Regional differences in mechanical loading may contribute to the spatial pattern of aggrecanolysis in the meniscus.
Interestingly, in PKC-δ KO mice articular cartilage, a mechanical bearing region is more affected than the growth plate, suggesting the mechanical loading might also contribute to the phenotype of PKC-δ KO mice.
A number of factors, such as genetic predisposition, aging, obesity, inflammation, and excessive mechanical loading, are recognized to contribute to OA onset and progression [ 2].
Besides, mechanical loading was found to contribute to the regulation of osteoblast differentiation by regulating the levels of some osteoblast-specific transcription factors, both at the mRNA and protein levels [ 26, 27].
These surface nanostructures may contribute asymmetric resistance under mechanical loading during the flight by increasing the bending and torsional resistance of the wing.
Chondrocytes will additionally respond to biomechanical perturbation such that mechanical loading on normal or diseased tissue will contribute to signalling cascades and upregulate synthetic activity or increase the levels of inflammatory mediators [ 5- 7].
In contrast to humans, no activity restrictions are imposed on the animals and full weight bearing and mechanical loading on the defects could also be contributed to the disintegration of repair tissue.
There is good evidence that mechanical loading conditions that mimic injury and overloading which contribute to altered patterns of load can accelerate mild damage with an early rebuilding phase by increasing MMPs and metabolic activity [ 51- 55].
Age is the most common risk factor for its initiation and progression, with symptomatic OA affecting 10 to 20% of people more than 50 years old [ 2]. 'Wear and tear' injuries due to mechanical loading over many years, genetic polymorphisms and other factors contribute to the development of the disease.
Receptor desensitization and ion channel fatigue are also factors that may contribute to the diminishing response with repeated mechanical loading (Ralevic and Burnstock 1998).
