Chondrocyte and Pericellular Matrix Deformation and Strain in the Growth Plate Cartilage Reserve Zone Under Compressive Loading

Abstract

Long bones grow by a process in which chondrocytes within growth plate cartilage near the bone ends synthesize and mineralize a cartilaginous matrix that serves as a template for bone cells. The growth plate consists of several distinct zones, including a reserve zone (RZ) that lies between the epiphyseal subchondral bone plate and the proliferative zone (PZ). Mechanical loading of the growth plate modulates chondrocyte activity and bone growth, but the role of RZ in relation to this is unclear. To explore this, an axisymmetric, large deformation model was developed. In this model, chondrocytes were embedded at four different depths within the RZ between the SB and PZ. Growth plate cartilage was partitioned into sections to represent the RZ and the proliferative/hypertrophic zones and zone of provisional calcification (PC). Chondrocytes were surrounded by a layer of pericellular matrix (PCM). By including or excluding the PCM, we could examine the influence of the PCM on stress-strain distributions within and around the chondrocytes. The volume-averaged height, width and principal tensile strains in the cells and PCM varied with the cell depth within the RZ. The presence of the PCM resulted a 10% decrease in cellular hydrostatic pressure and in a 20% increase in the cellular maximum principal strains, except near the SB plate border where cellular maximum principal strains were amplified by 45%. This suggests that the PCM is a component of the cell’s mechanosensory mechanism and acts to reduce intra-cellular pressure while amplifying cellular strains.

Publication Title

Lecture Notes in Computational Vision and Biomechanics

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