Table 1.

Aging Changes in Joint Tissues and the Contribution of Aging to the Development of OA.

Aging Change	Contribution to OA
Accumulation of cells exhibiting the senescent secretory phenotype	Increased cytokine and MMP production stimulates matrix degradation
Oxidative stress/damage	Increased susceptibility to cell death and reduced matrix synthesis
Decreased levels of growth factors and decreased growth factor responsiveness	Reduced matrix synthesis and repair
Increased AGE formation	Brittle tissue with increased fatigue failure
Reduced aggrecan size and cartilage hydration and increased collagen cleavage	Reduced resiliency and tensile strength
Increased matrix calcification	Altered mechanical properties and potential activation of inflammatory signaling

MMP=Matrix Metalloproteinases; AGE=Advanced Glycation End-products. Reproduced with permission from Anderson, AS and Loeser, RF, Best Pract. Res. Clin. Rheumatol . 2010; 24:15-26.