|  | | | Rotating Platform Knee | | | 
| Knee joint implants work as a system and consist of femoral, tibial and patellar components. The femoral component is the upper most part of a knee system and is made of a strong polished metal. It covers the end of the thighbone, the femur, as it enters the knee joint. The patellar component replaces the kneecap in the center of the knee. | | The tibial component of the prosthesis covers the top end of the shinbone, (tibia); as it comes into the knee. In a rotating platform knee, the tibia is covered with a metal tray. The tibial component is topped with a disk-shaped polyethylene insert. The polyethylene insert sits on a highly polished surface and rotates around a conical post. | | The insert lies at the point where the femoral and tibial components meet. This subjects the polyethylene to forces generated by the bending and rotation of the knee during activity. Even though the physical and mechanical properties of polyethylene are well suited to this job, wear of the insert can happen. | | Studies have found that in many cases, wearing of the polyethylene in the knee component can cause tiny particles of the material to be grated off and lead to an early failure of the system. The rotating platform implants, such as DePuy's LCS® Complete Total Knee System and p.f.c.® SigmaTM RP Rotating Platform Knee System, are designed to reduce the stresses in the knee which can lead to polyethylene wear and may increase the longevity of the implant. |
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