A knee arthroplasty replacing all three compartments of the knee joint (medial and lateral compartment of the tibiofemoral joint, and the patellofemoral compartment). Current practice in knee arthroplasty in Germany rarely includes patellar resurfacing. Strictly speaking, these cases should therefore not be classified as total knee arthroplasties, but rather as bicompartmental arthroplasties. However, the term “total knee arthroplasty” for bicompartmental knee arthroplasties is used widely in Germany.