Design of 3D Additively Manufactured Hybrid Structures for Cranioplasty

Abstract

A wide range of materials has been considered to repair cranial defects. In the field of cranioplasty, poly(methyl methacrylate) (PMMA)-based bone cements and modifications through the inclusion of copper doped tricalcium phosphate (Cu-TCP) particles have been already investigated. On the other hand, aliphatic polyesters such as poly(ε-caprolactone) (PCL) and polylactic acid (PLA) have been frequently investigated to make scaffolds for cranial bone regeneration. Accordingly, the aim of the current research was to design and fabricate customized hybrid devices for the repair of large cranial defects integrating the reverse engineering approach with additive manufacturing, The hybrid device consisted of a 3D additive manufactured polyester porous structures infiltrated with PMMA/Cu-TCP (97.5/2.5 w/w) bone cement. Temperature profiles were first evaluated for 3D hybrid devices (PCL/PMMA, PLA/PMMA, PCL/PMMA/Cu-TCP and PLA/PMMA/Cu-TCP). Peak temperatures recorded for hybrid PCL/PMMA and PCL/PMMA/Cu-TCP were significantly lower than those found for the PLA-based ones. Virtual and physical models of customized devices for large cranial defect were developed to assess the feasibility of the proposed technical solutions. A theoretical analysis was preliminarily performed on the entire head model trying to simulate severe impact conditions for people with the customized hybrid device (PCL/PMMA/Cu-TCP) (i.e., a rigid sphere impacting the implant region of the head). Results from finite element analysis (FEA) provided information on the different components of the model.

State-of-Art of Standard and Innovative Materials Used in Cranioplasty

“…It is also a polymer less expensive than other biodegradable polymers such as PLA, PGA and their copolymers [ 51 , 52 , 53 ]. As reported in the literature [ 53 , 54 ], it is a suitable polymer that could be modeled by using computer technology. In particular, as reported by De Santis et al [ 54 ], ink-jet printing (IJP), fused deposition modeling (FDM), laser sintering (LS) and stereolithography (SLA) represent the main additively manufactured (AM) technologies employed for the fabrication of a synthetic structures (biodegradable polymer-based scaffolds) for cranioplasty, with a 3D scan of cranial defects.…”

“…As reported in the literature [ 53 , 54 ], it is a suitable polymer that could be modeled by using computer technology. In particular, as reported by De Santis et al [ 54 ], ink-jet printing (IJP), fused deposition modeling (FDM), laser sintering (LS) and stereolithography (SLA) represent the main additively manufactured (AM) technologies employed for the fabrication of a synthetic structures (biodegradable polymer-based scaffolds) for cranioplasty, with a 3D scan of cranial defects. The technique employed to design the 3D skull and convert it into a 3D virtual model is named reverse engineering (RE) [ 54 ].…”

“…The combination of RE and AM technologies gives the possibility to fabricate and mold the skull part. PCL and PLA and poly(lactic- co -glycolic acid) (PLGA) are the most conventional polyesters manufactured by FDM technology [ 54 ]. In particular PCL is easy to mold due to its lower melting temperature (60 °C) compared to the other polyesters.…”

“…In particular PCL is easy to mold due to its lower melting temperature (60 °C) compared to the other polyesters. An experimental procedure for design and fabricates 3D porous structures using a commercially available 3D printer (Creality3D Ender-3 PRO) on PCL and PLA was reported by De Santis et al [ 54 ]. PCL in combination with PMMA was further studied [ 54 , 55 ].…”

Biomaterials for Soft Tissue Repair and Regeneration: A Focus on Italian Research in the Field

“…Even if exceeding the aim of this review, it is worth to highlight these polymers have been extensively studied for bone regeneration purposes, due to their suitable mechanical properties and the ability to modulate them depending to their blending and copolymerization [201,206,[225][226][227][228]. Bone tissue can undergo serious degenerative problems, i.e., due to accidental nonunion fractures or pathologies such as bone tumors.…”