Does inversion therapy work? It all depends on your description of "work". Inversion therapy platforms similar to the Teeter EP550 inversion table affect the spinal joints and, to some extent, other joints by reversing the pull of gravity. The concept is that the never ending effect of gravity pushing down on our spines and bodies every day has a negative effect on the health of our spine and joints and may even promote degenerative changes in the vertebra that could lead to a pinched sciatic nerve, sciatica, or low back pain in general.
Gravity is of course needed to survive on earth and even has a benficial effect on healthy persons . The space program has reams of findings on the deleterious effects of weightlessness (no gravity) on astronauts. Without gravity, muscles become weak and bones begin to lose strength and mineralization making them more apt to break . So some exposure to gravity is indeed neccessary . The negative part of gravity is the eternal compression from our heads pulling down toward the earth. For the perfect specimen who is optimally muscled and has a perfectly aligned spine , gravity and the compression it causes will, most likely , not have any negative effect. The problem is that most of us are not anywhere near the physical shape of the " ideal person " and we do feel the effects of gravity.
Inversion therapy has been available for years . Recall the gravity boots from 30 or forty years ago? You had to be very agile just to get them hooked on the bar and you had better hope the bar was durable or you would wind up on your head! The next model was less difficult to use but expensive and bulky making residential use quite impractical. These models kept the consumer by the thighs in which was recognized as a 90-90 position. The user was bent forward at the hips or waistline 90 degrees and secured by their knees being flexed 90 degrees as well. These devices did the job quite nicely except for the reality that considerable strength or agility was required to achieve to an upright position. For a person struggling from a high level of pain, it could be very difficult to get out of the device without further straining their back.