Patellofemoral Arthroplasty: An Evolving Science.

Patellofemoral arthroplasty (PFA) has long been a clinical option for patients with isolated patellofemoral arthritis. However, a high rate of failure as a result of patellar instability related to component malposition, soft-tissue imbalance, errant surgical techniques, and poor trochlear implant designs contributed to the underutilization of PFA. The evolution of surgical indications, trochlear implant design, component positioning, and soft-tissue balance has led to improved patellar tracking, fewer failures related to patellar instability, and improved functional outcomes. The development and broad adoption of onlay-style trochlear components, which can be positioned perpendicular to the AP axis of the femur, has substantially improved patellar tracking and, thus, improved the durability of PFA. In addition, favorable data showing success after secondary surgery or revision to total knee arthroplasty after PFA have emerged, which has led to increased use of PFA in appropriately selected patients.