Re: Answer # 4. Do check the research but get Joint Active Systems SPS bibliography. Like DSI, EMPI sells dynamic devices and has no research to support efficacy. Most of DSI's recent research is authored by an in-house PhD, not an M.D. and the older stuff consists mostly of case studies i.e no significant patient census, no control, randomization, etc. Both loading techniques (Static Progressive and dynamic) provide results but SPS is documented to work in much less time and has significantly better clinical research backing it up.