Patellofemoral arthroplasty: the third compartment.

Isolated arthritis on the patellofemoral articulation has received minimal attention in the past. It is now recognized to be relatively common, especially in women. Treatment alternatives such as patellectomy, unloading osteotomies, debridement, and cartilage transplant have not offered long-term sustainable benefits. Therefore, there is a need for a reliable patellofemoral arthroplasty. The current indications for surgery include middle-aged patients with isolated patellofemoral arthritis without severe maltracking, inflammatory arthritis, crystalline arthropathy, femorotibial arthritis, or high demands. Reports show 60% to 80% good-to-excellent results in the short term and midterm. The main problems with patellofemoral arthroplasty have been patellar instability and patellar edge loading on the condylar cartilage in flexion. Newer designs are addressing both issues and are leading to improved results.