Where is the most medial point of the tibia located and what is its significance?

• A. Location: intercondylar ridge; Significance: rotation.
• B. Location: tidemark; Significance: planning.
• C. Location: most medial (or lateral) point on the tibial plateau that can be referenced; Significance: sizes the tibial implant (ML distance btw IER and Most Medial Point).
• D. Location: posterior tibial condyle; Significance: measurement.

Answer: (C)

The key idea is how tibial implant size is determined in knee replacement. On the proximal tibia, there is a most medial point on the tibial plateau that can be used as a consistent reference. By measuring the medial–lateral width from that point to a fixed reference (often the inner edge reference, IER), surgeons obtain the ML dimension that guides selecting the tibial component size. This approach uses a stable, reproducible landmark to ensure the implant fits the plateau properly—covering the bone without overhang that could irritate surrounding tissues and helping distribute load evenly across the tibia. Other landmarks mentioned relate to different aspects (rotation on the femur, cartilage boundary, or a posterior edge) and aren’t used for sizing the tibial implant.