In order to understand what a partial knee replacement is, you must first understand the structure of the knee joint. The knee joint is formed by the junction of three bones: the femur (thigh bone), the tibia (shin bone) and the patella (kneecap). These bones are connected to each other by strong ligaments. The powerful muscles of the thigh and calf attach to the bones around the knee by means of tendons. In the healthy knee, these structures work in perfect harmony to move the joint. There are three major compartments in your knee.
The Medial compartment (located on the inner side), the Lateral compartment (located on the outer side), and Anterior (located in the front of the knee between the kneecap and the thigh bone). When two or more compartments of your knee are severely arthritic or damaged, a total knee replacement will completely resurface the ends of the femur, tibia and patella with metallic and plastic implants which are fixed to the bone, generally by acrylic cement. A selected group of patients will present with isolated arthritis on one of the three compartments (generally the inner one) and may benefit from a partial knee replacement, in which only the arthritic, damaged compartment is resurfaced.