Compressive stress‐relaxation behavior of bovine growth plate may be described by the nonlinear biphasic theory

Abstract

The compressive behavior of the bovine distal femoral growth plate was studied in vitro. Strain-rate controlled, compression stress-relaxation experiments were performed on cylindrical bone-growth plate-bone specimens from the interior and periphery of the growth plate. The questions addressed in this study were (a) Can the nonlinear biphasic theory, one with strain-dependent permeability, be used to represent the compressive stress-relaxation behavior of bovine growth plate? (b) How do different assumptions concerning the permeabilities of the chondro-osseous interfaces influence the inferred material properties of the growth plate? and (c) Are there any differences in these properties between the periphery and the interior of the growth plate? Intrinsic biphasic material properties--aggregate modulus (HA), Poisson's ratio (v), and nonlinear strain-dependent permeability coefficients (ko and M)--were calculated from the compression stress-relaxation data with use of a finite element model and a least squares curve-fitting procedure. To verify this constitutive model for the growth plate, an independent set of finite element analyses was performed with use of the determined intrinsic biphasic properties, and comparisons were made between these finite element predictions and two additional sets of experimental data subsequently obtained for the same specimens with use of two slower rates of compression. Excellent agreement was achieved between these finite element predictions and the latter two sets of data. The aggregate modulus was found to be insensitive to the permeability of the chondro-osseous interface. The permeability coefficients were very sensitive to, and the Poisson's ratio was only slightly sensitive to the interface permeability condition. Therefore, the periphery of the growth plate is more compliant and permeable than the interior.

Image Registration Demonstrates the Growth Plate has a Variable Affect on Vertebral Strain

“…This observation of how a growth plate structure will effect the strain experienced by the surrounding bone tissue is supported by investigation of growth plate tissue material properties within rodents, 28 rabbits 8,18 and bovine specimens, 4,5 both in tension, 4,8,28 and compression. 5 Growth plate material properties have been found to vary in the lateral plane, with the interior 5 and the anterior 4 parts of the growth plate found to be the stiffest and strongest. The aggregate modulus of the growth plate has been found to be lower in compression (0.67-1.29 MPa, 5 0.57-1.41 MPa 8 ) than tension (23-48.6 MPa, 4 17.7-27 MPa 8 ), both of which are much lower than the apparent elastic modulus of trabecular bone (67-450 MPa 15 ).…”

Mechanical properties of the porcine growth plate vary with developmental stage

“…Mechanical properties of cartilaginous tissues at various ages have previously been investigated. A comparison between bovine growth plate samples aged 3-4 weeks (Bursac et al 1999), 4 months (Cohen et al 1998), and 12-18 months (Cohen et al 1994) indicates an increase in permeability (k) and a decrease in both the outof-plane Young's moduli (E 3 ) and aggregate moduli (H A ), which are obtained from equilibrium stress relaxation data in unconfined and confined compression, respectively. These trends correlate well with results of the current study and may be explained by a combination of two factors.…”

“…The set of optimal parameters was the combination that provided the lowest value of the root mean square error between user created and resulting optimized curves. The bounds of each property (k 1 , E 1 , ν 21 , ν 31 ) were determined from previous studies providing experimentally and analytically determined results on cartilaginous tissues (Mansour and Mow 1976;Cohen et al 1994Cohen et al , 1998Disilvestro et al 2001;Lu et al 2004;Reynaud and Thomas 2006;Gupta et al 2009;Isaksson et al 2009;Sergerie et al 2009). In addition, the bounds of each parameter had to meet…”

“…In a study by (Cohen et al 1998), reserve zone/chondroepiphysis and proliferative/hypertrophic zone samples from four-month-old bovine growth plates were subjected to unconfined uniaxial compression. The mechanical properties, obtained using the transversely isotropic biphasic elastic model (TIBPE) (Cohen et al 1994), showed that the reserve zone/chondroepiphysis was the least permeable and transverse and axial Young's moduli were approximately twice as large as the other regions of the growth plate. Investigating the three zones separately, Sergerie et al (2009) obtained similar results for the same model with newborn porcine growth plates.…”

Histomorphometric Study of Growth Plate Subjected to Different Mechanical Conditions (Compression, Tension and Neutralization): An Experimental Study in Lambs Mechanical Growth Plate Behavior

“…Static load inhibits physeal growth whereas cyclic loads can stimulate the growth of the physeal cartilage in rat metatarsals, and the growth plate morphology follows the contours of principal tension stresses and minimum shear stresses (6). A reduction in compression is also known to cause accelerated growth (11,19,24).…”