Table 1.

Summary of biological changes of aging tendons.

• Yellowish color

• Enlargement of a subpopulation of collagen fibril size and change of fibril size distribution

• Disorganized collagen fibers

• Inconclusive findings on blood flow and vascularity

• Ectopic formation non-tendinous tissues including fat, cartilage and bone tissue

• Decreased cellularity

• Dedifferentiation and senescence of tenocytes

• Reduced proliferation and metabolic activity of tenocyte

• Inconclusive findings on change of collagen and proteoglycan content and composition

• Accumulation of advanced glycation end-products (AGEs)

• Inferior biomechanical properties particularly viscoelasticity