What is total knee replacement?
Total knee replacement, also known as total knee arthroplasty, is a surgical reconstruction of the knee joint using prosthetic implants made of special metals, plastic and/or ceramicised metal. Total knee replacement surgery is commonly performed in order to repair a knee joint suffering from damaged cartilage and/or bone, usually as a result of knee arthritis. It can be thought of as a resurfacing procedure of the knee. The damaged cartilage and bone are removed, and the ends of the bones comprising the knee are resurfaced with metal. A plastic insert is placed between the metal components to provide long-lasting, low-friction motion.
Why is total knee replacement performed?
Total knee replacement surgery is generally performed when there is a substantial amount of damage to the cartilage in the knee, and when a patient is suffering from a significant amount of knee pain. The function of the knee is reduced both because of pain and also because of joint damage and deformity.
The surgery may be recommended if a patient is experiencing the following symptoms:
- Severe knee stiffness or pain that is recurring
- Knee pain that lasts throughout the day and night, even when resting
- Knee pain that has not responded well to nonsurgical treatments
- Trouble performing normal activities due to debilitating knee pain
- Knee arthritis that has spread to more than one area of the knee
How do I decide when I need a knee replacement?
Choosing to have a knee replacement surgery is a personal decision that is made together with Dr. McLawhorn. Your preference for surgery, your lifestyle demands, and your expectations for outcomes after surgery aid the decision-making process and will guide your choice between nonsurgical care and knee surgery.
In general, when knee pain begins to interfere with your daily life, prevents you from participating in your recreational activities, wakes you from sleep, and/or requires prescription pain medication, knee replacement surgery is a consideration.
Dr. McLawhorn recommends considering total knee replacement when the following criteria are met:
- Severe bone-on-bone arthritis on an X-ray (not MRI, CT or otherwise), affecting the joint space between the thigh bone (femur) and the shin bone (tibia).
- Severe pain, stiffness and dysfunction of the knee as measured using standardized knee questionnaires (such as the KOOS JR)
- Failure of non-surgical treatments, especially weight loss, physical therapy, and non-steroidal anti-inflammatory medications.
- Knee pain that severely impairs walking and everyday activities.
Furthermore, it is important for the patient to be engaged in his or her recovery. Patients should understand that they are the agents of their own recovery. No one else can recover the knee for them. Recovery will require at least 3 months of personal dedication to daily exercises and intermittent physical therapy sessions (2-3 times per week). Full recovery takes at least 1 year to achieve the full benefits of the knee replacement.
Patients should also understand that knee replacement does not restore a "normal knee". TKR is a mechanical device that has limitations. Patients often experience clicking from the metal and plastic parts. Numbness affecting the skin on the outside of the knee is expected. Kneeling may feel funny or painful, and it is not guaranteed that patients will be able to kneel after TKR. A persistent sensation of stiffness and/or band-like sensation across the front of the knee is common. Mild pain with certain activities is also common. Running and impact activities are discouraged, as these activities will hasten the failure of TKR.
What are the goals for total knee replacement surgery?
First and foremost, the purpose of total knee replacement surgery is to improve pain. Other general goals are:
- Improve knee function
- Provide a stable, well-aligned knee
- Prevent excessive wear of the implanted components
- Avoid complications
How long will a total knee replacement last?
Current data suggests that both hip and knee replacements have an annual failure rate between 0.5-1.0%. This means that if you have your total joint replaced today, you have a 90-95% chance that your joint will last 10 years, and an 80-85% chance that it will last 20 years. With continued improvements in joint implant technology and surgical techniques, these numbers may improve.
What does total knee replacement surgery involve?
A total knee replacement procedure will be customized depending on the individual needs of each patient and the specific steps involved in the surgery may vary from person to person. However, in most cases, you can expect the following:
- Regional anesthesia is provided with either a spinal or epidural to numb your body from the waist down; sedation through an IV will allow you to sleep throughout the surgery
- One or more nerve blocks (injections around sensory nerves) will be given to lessen postoperative pain
- Antibiotics are given prior to surgery to prevent infection
- An incision is made in front of the knee to access the knee joint. The length of the incision is proportional to the depth of the fatty tissue and muscle overlying the knee. It must be long enough to permit full access to the bottom of the thigh bone (femur) and to the top of the shin bone (tibia), so that the prosthetic components can be placed precisely and accurately. Typically an incision that is 5 to 7 inches long is adequate
- The menisci are removed; in most cases the anterior cruciate ligament (ACL) is removed. Depending on the total knee replacement design, the posterior cruciate ligament (PCL) may or may not be removed.
- Damaged cartilage and bone are removed
- The ends of the femur and tibia bones are resurfaced with metal components
- A highly cross-linked polyethylene (plastic) liner is inserted between these components, and a plastic “button” is used to resurface the backside of the patella (kneecap); these provide smooth motion to the joint
- The soft tissues are closed over the implants
What are the advantages of total knee replacement?
There are many benefits to undergoing total knee replacement surgery, including:
- Alleviation of knee pain
- Restoration of mobility in knee
- After appropriate healing time, patients can return to most normal physical activities
What can I expect after total knee replacement?
Immediately after surgery, you will be able to walk on your knee replacement. A walker, crutches or cane may be used for several weeks, if needed. Depending on the demands of your job, you may return to work within 2 weeks of surgery. Return to normal activity, including heavy labor and sports can occur at 6 months after surgery. Full recovery after total knee replacement can take up to 1 year for some patients.
Dr. McLawhorn recommends routine follow-up of all his knee replacement patients. In general, patients will be evaluated at 6 weeks, 12 weeks, 1 year, 2 years, 5 years, and then every 5 years after surgery. A clinical examination and X-rays will be performed at some of these visits.
Learn more about what you can expect before and after surgery in Dr. McLawhorn’s FAQs.
If you are suffering from debilitating knee pain or knee arthritis and exploring total knee replacement as a treatment option, it is important to seek advice from an orthopedic knee specialist to accurately diagnose and treat your condition. Dr. McLawhorn is a hip and knee specialist at Hospital for Special Surgery serving patients in New York and Stamford, Connecticut. To learn more, call 203-705-2113 (CT) / 212-606-1065 (NYC) today or schedule an appointment by using the form on this page.