Methods
One hundred knees were scanned by CT in this study and 3D models were created using the volume-rendering technique. Parsons' knob was detected on the axial 3D CT view of the tibial plateau. The location of the knob was presented on a grid aligned with the medial-to-lateral and anterior-to-posterior anatomical tibial axes. All measurements were expressed as a percentage of the corresponding maximum dimension. The width and height of Parsons' knob were also measured.