What feature of the Legion femur promotes patella tracking?

• A. T Arc
• B. U Line
• C. W Curve
• D. S Curve

Answer: (D)

Patellar tracking is guided by the shape of the femoral trochlea, the groove in which the patella sits as the knee moves. An S-shaped curve in the trochlear groove provides a progressive change in curvature that matches the patella’s path through the full range of flexion and extension. This two-phase curvature helps keep the patella centered, guiding it along the groove and distributing contact forces across the medial and lateral facets. The result is smoother, more stable tracking with less tendency for lateral drift or tilt as the knee bends.

Shapes that are simply flat or have a single-radius path don’t offer the same continuous guidance across the range of motion, so they’re less effective at maintaining consistent patellar tracking. The S-shaped curve, by contrast, aligns with how the patella engages and travels within the groove, making it the best feature for promoting tracking.