The goal of knee replacement surgery is to decrease pain and restore function. Although total knee replacement (also called “arthroplasty”) is an excellent option for patients with osteoarthritis of the knee, other surgical options exist.
Patients with osteoarthritis that is limited to just one part of the knee may be candidates for unicompartmental knee replacement (also called a “partial” knee replacement).
Unicompartmental knee replacement is an option for a small percentage of patients with osteoarthritis of the knee.
Your orthopaedic doctor may recommend partial knee replacement if your arthritis is confined to a single part (compartment) of your knee.
Your knee is divided into three major compartments: The medial compartment (the inside part of the knee), the lateral compartment (the outside part), and the patellofemoral compartment (the front of the knee between the kneecap and thighbone).
In a unicompartmental knee replacement, only the damaged compartment is replaced with metal and plastic. The healthy cartilage and bone in the rest of the knee is left alone.
Advantages of Partial Knee Replacement
Multiple studies have shown that modern unicompartmental knee replacement performs very well in the vast majority of patients who are appropriate candidates. The advantages of partial knee replacement over total knee replacement include:
- Quicker recovery
- Less pain after surgery
- Less blood loss
- Also, because the bone, cartilage, and ligaments in the healthy parts of the knee are kept, most patients report that a unicompartmental knee replacement feels more “natural” than a total knee replacement.
- A unicompartmental knee may also bend better.
Partial Knee Replacement
A partial knee replacement operation typically lasts between 1 and 2 hours.
Your surgeon will make an incision at the front of your knee exploring the three compartments of your knee to verify that the cartilage damage is, in fact, limited to one compartment and that your ligaments are intact.
If your surgeon feels that your knee is unsuitable for a partial knee replacement, he or she will instead perform a total knee replacement.
He or she will discuss this contingency plan with you before your operation to make sure that you agree with this strategy.
If your knee is suitable for a partial knee replacement, your surgeon will use special saws to remove the cartilage from the damaged compartment of your knee and will cap the ends of the femur and tibia with metal coverings. The metal components are generally held to the bone with cement. A plastic insert is placed between the two metal components to allow for a smooth gliding surface.