Which radiographic finding best indicates edge loading in a knee implant?

• A. Unusual wear margins or contact between components
• B. Normal symmetrical wear across the articulating surfaces
• C. Absence of focal wear on radiographs
• D. Decreased joint space with even contact distribution

Answer: (A)

Edge loading pushes the contact to the periphery of the bearing, creating high stresses at the rim. On radiographs, this shows up as unusual wear margins or direct contact between the components at the edge of the articulating surface. That focal, peripheral wear is the clearest sign that the load is being borne at the edge rather than across the central surface, which is why it’s the best indicator of edge loading.

If wear were normal and symmetrical across the surfaces, that would imply even load distribution rather than edge loading. Absence of focal wear on radiographs suggests there’s no edge-specific wear. Decreased joint space with even contact distribution points to other issues, such as generalized joint degeneration, not edge loading.