Resection specimen analysis of tibial coverage in total knee arthroplasty.

To maximize tibial coverage during total knee arthroplasty, a study was performed to evaluate the morphology of the proximal tibia at the resection level and assess tibial coverage with respect to existing tibial implants. Unmagnified radiographs of 42 tibial resection specimens were produced and digitized with existing tibial implants from the asymmetrical Genesis and the symmetrical Insall-Burstein II and Press Fit Condylar total knee arthroplasty designs. The average total profile coverage ranged from 80.62% to 84.73%, whereas the average posteromedial coverage ranged from 76.05% to 82.09%. The shape of the tibia at the resection level was asymmetrical, and the overall tibial coverage was never greater than 85%. It appears that the actual shape of the tibial tray and the number of accommodating sizes provide the best ability of a total knee arthroplasty system to maximize tibial coverage, and not simply an asymmetrical or a symmetrical design.