Calcium is a mineral that makes up a large portion of the structure and ‘hardness’ of bones. However, softer tissue like muscles and tendons can develop deposits of calcium mineral in a process called calcification. The important Achilles tendon is equally at risk for developing calcification as any other tendon or muscle, and perhaps more so due to its strength and the way it pulls on the heel to bring the foot downward. This process can start simply due to increased traction on the tendon’s attachment on the heel bone when it is tight, or due to injury to its fibers. The damaged tissue can eventually host calcium deposits which can be seen on x-rays. To be clear, this calcification process is not the formation of bone, but rather small groups of calcium that are solid enough to appear on x-rays. They appear as fluffy white patches small and large across the back of the heel away from the heel bone. These calcifications can even look like a fractured bone spur if they are grouped close to the heel bone, sometimes leading to misdiagnosis.
The calcifications themselves are not generally a source of pain in the Achilles tendon and heel, but are usually the result of the damage and inflammatory process that creates the original pain. These calcifications are generally the result of long term tendon damage, and represent a chronic process that began before the calcifications appeared. However, if a new acute injury occurs to the Achilles tendon after calcification begins, it is possible the freshly injured tendon fibers can be even more irritated by the surrounding calcified tissue.
Unfortunately, there is no way currently to destroy or effectively break up the calcified tissue when it is spread diffusely, and attempts to surgically remove it may lead to further Achilles tendon damage and inflammation. Smaller areas of calcification can be cut out though, and special graft tissue can be used to reinforce the tendon to help reduce the chance of weakening following such surgery.