ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

properties as well as protect the hydrogel-scaffold interface from the lateral expansion
of the host cartilage following the implantation of an osteochondral construct. The
displacement during compression in the osteochondral defect treatment model (data not
presented) shows the lateral expansion of the host cartilage against the construct. The
teZCC helps absorbing the stress from the lateral compression and stiffened the
interface. A stiffer hydrogel could probably be used to further constrict the lateral
expansion of the surrounding cartilage but the hydrogel’s anchorage with the underlying
scaffold will still need to be enhanced.
Finally, no major effect of the teZCC thickness on the shear stress was observed. This
enables us to work with a thinner zone, which would better mimic the zonal architecture
of the host tissue and help lateral interaction and integration.
Based on the values of push-off tests obtained from the in vitro engineering of the ZCC,
an increase of the maximum shear stress to failure can be obtained at the interfaces. The
maximum shear stress the construct could sustain shows that without the teZCC, it
would not be possible to avoid delamination in the simulated osteochondral defect
treatment. Altogether, this suggests that biochemical surrogates could be used to
enhance functional properties and calcification of a region similar to a zone of calcified
cartilage.
6. REFERENCES
[1] Oegema T, Jr., Carpenter R, Hofmeister F, Thompson RC, Jr. The interaction of the zone of
calcified cartilage and subchondral bone in osteoarthritis. Microsc Res Tech 1997;37:324-32.
[2] Hauch KN, Oyen ML, Odegard GM, Haut Donahue TL. Nanoindentation of the insertional
zones of human meniscal attachments into underlying bone. J Mech Behav Biomed Mater
2009;2:339-47.
[3] Ferguson VL, Bushby AJ, Boyde A. Nanomechanical properties and mineral concentration
in articular calcified cartilage and subchondral bone. J Anat 2003;203:191-202.
[4] Broom ND, Oloyede A, Flachsmann R, Hows M. Dynamic fracture characteristics of the
osteochondral junction undergoing shear deformation. Med Eng Phys 1996;18:396-404.
[5] Allan KS, Pilliar RM, Wang J, Grynpas MD, Kandel RA. Formation of biphasic constructs
containing cartilage with a calcified zone interface. Tissue Eng 2007;13:167-77.
[6] Hollenstein J, Hwang J, Cory E, Pioletti DP, Sah RL. Engineering a zone of calcification
that is localized in space and mechanically stiff. Trans Orthop Res Soc. Long Beach, CA2011.
p. 1895.
[7] Mathieu LM, Mueller TL, Bourban PE, Pioletti DP, Muller R, Manson JA. Architecture and
properties of anisotropic polymer composite scaffolds for bone tissue engineering. Biomaterials
2006;27:905-16.
[8] D' Lima DD, Chen PC, Colwell CW. Osteochondral grafting: effect of graft alignment,
material properties, and articular geometry. The open orthopaedics journal 2009;3:61-8.
[9] Athanasiou KA, Rosenwasser MP, Buckwalter JA, Malinin TI, Mow VC. Interspecies
comparisons of in situ intrinsic mechanical properties of distal femoral cartilage. J Orthop Res
1991;9:330-40.
[10] Mente PL, Lewis JL. Elastic modulus of calcified cartilage is an order of magnitude less
than that of subchondral bone. J Orthop Res 1994;12:637-47.
[11] Tze WTY, Wang S, Rials TG, Pharr GM, Kelley SS. Nanoindentation of wood cell walls:
Continuous stiffness and hardness measurements. Compos Part a-Appl S 2007;38:945-53.
[12] Boskey AL. Hydroxyapatite formation in a dynamic collagen gel system: effects of type I
collagen, lipids, and proteoglycans. J Phys Chem 1989;93:1628-33.
[13] Muller-Gerbl M, Schulte E, Putz R. The thickness of the calcified layer of articular
cartilage: a function of the load supported? J Anat 1987;154:103-11.