Prolotherapy is the injection of irritants into ligaments and tendons to increase the strength of these tissues. It's used most often with patients who have chronic back pain from injury of the soft tissues.
Even though the treatment has been around for more than a decade, there aren't a lot of studies to show if it works or what's the best treatment protocol. Some doctors combine prolotherapy with other treatment as well.
One group of researchers from Australia reviewed studies published on this treatment method. They only found four studies close enough to be able to compare the results. Most doctors treated patients once a week or once every other week for a total of three to eight treatments.
In some cases patients get good relief from painful symptoms and stop treatment. They may return for further prolotherapy months to years later. More studies are needed to find the answer to your question.