Design Study of Anatomically Shaped Latticed Scaffolds for the Bone Tissue Recovery

Abstract

The current major scaffold design concepts for bone tissue recovery are characterized by labyrinthine design. Their main shortcomings are low level of permeability for new growing tissue, poor design adaptability in regard to particular anatomy and required biomechanical conditions during recovery, as well as very demanding post processing after free form fabrication. In contrast to the most of the existing solutions, latticed scaffold design does not try to imitate the trabecular structure and rejects the labyrinthine concept. It is characterized by simple 3D latticed support structure, which provides a high level of permeability for the new growing tissue cells, and in the same time a proper level of bio-adhesiveness. In addition, its design is easy to manage in order to make it follow the particular anatomical shape and at the same time provide the required elastic properties and structural strength. The paper presents a part of design concept proving process, which is related to stress analysis of the anatomically shaped lattice scaffold design. The aim of the analysis was to identify functional relation between design parameters and elastic properties of the scaffold. The established relations are crucial for getting optimal values of elastic properties of scaffold that are required in a specific trauma-fixation case. The design study shown in the paper was done for the case of lattice scaffold anatomically shaped to the upper part of proximal diaphyseal trauma of rabbit tibia. Design parameters which were altered within the design study were lattice's struts cross-sectional area, density of the struts and angle of the struts intersection. The analysis showed that structural flexibility of latticelike scaffold may easily be changed through modification of three selected design parameters. In this way, it is confirmed that the proposed type of scaffold has an important capability to adapt its elastic properties to the required values, while being able to keep its great permeability and geometrical consistency to the particular anatomy of trauma region.

Holistic Approach in Designing the Personalized Bone Scaffold: The Case of Reconstruction of Large Missing Piece of Mandible Caused by Congenital Anatomic Anomaly

“…The presented study introduced a series of ideas related to the design of personalized bone scaffold whose effects have yet to be explored and evaluated: (1) conceptual design solution of lattice-like (or cage-like) scaffolds that are designed to hold bone graft and do not mimic the geometry of bone tissue, (2) the shape of the cross sections of the struts of the scaffold that provide a better grip of the graft inside the cage of the scaffold and facilitate the penetration of tissue from the outside to the inside of the scaffold, (3) deformable struts whose shape, orientation, and arrangement can be used to control the elasticity of the scaffold in different directions [ 2 , 4 , 6 ], (4) the attachment elements that should be used for attaching the scaffold to the surrounding bone tissue and muscles, (5) design of time-controlled biodegradable scaffold struts, (6) design of bioactive materials that can absorb and disperse bioactive substances in accordance with the external induces (e.g., external custom magnetic field like that reported in [ 1 ], and (7) method of production of integral implants that would enable using relatively cheap FDM process to fabricate the very complex 3D structure of a personalized bone scaffold.…”

“…These two design objectives, hollowness or airiness and closedness (needed to keep the graft within the volume of PBS under the load), are to some extent contradictory. The anatomically shaped cage-like or lattice-like structures of the PBS, where the outward struts are disposed in a bit denser manner than the inner struts, may be considered as an optimal solution [ 2 , 3 ] ( Figure 2 ).…”

“…The PBS should be designed in a way to enable the required magnitude of deformations in the specific directions under the most common load/constraint cases inherent to the patient [ 2 , 4 ]. Actually, properly designed construction and material selection for PBS can provide a suitable strength of the structure that will enable the required magnitude of deformation and fatigue resistance ( Figure 4 ).…”

“…At the same time, it should endure the necessary number of cycles of the load that will be imposed while the recovery process ongoing without losing its support function. There are a few research endeavours reporting on the optimization of lattice-like scaffold structure in terms of mechanical characteristics required for the specific patient [ 2 , 4 ].…”

“… Design parameters that can be used for adjusting the requested deformation [ 2 ]. (b) Initial design.…”