Nicompartmental Knee Replacement

Posted in Orthopedic Specialties.

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).

Description

A normal knee joint: Some structures have been removed to better show the smooth healthy cartilage lining the joint. The medial, lateral, and patellofemoral compartments are shown with red arrows.

Unicompartmental knee replacement is an option for a small percentage of patients with osteoarthritis of the knee. Your 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.

Disadvantages of Partial Knee Replacement

The disadvantages of partial knee replacement compared with total knee replacement include slightly less predictable pain relief, and the potential need for more surgery. For example, a total knee replacement may be necessary in the future if arthritis develops in the parts of the knee that have not been replaced.

In a partial knee replacement, only the damaged compartment is replaced with an artificial device.

Candidates for Surgery

Your doctor may recommend surgery if you have more advanced osteoarthritis and have exhausted the nonsurgical treatment options. Surgery should only be considered if your knee is significantly affecting the quality of your life and interfering with your normal activities.

In order to be a candidate for this procedure, your arthritis must be limited to one compartment of your knee. Patients with inflammatory arthritis, significant knee stiffness, or ligament damage may not be ideal candidates. Your surgeon will help you determine if this procedure is suited for you. With proper patient selection, modern unicompartmental knee replacements have demonstrated excellent medium- and long-term results in both younger and older patients.

Knee osteoarthritis. (Left) This knee is not a good candidate for partial knee replacement because the arthritis affects both the medial (inner) and lateral (outer) compartments. (Right) In this knee, the arthritis is limited to the lateral compartment. This patient may be a good candidate for a unicompartmental knee replacement.