 One mechanism is the movement of synovial fluid to allow for better diffusion of nutrients into damaged cartilage, and diffusion of other materials out; such as blood and metabolic waste products.Another mechanism is the prevention of fibrous scar tissue formation in the joint, which tends to decrease the range of motion for a joint.The concept was created by Robert B. Salter M.D in 1970 and, along with help from engineer John Saringer, a device was created in 1978.