Indications for Patellofemoral Arthroplasty

Patellofemoral arthroplasty (PFA) is the topic of this review article. PFA is the removal and replacement of the patella (knee cap) and the part of the femoral bone it glides over. This operation is used as an intermediary step before a total knee replacement (TKR). It works best for patients with arthritis that just affects the patellofemoral area. If needed, a complete TKR can always be done later.

PFA is not advised for anyone with inflammatory arthritis such as rheumatoid arthritis (RA). Patients who develop post-traumatic osteoarthritis seem to be the best candidates. Patients who have good knee alignment seem to have the best results.

Some alignment problems can be repaired before doing the PFA. For example, a release of tight tissue along the outside edge of the patella may be done. This type of release is advised if the patella is tilted or slightly off the track from where it should be. This helps it return back to the middle over the knee joint where it belongs.

Patients with chondromalacia may not be good candidates for PFA. Chondromalacia is the softening and shredding of the cartilage behind the patella. When PFA is done in the presence of chrondromalacia, there’s a greater chance of ongoing soft tissue pain.

Anyone with a large Q-angle may not benefit from a PFA. The Q-angle is a measure of the angle of the patella tendon as it attaches above and below the patella. Everyone has a Q-angle. Too large of an angle changes the knee biomechanics and represents a precaution to doing a PFA.

The author describes specific techniques to use in the PFA surgery. Postoperative management and clinical results are also reviewed. There are no studies on the best postoperative treatment after PFA. However, there are many studies reporting the outcomes of PFA.

The results have been varied. Some of this variability is linked to the type of implant used. Implant design is improving. There are fewer problems. When problems occur, they are usually caused by soft tissue imbalances or poor position of the implant. These studies are reviewed in detail by the author. Overall, they show that choosing the right patient is the best way to ensure good results.