Various knee joint implant components are known, some of which can have femoral and/or tibial components equipped with stem(s) to insert into a corresponding intramedullary canal. In such knee systems, stem cross-sectional shapes perpendicular to the length of the stem are known to be generally circular or to have flutes.
On the other hand, the known Quatroloc® femoral total hip component has a generally tapering stem with a rectangular cross-section taken perpendicular generally to its length. It also has stepped shoulders (ridges with sharp distal or leading edges to form cutting steps) along its tapering length. Compare, Whiteside, U.S. Pat. No. 5,755,805.
The knee is a peculiarly created joint, unlike any other in the body. It articulates in numerous ways, and as a result, knee implant replacement joint components may be subject to instability, to include with respect to rotation of any stem in the intramedullary canal of the femur or tibia. As well, various configurations of knee implant replacement joint components may engender instability from inadequate or excessive stress on cortical bone structure, which may weaken, cause necrosis of, or even break the bone, and cause instability. But see, the noted '805 patent to Whiteside, e.g., column 6, lines 14-19, etc.
It would be desirable to ameliorate if not completely solve drawbacks in the art of knee joint replacement implants. It would be desirable to provide the art an alternative.
USPTO Backgrounds
USPTO Backgrounds