A
Aseptic loosening of the tibial baseplate
B
Polyethylene wear of the articular surface
C
Patellar maltracking due to internal rotation of the femoral component
D
Fibrous nodule formation in the superior pole of the patella catching in the intercondylar box
Explanation:The correct option is 'd'. 'Patellar clunk syndrome' is highly specific to posterior-stabilized (PS) TKA designs. It is caused by the formation of a fibrous nodule at the superior pole of the patella (quadriceps tendon) that catches in the intercondylar box of the femoral component as the knee actively extends from a flexed position.
Reference: Hozack WJ, et al. The patellar clunk syndrome. A complication of posterior stabilized total knee arthroplasty. Clin Orthop Relat Res. 1989;(241):203-208.