Anatomic-Based Design, Manufacturing, and Preclinical Assessment of a Novel 3D-Printed Bioscaffold for Total Nasal Reconstruction

Evaluating the Mechanical Strength of 3-Dimensionally Printed Implants in Septorhinoplasty through Finite Element Analysis

BACKGROUND

Autologous nasoseptal cartilage grafts are used to correct nasal asymmetry and deviation in rhinoplasty, but patients who have undergone multiple operations may have limited autologous cartilage tissue available. L-strut implants created on a 3-dimensional (3D) printer may address these challenges in the future, but their mechanical strength is understudied. Silk fibroin-gelatin (SFG), polycaprolactone (PCL), and polylactide (PLA) are bioinks known for their strength. The authors present finite element analysis (FEA) models comparing the mechanical strength of 3D-printed SFG, PCL, and PLA implants with nasoseptal cartilage grafts when autologous or allografts are not available.

METHODS

FEA models compared the stress and deformation responses of 3D-printed solid and scaffold implant replacements to cartilage. To simulate a daily force from overlying soft tissue, a unidirectional load was applied at the "keystone" region given its structural role and compared with native cartilaginous properties.

RESULTS

The 3D-printed solid SFG, PCL, and PLA and scaffold PCL and PLA models demonstrated lower deformations compared with cartilage. Solid SFG balanced strength and flexibility. The maximum stress was below all materials' yield stresses, suggesting that their deformations are unlikely permanent under a daily load.

CONCLUSIONS

The authors' FEA models suggest that 3D-printed L-strut implants carry promising mechanical strength. Solid SFG results mimicked cartilage's mechanical behavior. Thus, scaffold SFG merits further geometric optimization for potential use for cartilage substitution. The 3D-printed septal cartilage replacement implants can potentially enhance surgical management of patients who lack available donor cartilage in select settings.

CLINICAL RELEVANCE STATEMENT

Computational simulations can evaluate the strength of 3D-printed implants and their potential to replace septal cartilage in septorhinoplasty.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Computer-aided designed 3D-printed polymeric scaffolds for personalized reconstruction of maxillary and mandibular defects: a proof-of-concept study

PURPOSE

To investigate the potential reconstruction of complex maxillofacial defects using computer-aided design 3D-printed polymeric scaffolds by defining the production process, simulating the surgical procedure, and explore the feasibility and reproducibility of the whole algorithm.

METHODS

This a preclinical study to investigate feasibility, reproducibility and efficacy of the reconstruction algorithm proposed. It encompassed 3 phases: (1) scaffold production (CAD and 3D-printing in polylactic acid); (2) surgical simulation on cadaver heads (navigation-guided osteotomies and scaffold fixation); (3) assessment of reconstruction (bone and occlusal morphological conformance, symmetry, and mechanical stress tests).

RESULTS

Six cadaver heads were dissected. Six types of defects (3 mandibular and 3 maxillary) with different degree of complexity were tested. In all case the reconstruction algorithm could be successfully completed. Bone morphological conformance was optimal while the occlusal one was slightly higher. Mechanical stress tests were good (mean value, 318.6 and 286.4 N for maxillary and mandibular defects, respectively).

CONCLUSIONS

Our reconstructive algorithm was feasible and reproducible in a preclinical setting. Functional and aesthetic outcomes were satisfactory independently of the complexity of the defect.