[Arthroplasty of the knee. Postoperative radiologic followup]

The first generation of total knee arthroplasties (TKA) had an unacceptably high failure rate due to prosthetic design problems. The current generation closely duplicates the normal anatomy of the knee. This essay describes the normal imaging appearance. First, evaluation of TKA alignment is important. The center of the knee should lie on the mechanical axis of the leg. The width and location of lucent lines (standard system by the "Knee Society") and the height of the prosthetic joint space must be noted (wear of the polyethylene). On the AP view, the tibial component should be perpendicular in relation to the tibial or up to 2 degrees of varus alignment. On the lateral view, the tibial plateau should be horizontal or should slope downward posteriorly no more than 10 degrees. Many complications of TKA can be detected radiographically (wear, descellement, complications of the patella) and corrected to prevent prosthesis failure.