Where is the most distal point of the femur located and why is it significant to CORI registration?

• A. Location: most posterior point of the femur; Significance: used to determine tidemark.
• B. Location: most distal point of the medial/lateral condyle, typically equal to the intercondylar notch; Significance: CORI places the center of the implant at the most distal point; reference for predicting varus valgus change.
• C. Location: anterior femoral notch; Significance: used to size tibial implant.
• D. Location: tibial plateau; Significance: used to calculate resection depth.

Answer: (B)

The key idea is that in CORI registration the distal femur is anchored by a consistent distal landmark. The most distal point of the femur lies at the ends of the medial and lateral condyles, typically corresponding to the intercondylar notch. This point is used to place the center of the femoral implant during registration. By centering the implant at this most distal point, the system establishes the distal reference for the femur, which in turn sets the coronal alignment and helps predict how the limb may tilt into varus or valgus with different knee positions and resections. In short, this distal landmark provides a reproducible, clinically meaningful reference for accurately positioning the femoral component and anticipating alignment changes. The other described landmarks do not serve this purpose in CORI registration: the posterior point isn’t used for implant centering, the anterior notch isn’t the landmark for sizing the tibial component, and the tibial plateau relates to tibial resections rather than defining the femoral implant center.