Total Knee Replacement
Total Knee Replacement
by Maria Adams, MS, MPH
Anatomy and Physiology
The knee joint consists of three bony parts: the lower end of the femur, the upper end of the tibia, and the patella. Cartilage between the bones acts as a cushion that absorbs shock and allows the joint to move freely. As the joint moves, the patella glides in a groove along the femur.
Reasons for Procedure
Over time, with normal wear and tear, and sometimes after injury, osteoarthritis can develop in the knee. Osteoarthritis is an inflammation of the joint that occurs due to the breakdown of cartilage.
Symptoms of arthritis or an otherwise damaged knee include: knee pain, usually worsened by weight-bearing activities, restricted range of motion, pops, clicks, or grinding sensations, stiffness, especially in the morning, joint swelling, warmth and/or redness around the knee.
To accurately diagnose your condition, your doctor will conduct a physical exam, and most likely take x-rays of your knee. If the diagnosis is still unclear, your doctor may also order blood tests or perform an MRI scan.
Treatments for arthritis of the knee joint depend on the cause and the severity of the arthritis. The first line of treatment should always consist of non-surgical methods, including: if needed, weight loss to reduce ongoing stress on the joint, physical therapy, or other prescribed exercises that strengthen the muscles supporting the knee joint. a knee stabilizer that supports the joint when the knee is stressed during weight bearing activities.
To relieve pain and inflammation, many people find relief with: pain medications such as acetaminophen, non-steroidal anti-inflammatory medications such as aspirin, ibuprofen, or a prescription brand, corticosteroid injections, which can reduce inflammation, but can weaken the bones if used too often, in addition, dietary supplements, such as glucosamine and/or chondroitin sulfate have been shown to help in some studies.
If non-surgical methods are unsuccessful, a total knee replacement may be considered. A total knee replacement is generally performed when damage to the knee causes so much pain and stiffness that it limits normal activities.
In a total knee replacement, a surgeon replaces the damaged knee joint with an artificial, or prosthetic, joint. A prosthetic knee has three components corresponding to the three bones of the joint: femoral, tibial, and patellar.
During the time leading up to your procedure: If you are overweight, try to lose some weight in order to decrease the amount of stress on your new joint and make the surgery easier to perform. Make home modifications to help smooth your recovery period, such as installing a raised toilet seat, removing throw rugs, and purchasing a firm-back chair that allows the knees to remain lower than the hips. Arrange for temporary help at home once you return from your operation. Consider donating your own blood weeks in advance to be used if a transfusion is required at the time of your surgery.
Also, just prior to your procedure: Arrange for a ride to and from the hospital. The night before, eat a light meal, and do not eat or drink anything after midnight. If you regularly take medications, herbs, or dietary supplements, ask your doctor if and when you need to temporarily discontinue them. Do not start taking any new medications, herbs, or dietary supplements before consulting your doctor. You may be given antibiotics to take before coming to the hospital. You may be given laxatives and/or an enema to help clear your intestines.
Before your procedure, an intravenous line will be started to provide you with fluids, antibiotics, and medications to help you relax.
Total knee replacements may be done under general or spinal anesthesia. Under general anesthesia, you will be kept asleep for the duration of your surgery. A breathing tube will be inserted through your mouth and into your windpipe to help you breathe during the operation.
Under spinal anesthesia, which is now commonly used for this type of operation, you will remain awake but sedated during the procedure. Medication will be instilled in the area of your spinal column to keep the lower half of your body numb. In either method of anesthesia, a catheter will be inserted in your bladder to collect your urine.
Most surgeries take about 2-4 hours. Your surgeon will begin by making an incision across the affected knee.
After moving the patella out of the way, your surgeon will remove damaged cartilage and bone from the ends of the femur and tibia, and the underside of the patella. He or she will then shape the bony surfaces to fit the prosthetic parts.
Next, your surgeon will secure the prosthetic parts in place using bone cement. Traditionally, a metal prosthesis is used on the femur, and plastic on the tibia and patella. But more and more knee replacements are being done using metal on metal, ceramic on ceramic, or ceramic on plastic.
To finish the procedure, your surgeon will close the incision with stitches or staples and leave a drain in the knee to allow extra fluid to flow out. He or she will also place your knee in a splint to make sure it does not move.
Your surgeon may also put your leg in a continuous passive motion device, which mechanically bends and straightens your knee to keep the joint from getting stiff. This device can help speed recovery, and decrease pain, bleeding, and infection.
Risks and Benefits
Possible complications of total knee replacement include: infection in the joint, blood clots in the leg that may travel to the lungs, excessive swelling or bleeding, injury to nearby nerves or blood vessels, adverse reactions to the anesthesia, loosening or dislocation of the prosthesis.
Benefits of a total knee replacement include: returning to the activities you used to enjoy without pain, reducing or eliminating the need for pain medication, resuming regular exercise along with all its health benefits, long life of the prosthesis: usually 10-15 years with typical use.
In a knee replacement, or any other procedure, you and your doctor must carefully weigh the risks and benefits to determine whether it's the most appropriate treatment choice for you.
After the Procedure
After your procedure, your breathing tube will be removed and you will be taken to a recovery area for monitoring. The usual hospital stay is 2-5 days.
While in the hospital: You will be given pain medication. You will continue to receive IV antibiotics and will be given a blood thinner to help prevent blood clots. Depending on the amount of blood lost during your surgery, you may receive a blood transfusion.
Almost immediately after your surgery, you will be encouraged to start moving your new knee. Many patients begin a physical therapy program while in the hospital, which they continue after discharge. Most patients go home once they are able to walk with the aid of a crutch or walker. For some people, a short stay in a rehabilitation unit can help with walking progression and overall recovery.
Once you are home, be sure to contact your doctor if you experience: signs of infection such as fever and chills, increasing redness, swelling, or pain at the site of the surgery, bleeding or discharge from the wound, cough, shortness of breath, or chest pain, blood in the urine or stool, pain, burning, urgency, or frequency of urination, persistent nausea and/or vomiting, pain and/or swelling in your feet, calves, or legs.
- Medical Encyclopedia: Knee joint replacement. Medline Plus. National Institutes of Health. Available at: http://www.nlm.gov/medlineplus/ency/article/002974.htm. Accessed June 14, 2004.
- Total Knee Replacement. Queensland Government. Available at: http://www.health.qld.gov.au/informedconsent/ConsentForms/Ortho/total_knee_arthroplasty.pdf. Accessed June 14, 2004.
- Total Knee Replacement. American Association of Orthopaedic Surgeons. Available at: http://orthoinfo.aaos.org/booklet/thr_report.cfm?thread_id=9&topcategory=knee. Accessed June 30, 2004.
- Total Knee Replacement: A Patient Guide. University of Iowa Department of Orthopedics. Available at: http://www.vh.org/adult/patient/orthopaedics/kneereplacements. Accessed August 11, 2003.
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