During a posterior-stabilized total knee arthroplasty, you encounter a tight flexion gap and a perfectly balanced extension gap. Which of the following surgical interventions is the most appropriate next step to correct this specific kinematic mismatch?

Explanation:
The correct option is d. This scenario requires a solid understanding of the gap-balancing matrix in total knee arthroplasty (TKA). Because the extension gap is perfectly balanced, any adjustments to the distal femur or the tibia (such as resecting more bone or changing the poly thickness) will disrupt the extension stability. The tightness exists exclusively in flexion. The flexion gap is dictated by the posterior femoral condyles and the proximal tibia. Therefore, decreasing the anteroposterior (AP) size of the femoral component (downsizing) will effectively translate the posterior condylar axis anteriorly, increasing the flexion gap while leaving the distal femoral cut and the perfectly balanced extension gap completely untouched. Reference: Scuderi GR, Tria AJ. Surgical Techniques in Total Knee Arthroplasty.