The Achilles tendon is the thickest and the longest tendon in the body at about 5 1/2 inches long. It attaches the calf muscle to the bone, but because the tendon has a poor blood supply, it can tear more easily. Sometimes the tears are small.

"A partial tear or micro tear, a lot of people don't know or if they do, its pain, more of the tendinitis, achy, sore," Dr. Larry Fine, orthopedic surgeon, said.

When a tendon ruptures, it’s usually sudden and without much notice because the tendon was weakened by previous tears.

"The theory is that there is a very poor blood supply in that area, so it never heals and one day it goes. It's usually a minor thing, the straw that broke the camel's back."

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