Well, I figured if you had experience with it, you would know. But anyway:
"Prolotherapy is a simple, natural technique that stimulates the body to repair the painful area when the natural healing process needs a little assistance.That's all the body needs, the rest it can take care of on it's own. In most cases, commonly prescribed anti-inflammatory medications and more drastic measures like surgery and joint replacement may not help, and often hinder or even prevent the healing process. The basic mechanism of Prolotherapy is simple. A substance is injected into the affected ligaments or tendons, which leads to local inflammation. The localized inflammation triggers a wound healing cascade, resulting in the deposition of new collagen, the material that ligaments and tendons are made of. New collagen shrinks as it matures. The shrinking collagen tightens the ligament that was injected and makes it stronger. Prolotherapy has the potential of being 100 percent effective at eliminating and chronic pain due to ligament and tendon weakness, but depends upon the technique of the individual Prolotherapist. The most important aspect is injecting enough of the solution into the injured and weakened area. If this is done, the likelihood of success is excellent."
Now the results vary widely, thus insurance at this point doesn't cover it. Also not very many doctors practice it, and results also depend on the experience of the doctor. Several patients successfully avoided surgery on their spines (for lower back pain , sciatica)by having the cheap and not so dangerous prolotherapy used on them.
Moreover:
"Prolotherapy works by exactly the same process that the human body naturally uses to stimulate the body's healing system, a process called inflammation. The technique involves the injection of a proliferant (a mild irritant solution) that causes an inflammatory response which "turns on" the healing process. The growth of new ligament and tendon tissue is then stimulated. The ligaments and tendons produced after Prolotherapy appear much the same as normal tissues, except that they are thicker, stronger, and contain fibers of varying thickness, testifying to the new and ongoing creation of tissue. The ligament and tendon tissue which forms as a result of Prolotherapy is thicker and stronger than normal tissue, up to 40% stronger in some cases!"