as the articular cartilage component, but is not a good match for the mechanical
properties. The shock absorption, lubrication, and deformation are inadequate and
cause high levels of wear [45]. PVA-C has been studied as a candidate for use as
artificial cartilage tissue due to its high water content, viscoelastic properties, and
porous structure, all contributing to the resemblance to natural articular cartilage
tissue. Furthermore, the natural articular cartilage has been described as possessing
biphasic lubrication qualities, which allow movement of fluid away from the
contact site over a period of loading. This lubrication, which is intrinsic to natural
join tissue, should be mimicked by artificial replacements [93]. According to Oka
et al., the requirements for a good artificial articular cartilage material include good
lubrication, sufficient shock-absorbing ability, good biocompatibility, firm attachment to the bones underneath, and high resistance to wear [94].
It was been shown that under both tension and compression, PVA-C displays
nonlinear mechanical properties and viscoelastic behavior [95]. Additionally,
PVA-C has been observed to have better wear resistance and friction coefficient
than UHMWPE [96, 97].
Oka et al. used PVA dissolved in a mixture of water and DMSO to prepare
PVA-C and study its properties as artificial articular cartilage. They found that the
PVA-C sample allowed a fluid-filled gap, very similar in thickness to the joint space
present in natural articular cartilage, to be maintained between the sample and the
counter-surface under loading. This is beneficial in maintaining proper fluid film
lubrication and weight bearing. In addition, PVA-C displayed a good damping
effect by having a lower peak stress value and maintained it for a longer period of
time under loading [94].
Articular joints are exposed to compressive forces that are applied very quickly,
as well as to very large shear forces. Stammen et al. [53] recognized PVA-C as a
viable option for total joint replacement but only if the load-bearing properties
could be matched with those of natural tissue. Studies of the compressive tangent
modulus and shear tangent modulus were undertaken for the PVA-C product, and a
limited strain-rate dependence under unconfined compression was displayed.
Kobayashi et al. were able to use PVA cryogels as an artificial meniscus in
animal models. The mechanical properties and viscoelastic characteristics as well
as biocompatibility of the material are beneficial for this application. PVA was
processed in a DMSO/water solvent, vacuum dried, and heated for annealing. It was
then left in water, cut and processed into meniscus form, and used as a prosthesis in
rabbits. The samples remained intact for up to 2 years and no fracture or degradation of its mechanical properties occurred. Biocompatibility was also found to be
satisfactory [98].
Swieszkowski et al. studied the use of PVA-C as cartilage replacement for the
shoulder joint. PVA-C was used as the articular layer of the glenoid component.
The mechanical effects of using this material in the glenoid component were
evaluated and a model of the cryogel as a hyperelastic material was developed to
allow design modifications to limit contact stress [96].
To overcome the issues of limited durability and poor adhesion to tissue, Pan
et al. incorporated nano-hydroxyapatite (nano-HA) into the PVA-C matrix
308
W. Wan et al.
properties. The shock absorption, lubrication, and deformation are inadequate and
cause high levels of wear [45]. PVA-C has been studied as a candidate for use as
artificial cartilage tissue due to its high water content, viscoelastic properties, and
porous structure, all contributing to the resemblance to natural articular cartilage
tissue. Furthermore, the natural articular cartilage has been described as possessing
biphasic lubrication qualities, which allow movement of fluid away from the
contact site over a period of loading. This lubrication, which is intrinsic to natural
join tissue, should be mimicked by artificial replacements [93]. According to Oka
et al., the requirements for a good artificial articular cartilage material include good
lubrication, sufficient shock-absorbing ability, good biocompatibility, firm attachment to the bones underneath, and high resistance to wear [94].
It was been shown that under both tension and compression, PVA-C displays
nonlinear mechanical properties and viscoelastic behavior [95]. Additionally,
PVA-C has been observed to have better wear resistance and friction coefficient
than UHMWPE [96, 97].
Oka et al. used PVA dissolved in a mixture of water and DMSO to prepare
PVA-C and study its properties as artificial articular cartilage. They found that the
PVA-C sample allowed a fluid-filled gap, very similar in thickness to the joint space
present in natural articular cartilage, to be maintained between the sample and the
counter-surface under loading. This is beneficial in maintaining proper fluid film
lubrication and weight bearing. In addition, PVA-C displayed a good damping
effect by having a lower peak stress value and maintained it for a longer period of
time under loading [94].
Articular joints are exposed to compressive forces that are applied very quickly,
as well as to very large shear forces. Stammen et al. [53] recognized PVA-C as a
viable option for total joint replacement but only if the load-bearing properties
could be matched with those of natural tissue. Studies of the compressive tangent
modulus and shear tangent modulus were undertaken for the PVA-C product, and a
limited strain-rate dependence under unconfined compression was displayed.
Kobayashi et al. were able to use PVA cryogels as an artificial meniscus in
animal models. The mechanical properties and viscoelastic characteristics as well
as biocompatibility of the material are beneficial for this application. PVA was
processed in a DMSO/water solvent, vacuum dried, and heated for annealing. It was
then left in water, cut and processed into meniscus form, and used as a prosthesis in
rabbits. The samples remained intact for up to 2 years and no fracture or degradation of its mechanical properties occurred. Biocompatibility was also found to be
satisfactory [98].
Swieszkowski et al. studied the use of PVA-C as cartilage replacement for the
shoulder joint. PVA-C was used as the articular layer of the glenoid component.
The mechanical effects of using this material in the glenoid component were
evaluated and a model of the cryogel as a hyperelastic material was developed to
allow design modifications to limit contact stress [96].
To overcome the issues of limited durability and poor adhesion to tissue, Pan
et al. incorporated nano-hydroxyapatite (nano-HA) into the PVA-C matrix
308
W. Wan et al.