The history of what we today know as Extracorporeal Shockwave Therapy or "ESWT" or often just "Shockwave" was actually first discovered in wartime. In the 1940s, during the course of World War II, submarine technology was being used quite extensively and submarine warfare was pretty common. One of the weapons used against submarines was what was called a "depth charge." It was found sometimes, that this weapon would leave submarines intact, yet the people aboard the ships had pretty serious injuries. Most notably, severe lung hemorrhages. It was found that these injuries were caused by incredibly strong sound waves.
So in the 1970s and 80s they decided to try to harness this energy for good and ESWT was born. I should probably mention that "Extracorporeal" means "outside the body" referring to the fact that its non-invasion. However, Shockwave's first uses in medicine (human or veterinary) were not of musculoskeletal origin. Shockwave's first application in medicine was to break up large calcium oxalate stones in the kidney which could not be passed on their own. At this point in time, the only other option for such patients was surgery, so you can imagine how a non-invasive option, called "lithotripsy" in the case of it's use for kidney stones, was welcomed by many (because let's be real, who among us wouldn't go for the non-surgical option every single time, whether for ourselves or for our animals!)
It was noticed, during this time, that patients who were having shockwave treatments for kidney stones were also feeling the affects in other tissues (bone, cartilage, soft-tissue) and that it appeared that Shockwave had both analgesic and healing properties for some of these people. So they started looking at shockwave for musculoskeletal issues.
In the early days, the biggest problem with shockwave as a therapy was that the intensity of the waves was very high in early machines and wasn't particularly adjustable. General anesthesia was used for kidney stone patients, which seems worth it if it meant a chance at avoiding surgery. However, for a therapy, anesthesia adds a whole extra layer to the equation and when looking at it in terms of a cost benefit analysis, the risks of anesthesia often seemed to outweigh the potential gains received from shockwave as a form of therapy.
Thankfully, today's machines have intensity that is significantly more adjustable and anesthesia is not necessary. Therefore, Shockwave has really started to grow in popularity. While more research is being done, the idea is that a powerful acoustic (sound) wave is aimed at a specific, concentrated area, and, in turn, the waves increase cell growth and circulation, which leads to increased healing.
The vet that I work for, uses Shockwave a lot in her practice for both equine and canine patients a like, and has seen a great deal of success in it helping said patients. We tend to use it the most for soft tissue (tendon/ligament) issues, though we certainly have used it for healing in bone and cartilage.
Obviously, its not a be-all-end-all cure, by any sense of any one's imagination, but we've seen some really awesome success. Just something to keep in mind to talk to your vet about should such a need ever arise. It's a really interesting concept and I find the story of how it came to be rather fascinating. Just something I was thinking about because we had an equine shockwave case on Sunday...