Mechanobiology of mandibular distraction osteogenesis: Finite element analyses with a rat model

Abstract

Three-dimensional finite element (FE) analyses were performed to characterize the local mechanical environment created within the tissue regenerate during mandibular distraction osteogenesis (DO) in a rat model. Finite element models were created from three-dimensional computed tomography image data of rat hemi-mandibles at four different time points during an optimal distraction osteogenesis protocol (i.e., most successful protocol for bone formation): end latency (post-operative day (POD) 5), distraction day 2 (POD 7), distraction day 5 (POD lo), and distraction day 8 (POD 13). A 0.25 mm distraction was simulated and the resulting hydrostatic stresses and maximum principal tensile strains were determined within the tissue regenerate. When compared to previous histological findings, finite element analyses showed that tensile strains up to 13% corresponded to regions of new bone formation and regions of periosteal hydrostatic pressure with magnitudes less than 17 kPa corresponded to locations of cartilage formation. Tensile strains within the center of the gap were much higher, leading us to conclude that tissue damage would occur there if the tissue was not compliant enough to withstand such high strains, and that this damage would trigger formation of new mesenchymal tissue. These data were consistent with histological evidence showing mesenchymal tissue present in the center of the gap throughout distraction. Finite element analyses performed at different time points during distraction were instrumental in determining the changes in hydrostatic stress and tensile strain fields throughout distraction, providing a mechanical environment rationale for the different levels of bone formation in end latency, and distraction day 2, 5, and 8 specimens.

Tissue differentiation and bone regeneration in an osteotomized mandible: a computational analysis of the latency period

“…In addition, the patterns of tissue differentiation predicted by a similar algorithm based on deviatoric strain and fluid velocity were shown to be closest to experimental results compared to other mechano-regulation models [28]. However as other mechano-regulation models have not been investigated here, we cannot comment on their ability to predict tissue differentiation in the osteotomized mandible, and it should be noted that other investigators have related patterns of hydrostatic stress and maximum principal tensile strain to patterns of tissue differentiation during mandibular distraction osteogenesis [35]. Another limitation of the model is that no account is made for rate at which MSCs differentiate.…”

“…Loboa et al [35] used a FE approach to study tissue differentiation at different stages of mandibular distraction osteogenesis in a rat model. By comparing the predicted levels of stresses and strains to histological findings, they showed that tensile strain up 13% in the bone callus corresponded to regions of new bone formation and regions of periosteal hydrostatic pressure with magnitude less than 17 kPa corresponded to locations of cartilage formation.…”

The Influence of Expansion Rates on Mandibular Distraction Osteogenesis: A Computational Analysis

“…Meyer et al 30 demonstrated in a rabbit model of mandibular distraction osteogenesis that cell differentiation, apoptosis and tissue development in the callus were related to applied strain magnitudes. Loboa et al 26,27 carried out a broad study on the mechanobiology of the distraction osteogenesis by using a rat model submitted to hemimandibular osteotomy. They compared histological findings with the strain and pressure fields 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 4 determined using a finite element model and observed that tensile strains up to 13% corresponded to regions of new bone formation and regions of periosteal hydrostatic pressure with magnitudes less than 17KPa corresponded to locations of cartilage formation.…”

Corroboration of mechanobiological simulations of tissue differentiation in an in vivo bone chamber using a lattice‐modeling approach

“…Both models described tissue regeneration in the chamber qualitatively, but more qualitative and quantitative experimental results are necessary to corroborate the predictive capacities of the models. Although these theories predicted some of the main aspects of tissue regeneration in fracture healing, 5,7-9 tissue engineering, 10,11 bone/implant interfaces, 6,12,13 or distraction osteogenesis, [14][15][16][17] they may be criticized for this lack of corroboration.…”