Two weeks after total knee arthroplasty, restricted inferior patellar mobility is observed. What is the MOST likely clinical finding?

• A. Diminished active and passive knee flexion
• B. Presence of an extension lag
• C. Increased pain with active knee range of motion
• D. Diminished knee flexion strength

Answer: (A)

Restricted inferior patellar glide limits the patella’s ability to move downward as the knee flexes. This downward motion is necessary for full knee flexion, so when it’s limited, the joint cannot achieve deep flexion. That means both active flexion (muscle-driven) and passive flexion (tester-assisted) are reduced, making diminished active and passive knee flexion the most likely finding two weeks after total knee arthroplasty. Extension lag would point more to quadriceps or extensor mechanism issues, not specifically to patellar glide restriction, and while pain can be present, the hallmark here is the mechanical limitation in flexion.