Knee Replacement Surgery

Osteoarthritis

Osteoarthritis is the most common type of arthritis affecting about 21 million Americans. It tends to develop as people grow older. Osteoarthritis can result from overuse of a joint during sports or work.

The most common reason you may need a partial knee replacement is arthritis (osteoarthritis). Arthritis causes swelling and damage around the padding in the knee (cartilage) , causing it to wear away. As the bones begin to rub against one another, abnormal bone growths, called spurs, can grow around the joint. The bone spurs add to pain and swelling, while disrupting movement.

Osteoarthritis usually happens slowly, and may take years to get bad enough for you to need a partial knee replacement.

Other problems

Some patients may need a partial knee replacement years after an old injury, like a car accident or another type of old injury to the cartilage or ligaments. Patients with rheumatoid arthritis are not candidates for a partial knee replacement because it is a disease of the whole joint and this procedure just treats one area.

Your knee is a hinge joint that joins the thighbone (femur) with the shinbone (tibia). There is a smaller bone that runs beside the shinbone (fibula) and the kneecap at the front of your knee. Surrounding these bones and connecting all around them are strap-like tissues called ligaments that keep the knee steady, connecting the bones to each other, and tendons that attach the muscles to the bones.

• The ACL (anterior cruciate ligament) keeps the shinbone from sliding forward on the thighbone.
• The PCL (posterior cruciate ligament) keeps the shinbone from sliding backward on the thighbone.
• Other ligaments on either side of the knee (medial and lateral collateral ligaments) keep the bones from shifting from side to side.

Where the shinbone and thighbone meets are two cushions made from cartilage (medial and lateral meniscus). Shaped like the letter “C” this cartilage provides shock absorption and keeps the two bones from rubbing together. There are also several sacs inside the joint that provide lubrication for movement. These are called bursae.

Non-surgical treatment

If you are considering a partial knee replacement, you have probably tried non-surgical treatments. If you have not, your doctor will want you to start with those. He or she may suggest losing weight, adjusting your exercise routine, supportive braces, medication or physical therapy. There are injections that can be placed into the knee that can bring relief for weeks or months, allowing you to put off the surgery.

Surgical treatment

Surgical treatment will involve replacing the worn cartilage with metal or plastic replacement parts. To do the surgery, your doctor will replace the area of arthritis with a metal cap and put in a plastic liner. This will let the metal and plastic move smoothly like your old knee should have; and without the arthritis and painful tissue in your knee, you will be able to move and enjoy activities again.

Your doctor will closely examine your X-rays to determine where your arthritis is most severe and decide if you are a good candidate for a partial replacement. If you have very advanced arthritis, you will not be a good candidate for a partial replacement and will need a total knee replacement. Your doctor will help you make the right decision.

There are a few alternatives to a total knee replacement. Some use a combination of procedures to rebuild a knee using donor tissue and stem cells to regrow the articular cartilage. 

The goal of knee replacement surgery is to decrease pain and improve function of the joint. Before you undergo the procedure, Dr. Berry will take your medical history and conduct a physical exam that includes X-rays and MRI to assess the damage to your knee. He will also test the strength of the muscles supporting your knee and how well you can flex the joint.

Depending on the extent of damage inside your knee joint, Dr. Berry may recommend a total or partial knee replacement. Total knee replacement is performed when all three compartments of your joint have arthritis damage. Partial knee replacement, or unicompartmental knee replacement, may be preferred if arthritis is confined to only one area of the knee joint.

The surgery usually takes one to two hours and can be performed in one of two ways. With a traditional open approach, Dr. Berry will make an 8- to 10-inch incision in the front of the knee, remove the damaged part of the joint, and replace it with the artificial implant. If he uses a minimally invasive approach, he will make one or two smaller incisions (four to six inches), resulting in less damage to muscles and tendons.

If you are otherwise healthy, you may qualify to have knee replacement performed as a same-day outpatient procedure without a hospital stay. If performed in the hospital, you may have to stay for at least one to four days. Either way, you can expect to be on your feet within a day with the aid of crutches, a walker, or a cane.
Knee replacement patients can expect a noticeable improvement in flexibility and far less pain within a month. However, exercising your knee is important to reduce swelling and strengthen your muscles, which is why post-operative physical therapy is critical to a successful recovery.

We typically don't recommend knee replacement surgery if you're younger than 50. While recommendations for surgery are based on a patient's pain and disability, most patients who undergo a total knee replacement are typically over the age of 50. 

If your knee replacement surgery isn't done at the appropriate time, total joint replacement can bring your function score up, but not to "normal". 

If a patient waits until he or she can't sleep or is in so much pain, that their mobility is limited, their score typically drops and their post-knee replacement surgery score may only get up to 32. This is way below where we'd like our patients to be.