Postoperative patellar maltracking, specifically severe lateral subluxation or tracking issues leading to anterior knee pain, is a highly frustrating complication following total knee arthroplasty. Which of the following technical errors during component implantation is the most devastating and common iatrogenic cause of this specific complication?

Explanation:
The correct option is c. Patellar tracking is exquisitely sensitive to the rotational alignment of the implants. The quadriceps angle (Q-angle) determines the lateral pull vector on the patella. If a surgeon internally rotates the femoral component (rotating the trochlear groove medially) or internally rotates the tibial component (rotating the tibial tubercle laterally relative to the femur), the mechanical Q-angle is drastically increased. This massive lateral vector yanks the patella laterally during flexion, causing it to violently subluxate or tilt off the lateral edge of the trochlea, causing severe pain and rapid polyethylene wear. Reference: Berger RA et al. Malrotation causing patellofemoral complications after total knee arthroplasty. Clin Orthop Relat Res.