Replacing a worn-out knee with a plastic and metal one
Knees are the largest joints in our body. The normal knee is made up of the following parts: the lower end of the thighbone (femur), the upper end of the shinbone (tibia), the kneecap (patella), cartilage that covers the ends of the bones, C-shaped wedges called menisci that cushion the joint, and large ligaments that hold the femur and tibia together. The thin, synovial membrane covering the surfaces of the knee releases lubricating fluid to reduce friction of the bones.
As with hip pain, the most common cause of chronic knee pain are three forms of arthritis:
- osteoarthritis that results from age-related wear-and-tear,
- rheumatoid arthritis in which the cushioning, or synovial, membrane in the joint becomes inflamed and thickened, or
- post-injury arthritis that sets in after an injury or fracture.
Depending on the injury or damage, your doctor may recommend either total knee replacement or partial knee replacement. It is possible to have both knees replaced at the same time, if your physician determines that is the best treatment plan for you.
With a total knee replacement, the worn-out surfaces of the knee are resurfaced with metal and plastic components. During total knee replacement surgery, your surgeon will:
- Prepare the bone by removing damaged cartilage surfaces of the femur and tibia and small amounts of the underlying bone
- Replace the removed cartilage and bone with metal components.
- Resurface the patella, if necessary
- Insert a medical-grade plastic spacer between the metal components. This creates a smooth, gliding surface to allow for movement.
Partial knee replacement is a minimally invasive surgical procedure in which the worn, damaged surfaces of the knee joint are resurfaced with metal and plastic components. This can be an option for those whose injury or pain is limited to one area of the knee.
Who is a candidate?
Knee replacement surgery may be considered for those suffering from arthritic knee pain that severely limits the activities of daily living. It is only recommended after careful examination and diagnosis of your particular joint problem, and only after more conservative measures such as exercise, physical therapy and medications have proven ineffective.
What are the risks?
Even though knee replacement surgery is considered a very successful procedure, it is major surgery, and as with any surgery, there are risks you need to be aware of. Possible complications include:
- Blood clots in your leg veins
- Implant loosening
- Nerve or blood vessel damage
- Knee stiffness
How long is the recovery period?
This can vary from person to person, but most people will need to use an ambulation aid such as a walker for four weeks or so. Driving may be possible in four to six weeks, and activities such as golf and bowling can be resumed in as few as 10 to 12 weeks. Some activities such as singles tennis and skiing are not recommended after knee replacement. Most people will be able to go straight home from the hospital, though some patients, particularly those who live alone, may need to spend a few days at a rehab center or nursing home. Keep in mind that healing and recovery times can vary.