The synovial joint as an “intelligent” friction unit

A concept is advanced and a structural diagram is shown of the synovial joint as an “intelligent” friction unit possessing the properties of a cybernetic system. The joint demonstrates a record-low friction coefficient and compensation of cartilage wear as a triboengineering material maintaining human locomotor activity for many years. It is provided with a feedback system with the sympathetic center controlling the lubricating conditions of the movable joint of the articular bone ends, the lubricating fluid composition, and the elimination of debris from the articular capsule. The main reason why the joint fails is insufficient lubrication due to disruption of the exchange between the bloodstream and the joint synovial shell inducing a deficit of the lubricating synovial fluid. The disruption of the exchange is compensated by injecting synovial fluid substitutes. The paper shows the results of tribological studies and clinical trials providing evidence that the patient’s blood serum can be used as an absolutely compatible lubricating fluid to restore the functions of the articular synovial medium.