Studies using thermal energy to heat the shoulder capsule were first done on animals. There were no obvious problems seen afterwards in relaxation of the tissue. Studies were done next on cadavers (human bodies preserved after death for study) and finally, on live humans. Loss of joint motion hasn't been reported.

If anything there are some concerns that shrinkage alters the elasticity of the tissue. Under too much load there's a risk of stretching out the tissues. In this case, the shoulder can become unstable again with too much motion.

Your best bet for a good result is to follow your doctor's directions and report any problems early on.