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Regional variations in growth plate chondrocyte deformation as predicted by three-dimensional multi-scale simulations.

Gao J, Roan E, Williams JL - PLoS ONE (2015)

Bottom Line: The microscale model predicted that chondrocytes sustained compressive height strains of 12% and 6% in the proliferative and hypertrophic zones, respectively, in the interior regions of the plate.This work provides a new approach to study growth plate behavior under compression and illustrates the need for combining computational and experimental methods to better understand the chondrocyte mechanics in the growth plate cartilage.While the current model is relevant to fast dynamic events, such as heel strike in walking, we believe this approach provides new insight into the mechanical factors that regulate bone growth at the cell level and provides a basis for developing models to help interpret experimental results at varying time scales.

View Article: PubMed Central - PubMed

Affiliation: Departments of Mechanical Engineering, University of Memphis Memphis, Tennessee, 38152, United States of America.

ABSTRACT
The physis, or growth plate, is a complex disc-shaped cartilage structure that is responsible for longitudinal bone growth. In this study, a multi-scale computational approach was undertaken to better understand how physiological loads are experienced by chondrocytes embedded inside chondrons when subjected to moderate strain under instantaneous compressive loading of the growth plate. Models of representative samples of compressed bone/growth-plate/bone from a 0.67 mm thick 4-month old bovine proximal tibial physis were subjected to a prescribed displacement equal to 20% of the growth plate thickness. At the macroscale level, the applied compressive deformation resulted in an overall compressive strain across the proliferative-hypertrophic zone of 17%. The microscale model predicted that chondrocytes sustained compressive height strains of 12% and 6% in the proliferative and hypertrophic zones, respectively, in the interior regions of the plate. This pattern was reversed within the outer 300 μm region at the free surface where cells were compressed by 10% in the proliferative and 26% in the hypertrophic zones, in agreement with experimental observations. This work provides a new approach to study growth plate behavior under compression and illustrates the need for combining computational and experimental methods to better understand the chondrocyte mechanics in the growth plate cartilage. While the current model is relevant to fast dynamic events, such as heel strike in walking, we believe this approach provides new insight into the mechanical factors that regulate bone growth at the cell level and provides a basis for developing models to help interpret experimental results at varying time scales.

No MeSH data available.


Related in: MedlinePlus

Chondrocyte aspect ratio change with deformation at the center and 300 μm away from the edge.Aspect ratio is defined as the ratio of the height over the width of the cells.
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pone.0124862.g009: Chondrocyte aspect ratio change with deformation at the center and 300 μm away from the edge.Aspect ratio is defined as the ratio of the height over the width of the cells.

Mentions: Chondrocytes in the interior of the growth plate experienced less strain (change in cell height) than the macroscopic tissue level strains with peak values of -12% in the center, along the P4 line, and -26% near the growth plate free boundaries (Fig 8). The variation in cellular height strain along the chondrons followed a similar trend to the zonal variation seen at the tissue level. When the chondron was located in the central region of the growth plate, the proliferative chondrocytes attained larger compressive strains (-12%) than hypertrophic chondrocytes (-6%). As was the case for tissue strains, the opposite pattern was seen for chondrons located near the free edges of the growth plate. The change from initial state in the aspect ratio (height/width) of the compressed chondrocytes displayed a similar pattern to that of the height strain. The cells in the hypertrophic zone near the free edge displayed the greatest change reaching a change in aspect ratio of approximately -0.3 (Fig 9).


Regional variations in growth plate chondrocyte deformation as predicted by three-dimensional multi-scale simulations.

Gao J, Roan E, Williams JL - PLoS ONE (2015)

Chondrocyte aspect ratio change with deformation at the center and 300 μm away from the edge.Aspect ratio is defined as the ratio of the height over the width of the cells.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4401775&req=5

pone.0124862.g009: Chondrocyte aspect ratio change with deformation at the center and 300 μm away from the edge.Aspect ratio is defined as the ratio of the height over the width of the cells.
Mentions: Chondrocytes in the interior of the growth plate experienced less strain (change in cell height) than the macroscopic tissue level strains with peak values of -12% in the center, along the P4 line, and -26% near the growth plate free boundaries (Fig 8). The variation in cellular height strain along the chondrons followed a similar trend to the zonal variation seen at the tissue level. When the chondron was located in the central region of the growth plate, the proliferative chondrocytes attained larger compressive strains (-12%) than hypertrophic chondrocytes (-6%). As was the case for tissue strains, the opposite pattern was seen for chondrons located near the free edges of the growth plate. The change from initial state in the aspect ratio (height/width) of the compressed chondrocytes displayed a similar pattern to that of the height strain. The cells in the hypertrophic zone near the free edge displayed the greatest change reaching a change in aspect ratio of approximately -0.3 (Fig 9).

Bottom Line: The microscale model predicted that chondrocytes sustained compressive height strains of 12% and 6% in the proliferative and hypertrophic zones, respectively, in the interior regions of the plate.This work provides a new approach to study growth plate behavior under compression and illustrates the need for combining computational and experimental methods to better understand the chondrocyte mechanics in the growth plate cartilage.While the current model is relevant to fast dynamic events, such as heel strike in walking, we believe this approach provides new insight into the mechanical factors that regulate bone growth at the cell level and provides a basis for developing models to help interpret experimental results at varying time scales.

View Article: PubMed Central - PubMed

Affiliation: Departments of Mechanical Engineering, University of Memphis Memphis, Tennessee, 38152, United States of America.

ABSTRACT
The physis, or growth plate, is a complex disc-shaped cartilage structure that is responsible for longitudinal bone growth. In this study, a multi-scale computational approach was undertaken to better understand how physiological loads are experienced by chondrocytes embedded inside chondrons when subjected to moderate strain under instantaneous compressive loading of the growth plate. Models of representative samples of compressed bone/growth-plate/bone from a 0.67 mm thick 4-month old bovine proximal tibial physis were subjected to a prescribed displacement equal to 20% of the growth plate thickness. At the macroscale level, the applied compressive deformation resulted in an overall compressive strain across the proliferative-hypertrophic zone of 17%. The microscale model predicted that chondrocytes sustained compressive height strains of 12% and 6% in the proliferative and hypertrophic zones, respectively, in the interior regions of the plate. This pattern was reversed within the outer 300 μm region at the free surface where cells were compressed by 10% in the proliferative and 26% in the hypertrophic zones, in agreement with experimental observations. This work provides a new approach to study growth plate behavior under compression and illustrates the need for combining computational and experimental methods to better understand the chondrocyte mechanics in the growth plate cartilage. While the current model is relevant to fast dynamic events, such as heel strike in walking, we believe this approach provides new insight into the mechanical factors that regulate bone growth at the cell level and provides a basis for developing models to help interpret experimental results at varying time scales.

No MeSH data available.


Related in: MedlinePlus