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Tennis elbow, or lateral epicondylitis, hurts. It takes a long time to resolve and interferes with daily activities. Here is what causes the problem and what you can do about it.
The tendons in the forearm that insert at the outside (i.e. lateral) part of elbow connect the muscles that enable the wrist and fingers to extend. One tendon, the extensor carpi radialis brevis, is most commonly the bad actor in the story of tennis elbow. While there are different theories about why this tendon, once injured, does not always heal properly, the basic story goes like this:
A tendon is made up of collagen fibers with specialized cells. These cells produce a range of charged molecules, growth factors, signaling factors, and other key components that keep the tissue healthy. The collagen fibers are crosslinked with chemical bridges; these permit the fibers to elongate and then return to the normal length. They provide just the right amount of tension to permit the muscles to act appropriately. And tension is the key to collagen function. Under tension, the collagen appropriately stretches and contracts. Without tension, the collagen degrades.
Tennis elbow can occur with a wide range of activities—not just tennis. A hard hit of the ball, a too-tight grip on the racket or on the handle of an axe, bike bar, rowing machine—a seemingly infinite number of causes—can all cause an overstretching of the tissue. This sudden lengthening may lead to micro- or macro-tears of the crosslinks that bind the fibers together, or even to the fibers themselves.
Then the interesting part begins. With normal activities, these small tears occur all the time. The body responds with increased blood flow. Stem cells migrate to the site of the injury, where specialized repair cells take away the torn fibers and initiate the repair process, laying down new collagen. When done in an orderly fashion, the tissue is restored to normal and no scarring occurs. And when these micro-tears occur in muscle fibers—from weightlifting, for example—the muscle heals with thicker fibers, leading to muscle building.
In the case of tennis elbow, however, something goes wrong. There appears to be not enough stimuli to tell the body to recruit stem cells and initiate the normal healing response. The tearing away from the insertion on the bone at the elbow releases the tension in the fibers just enough to permit the degradation process to run amok. The torn tissue just lies there and slowly degrades. The chemical by-products of this degradation lead to the stimulation of pain neurons. If allowed to continue, cell death and permanent collagen fiber degeneration can occur.
The classic treatment for tennis elbow—cortisone injections —actually makes the problem worse, though it relieves the pain in 50% of the cases. Cortisone inhibits cell metabolism, further shutting down the healing response. But it relieves pain by reducing the inflammatory agents at the site of the injury.
Soft tissue massage to the damaged area breaks down scar tissue and stimulates the production of more collagen through a combination of cell stimulation and collagen fiber cycling. New collagen is laid down at the site of the injury. If careful stress is applied (in the form of gentle exercises); the collagen fibers line up along the lines of stress, leading to healthy healing of the tissue. If the joint is immobilized, however, scarring is more likely to form—with weakened tissue as a result.
Ice can reduce both pain and inflammation in tennis elbow. However, the relief is limited as the issue is not inflammation, but tissue degeneration. It takes a new stimulus to remove this relatively dead tissue. The stimulus can take three forms: surgical, where the tissue is physically removed and sewn back to the proper length; manual, where massage therapy stimulates the repair; or chemical. Chemical stimulation today is best performed by the injection of stem cells and growth factors. These injections change the cellular environment surrounding the degraded tissues. In a recent study comparing the therapeutic results of cortisone injections to growth factors extracted from blood platelets, the growth factors appeared to be more effective. In another study, collagen fibers were restored to their normal mixture of small and large diameter fibrils under the stimulation of amniotic stem cells.
Tennis elbow, if not cured immediately after it appears, has a nasty habit of becoming chronic and painful. Attacking it early and often to prevent the death of the tendon tissue may be the best approach. It is always much easier to cure the injured then resurrect the dead.