Patellofemoral Pain After Total Knee Arthroplasty.

The incidence of patellofemoral complications after total knee arthroplasty has been reported to range from 2% to 7%. Such complications include pain, sub-luxation, dislocation, loosening, and wear. Usually these complications are attrib-utable to prosthetic design or surgical technique. Today, it is understood that patellofemoral prostheses must have a degree of congruence; must allow smooth, not abrupt, motion; and must restore a relatively normal size relationship between the patella and the femur. Surgical technique requires strict attention to (1) restoration of the patellofemoral spacing while avoiding "overstuffing" of the patellofemoral compartment; (2) accurate superior and medial positioning of the patellar component; (3) restoration of the rotational alignment of the femoral and tibial components; and (4) appropriate balancing of the patellofemoral soft tissues.