The type of shock therapy you are referring to is really sound waves (not electrical shock treatments) directed at the calcium deposits. The treatment is called shock wave therapy or extracorporeal shock wave therapy (ECSW).
No one knows for sure how this works but it does seem to bring pain relief and the calcific deposit disappears on X-rays. It appears that the mass is broken up enough by the vibration of the sound waves that the body can then breakdown, liquefy, and absorb or resorb the fragments.
There are several questions still left unanswered about this treatment. Who does it help? Are there some patients for whom this would work better than others? Is it safe and effective for everyone? What dose (pulses per session or number of sessions) gives the best results? Should high- or low- energy be used? Does it even matter?
A recent meta-analysis was conducted by a group of orthopedic surgeons. A meta-analysis is done by reviewing all publications reporting on controlled trials of ECSW for calcific tendinitis of the shoulder.
Some studies compared patients who had ECSW with those who received no therapy, some other type of treatment, or a sham or placebo treatment. Sham or placebo means they thought they were getting the treatment but no sound waves were actually transmitted to the calcium deposits. There were also trials comparing shock wave therapy of different energy levels.
After comparing and analyzing all the data, they found that shock wave therapy was more effective than sham treatments or other therapy such as electrical stimulation. High-energy waves (0.2 mJ/mm2 or higher) worked faster and better in terms of pain reduction and calcium resorption.
Patients experienced a decrease in pain and improved function. And it appears that using high-energy shock waves was more important than the number of sessions. X-rays showed proof that the calcium deposits were disappearing.
It’s still not clear if patient selection is an important factor in the use of ECSW for calcific tendinitis of the shoulder. Future studies are needed to look into this variable as well as define the number of sessions needed for the fastest, most effective treatment of this condition. For now, it’s clear that ECSW is a safe and effective way to treat calcium deposits in the rotator cuff tendons. And it may help patients avoid having surgery.