association for study and application of methods of ilizarov

founded in 1989 as asami—north america (the association for the study and application of methods of ilizarov), the limb lengthening and reconstruction society is an organization devoted to stimulating scientific exchange and fostering research and clinical excellence in limb lengthening, limb reconstruction, extremity deformity correction, and complex fracture treatment. 

the ilizarov apparatus is used in orthopedic surgery to lengthen or reshape limb bones; to treat complex and/or open bone fractures; and in cases of infected bones that are not amenable with other techniques.

the device is a specialized form of external fixator, modular in construction. stainless steel rings are fixed to the bone via stainless heavy-gauge wire . the rings are connected to each other with threaded rods attached through adjustable nuts. the circular construction and tensioned wires of the ilizarov apparatus provide far more structural support than the traditional monolateral fixator system. this allows early weightbearing.

the apparatus is based on the principle called "the theory of tensions". through controlled and mechanically applied tension stress, ilizarov was able to show that the bone and soft tissue can be made to regenerate in a reliable and reproducible manner.  the top rings of the ilizarov allow force to be transferred through the external frame, bypassing the fracture site. force is then transferred back to the healthy bone through the bottom ring and the tensioned wires. this allows the ilizarov apparatus to act as a sort of bridge, both immobilizing the fracture site and relieving it of stress, while allowing for the movement of the entire limb and partial weight-bearing. middle rings act to hold the bone fragments in place and to give greater structural support to the apparatus and limb. however, the critical load bearing rings are the top and bottom rings which transfer the force from the healthy bone down to the healthy bone, bypassing the fracture site.

ilizarov is used as external fixation devices on patients to treat non-unions in the 1950s. ilizarov discovered distraction osteogenesis when one patient lengthened his frame rather than compressing it.