Total Knee Replacement
Total knee replacement, also called knee arthroplasty, is a procedure where damaged bone and cartilage is removed from the knee joint and replaced with a prosthetic implant. There are three main types of knee replacement surgery:
- Total knee replacement replaces the surface of the femur (thigh bone), tibia (shin bone), and patella (knee cap).
- Partial knee replacement replaces only the damaged portion of the knee, while preserving knee ligaments and unaffected cartilage.
- Complex knee revision is used if a knee replacement fails and involves replacing some or all of the parts from the original prosthesis.
Causes of Knee Replacement
The most common cause of chronic knee pain is arthritis. The three main types of arthritis are:
- Osteoarthritis: is a degenerative, “wear-and-tear” type of arthritis, where the cartilage in the knee joint gradually wears away. As the cartilage wears away it becomes frayed and rough, and the protected space between bones decreases causing the bones of the joint to rub more closely against one another.
- Rheumatoid Arthritis: is an autoimmune disease where the immune system attacks its own tissues, damaging normal tissues such as cartilage, ligaments, and bone. Rheumatoid arthritis usually attacks multiple joints and affects the same joint on both sides of the body.
- Post-Traumatic Arthritis: arthritis resulting from a serious knee injury. Fractures to bones around the knee joint or ligament tears can damage articular cartilage, which can over time cause knee pain and limit knee mobility.
The Main Factors Contributing to Osteoarthritis includes:
- Age: arthritis rarely occurs in people younger than 40
- Weight: weight increase pressure on the knee joint. Every pound of weight you gain adds 3 to 4 pounds of extra weight to your knee.
- Heredity: inherited genetic factors can play a role in developing osteoarthritis
- Gender: women ages 55 and older are more likely to develop osteoarthritis of the knee than men
- Repetitive Stress: osteoarthritis of the knee has been linked to occupations that require frequent squatting, kneeling, and lifting weight over 55 lbs.
- Athletics: It is important to note that regular moderate exercise strengthens joints and can decrease the risk of osteoarthritis. However, athletes should take precaution to avoid acute and overuse injuries.
Symptoms affecting the knee as a result of arthritis include:
- Pain that increase with activity, but gets better with rest.
- Swelling and a feeling of warmth in the knee joint.
- Stiffness in the knee, especially in the morning or after you have been sitting for a long period of time.
- Decrease in mobility and range of motion of the knee joint.
- Crackling or grating sensation when the knee joint is in motion.
- Outgrowths of Bone osteoarthritis may cause bony outgrowths called osteophytes, or bone spurs.
Your physician will assess any degenerative changes to the knee joint by conducting a physical exam. During the physical exam, your physician will perform a series of movements to check your muscle strength, range of motion, and joint stability. Your physician will also assess symptoms such as swelling, warmth, or tenderness of the knee joint. X-rays help determine the condition of the knee bones and articular cartilage. Advanced imaging tests, such as a CT scan or MRI, will show images of soft tissue (muscles, ligaments, tendons) within the knee joint.
During knee replacement surgery, an incision is made down the center of the knee to gain access to the joint. The damaged cartilage and underlying bone at the ends of the femur and tibia are removed and metal components are inserted into the knee to recreate the surface of the joint. The patella is also resurfaced with a plastic component. A plastic spacer is then inserted between the metal components to create a smooth gliding surface for the new joint.
Following knee replacement, 90 percent of patients report having less pain, increased range of motion, and a better quality of life. Most patients are able to resume normal activity six weeks after surgery. However, it may take up to six months for pain and swelling to subside. Full recovery from a total knee replacement can range from three months to a year.Physical therapy is extremely important in the outcome of knee replacement surgery. Patients will begin a therapy program immediately following surgery and will continue for six to eight weeks after the replacement. Physical therapy exercises will strengthen the leg muscles, restore range of motion, and help patients resume normal activities as soon as possible after surgery.