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

to verify the surgical site.

 

Surgical Procedure

A partial knee replacement operation typically lasts between 1 and 2 hours.

Your surgeon will make an incision at the front of your knee. He or she will then explore 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.

After the surgery you will be taken to the recovery room, where you will be closely monitored by nurses as you recover from the anesthesia. You will then be taken to your hospital room.

 

Complications

As with any surgical procedure, there are risks involved with partial knee replacement. Your surgeon will discuss each of the risks with you and will take specific measures to help avoid potential complications.

Although rare, the most common risks include:

• Blood clots. Blood clots in the leg veins are the most common complication of knee replacement surgery. Blood clots can form in the deep veins of the legs or pelvis after surgery. Blood thinners such as warfarin (Coumadin), low-molecular-weight heparin, aspirin, or other drugs can help prevent this problem.
• You will be given antibiotics before the start of your surgery and these will be continued for about 24 hours afterward to prevent infection.
• Injury to nerves or vessels. Although it rarely happens, nerves or blood vessels may be injured or stretched during the procedure.
• Continued pain.
• Risks of anesthesia

 

Recovery

Because a partial knee replacement is done through a smaller, less invasive incision, hospitalization is shorter, and rehabilitation and return to normal activities is faster.

 

Patients usually experience less postoperative pain, less swelling, and have easier rehabilitation than patients undergoing total knee replacement. In most cases, patients go home 1 to 3 days after the operation.

You will begin putting weight on your knee immediately after surgery. You may need a walker, cane, or crutches for the first several days or weeks until you become comfortable enough to walk without assistance.

A physical therapist will give you exercises to help maintain your range of motion and restore your strength. You will continue to see your orthopedic surgeon for follow-up visits in his or her clinic at regular intervals.

You will most likely resume your regular activities of daily living by 6 weeks after surgery.

Last reviewed: June 2010

AAOS does not endorse any treatments, procedures, products, or physicians referenced herein. This information is provided as an educational service and is not intended to serve as medical advice. Anyone seeking specific orthopedic advice or assistance should consult his or her orthopedic surgeon