Arthritis: Knee Replacement Surgery

Who Needs Knee Replacement Surgery?

A person may want to consider knee replacement surgery if they have a stiff, painful knee that prevents them from performing even the simplest of activities and other treatments are no longer working.

What Happens During Knee Joint Replacement Surgery?

Once you are under general anesthesia (meaning you are temporarily put to sleep), spinal, or epidural (numb below the waist) anesthesia, an eight- to twelve-inch cut is made in the front of the knee. The damaged part of the joint is removed from the surface of the bones, and the surfaces are then shaped to hold a metal or plastic artificial joint. The artificial joint is attached to the thigh bone, shin and knee cap either with cement or a special material. When fit together, the attached artificial parts form the joint, relying on the surrounding muscles and ligaments for support and function.

What Are Recent Advances in Knee Joint Replacement Surgery?

Minimally invasive surgery (MIS) has revolutionized knee replacement surgery as well as many fields of medicine. Its key characteristic is that it uses specialized techniques and instrumentation to enable the surgeon to perform major surgery without a large incision.

MIS knee joint replacement requires a much smaller incision, three to five inches, versus the standard approach and incision, which is typically eight to twelve inches. The smaller, less invasive approaches result in less tissue trauma by allowing the surgeon to work between the fibers of the quadriceps muscles instead of requiring an incision through the tendon. It may lead to less pain, decreased recovery time and better motion due to less scar tissue formation.

Currently this less invasive procedure is performed by only a small percentage of orthopaedic surgeons in North America. Because this type of surgery is still relatively new, research has been initiated to determine how the immediate and long-term results will compare to traditional surgery.

What Happens After the Surgery?

The average hospital stay after knee joint replacement is usually three to five days. The vast majority of people who undergo knee joint replacement surgery have dramatic improvement. This improvement is most notable one month or more after surgery. The pain caused by the damaged joint is relieved when the new gliding surface is constructed during surgery.

After knee joint replacement, people are standing and moving the joint the day after surgery. At first, you may walk with the help of parallel bars, and then a walking device -- such as crutches, walker, or cane -- will be used until your knee is able to support your full body weight. After about 6 weeks, most people are walking comfortably with minimal assistance. Once muscle strength is restored with physical therapy, people who have had knee joint replacement surgery can enjoy most activities (except running and jumping).

How Long Will I Need Physical Therapy After Knee Joint Replacement?

After you are discharged from the hospital, you are usually sent home or to a rehabilitation facility, depending on your condition at that time. If you are sent to a facility, the average rehabilitation stay is approximately seven to ten days. If you are sent directly home from the hospital, your doctor will usually have a physical therapist come to treat you at home. Your doctor also may have you go to an outpatient physical therapy facility as the final stage of the rehabilitation process. Outpatient therapy may last from one to two months, depending on your progress.

Remember, every person is different and the course of rehabilitation will be determined on an individual basis with the assistance of your doctor and physical therapist.

Will I Have to Avoid Certain Movements and/or Activities Following Surgery?

After knee joint replacement surgery, you should not pivot or twist on the involved leg for at least six weeks. Also during this time, when lying in bed, you should keep the involved knee as straight as possible. Kneeling and squatting also should be avoided soon after knee joint replacement surgery.

Your physical therapist will provide you with techniques and adaptive equipment that will help you follow guidelines and precautions while performing daily activities. Remember, not following the given precautions could result in the dislocation of your newly replaced joint.

How Can I Manage at Home During Recovery?

The following tips should make your recovery at home easier.

• Stair climbing should be kept to a minimum. Make the necessary arrangements so that you will only have to go up and down the steps once or twice a day. 
• A firm, straight-back chair is extremely helpful in adhering to these joint precautions. Recliners should not be used. 
• To help avoid falls, all throw rugs should be removed from the floor and rooms should be kept free of unnecessary debris. 
• Enthusiastic pets should be kept far away until you have healed. 

You should ask your doctor before returning to such activities as driving, sexual activity, and exercise.

Is Knee Joint Replacement Surgery Safe?

Knee joint replacements have been performed for years and surgical techniques are being improved all the time. As with all surgeries, however, there are risks. Since you will not be able to move around much at first, blood clots are a particular concern. Your doctor will give you blood thinners to help prevent this.

Infection and bleeding also are possible, as are the risks associated with using general anesthesia. Other less common concerns that you and your doctor must watch out for include the following:

• Pieces of fat in the bone marrow may become loose, enter the bloodstream and get into the lungs, which can cause very serious breathing problems. 
• Nerves in the knee area may be injured from swelling or pressure and can cause some numbness. 
• Other bones may be broken during the surgery, which may require a longer hospital stay. 
• The replacement parts may become loose or break. 

How Long Will My New Joint Last?

When joint replacement procedures were first performed in the early 1970s, it was thought that the average artificial joint would last approximately 10 years. We now know that about 85 percent of the joint implants will last 20 years. Improvements in surgical technique and artificial joint materials should make these artificial joints last even longer.