantation, after which they underwent same-day volumetric analysis via microCT, then Formalin-fixed and embedded in paraffin and sectioned at 10μm for histopathologic analysis. RESULTS: Volumetric analysis of explants at 3 and 6 months revealed retention of implant contours and volume across rebar and minced cartilage-filled scaffolds. Tissue ingrowth between cartilage particles was evident between 3 and 6 months on MicroCT. Empty and zested cartilage-filled cages displayed significant volume loss relative to volume at implant (p < 0.05) with explanted constructs grossly collapsed; intergroup comparison revealed rebar and minced cartilage-filled constructs had superior volume retention relative to empty and zested cartilage-filled cages (p < 0.05). Histopathology with hematoxylin and eosin and safranin-O stains at the 3 versus 6-month timepoints indicated resolving lymphocytic inflammatory response, increased tissue vascularization and improved collagen deposition. CONCLUSION: This study shows that PLA facial implants with sufficient internal supports are a feasible and safe alternative to current craniofacial reconstructive implant options. The biocompatibility of PLA and decellularized cartilage infill promotes ingrowth of healthy tissue with collagen deposition and neovascularization. Further, design and fabrication of these implants can be completed quickly and at minimal cost, allowing for affordable custom-printed implants with a minimal risk profile.