Source: Tomorrow's World, BBC TV (UK), 2000-01-19
At Derbyshire Royal Infirmary, UK, doctors are testing a new treatment for ligament injuries like tennis elbow (which is thought to be similar to many cases of coccydynia). The treatment uses high intensity focused ultrasound, similar to a treatment that is given to break up kidney stones. Instead of focusing the sound waves on a kidney stone, they focus them on the damaged tissue. The machine used is called a lithotripter ('stone crusher').
They suggest that tendon and ligament injuries are slow to heal because they have a poor blood supply. The sound waves are perhaps damaging the tissues further, causing new blood vessels to grow into the area and accelerating the rate of healing. Damaging tissue to promote healing is the same idea as that behind prolotherapy.
The surgeon using this treatment says that early results for hand and arm injuries are very promising. A proper trial of the method is under way, and the results will be published.
Note - this is different from the low intensity ultrasound that is often used by physical therapists. That is more like a micro-massage, and doesn't seem to be very successful.