Although it is known that there is some asymmetry of the tibial plateau, most total knee arthroplasty designs currently have a symmetric tibial component. Using resection specimen analysis of the tibial plateau from 100 total knee arthroplasty specimens, the authors have examined the tibial plateau to further delineate, quantitatively, the medial and lateral tibial configuration. Unmagnified radiographs of each of the specimens were produced. A line was drawn along the mediolateral axis. The midpoint and points 10, 20, and 30% from the medial and lateral peripheries were then calculated. The average anteroposterior medial 10, 20, and 30% dimensions were 3.79, 4.74, and 5.06 cm, respectively. The average anteroposterior lateral 10, 20, and 30% dimensions were 3.48, 4.10, and 4.16 cm, respectively. The ratios of the lateral/medial anteroposterior distances at 10, 20, and 30% from the periphery were 92.10, 86.77, and 82.46%, respectively. A total knee arthroplasty system that recognizes the difference in the medial and lateral tibial plateaus and designs a prosthesis to account for the smaller, lateral tibial plateau may achieve the goal of maximizing tibial coverage as well as eliminate the problems associated with a symmetric design.