Unicompartmental Knee Replacement

WHAT YOU SHOULD KNOW:

• Unicompartmental knee replacement (UKR) is also called unicompartmental arthoplasty. This surgery removes a part of the knee joint that is damaged by osteoarthritis, avascular necrosis, or osteonecrosis. Osteoarthritis is a condition where the joint surface of your knee wears out, causing problems with the cartilage in your knee. Cartilage is the hard tissue at the end of long bones that cushions the bone and decreases friction. Avascular necrosis or osteonecrosis is a condition that occurs when blood flow to certain bones of the body is decreased. The decrease in blood flow causes bones to weaken, leading to breakdown of the joint. These conditions can cause pain, and make it harder for you to move your knee.
  
  
• The knee is made up of three compartments (sections). The middle and lateral sections are formed where the femur bone meets the tibia bone. The third section is where the patella (kneecap) makes contact with the femur. During UKR, surgery is only done on the damaged section of your knee. This section of your knee is replaced with a prosthesis (man-made implant). The implant may be made of plastic, ceramic, or metal. Having UKR may make movements such as walking, sitting, or standing easier, and may decrease your knee pain.

CARE AGREEMENT:

You have the right to help plan your care. Learn about your health condition and how it may be treated. Discuss treatment options with your caregivers to decide what care you want to receive. You always have the right to refuse treatment.

RISKS:

• You may have an allergic reaction to the anesthesia and have trouble breathing. The nerves or tendons around your knee may be damaged during surgery. You may bleed more than expected, or get an infection. You may have problems with your heart. After surgery, your knee may be stiff and painful. Your legs may not be the same length. Your implant may loosen or move out of place. The implant may get worn out over time and need to be replaced. You may need more surgery. After having surgery, you may lose your balance and be more likely to fall for a time.
  
  
• You may get a blood clot in your leg or arm. This can cause pain and swelling, and it can stop blood from flowing where it needs to go in your body. The blood clot can break loose and travel to your lungs or brain. A blood clot in your lungs can cause chest pain and trouble breathing. A blood clot in your brain can cause a stroke. These problems can be life-threatening.
  
  
• If you do not have UKR, you will keep feeling pain with exercise and activity. Over time, your whole knee joint may be worn out. You may feel more pain, and need surgery at a later time. Ask your caregiver any questions that you have about your knee surgery, your medicine, and what to expect after surgery.

WHILE YOU ARE HERE:

Before your surgery:

• Informed consent: A consent form is a legal document that explains the tests, treatments, or procedures that you may need. Informed consent means you understand what will be done and can make decisions about what you want. You give your permission when you sign the consent form. You can have someone sign this form for you if you are not able to sign it. You have the right to understand your medical care in words you know. Before you sign the consent form, understand the risks and benefits of what will be done. Make sure all your questions are answered.
  
  
• IV: An IV (intravenous) is a small tube placed in your vein that is used to give you medicine or liquids.
  
  
• Pre-op care: You may be given medicine right before your procedure or surgery. This medicine may make you feel relaxed and sleepy. You are taken on a stretcher to the room where your procedure or surgery will be done, and then you are moved to a table or bed.
  
  
• Anesthesia: This medicine is given to make you comfortable. You may not feel discomfort, pressure, or pain. An adult will need to drive you home and should stay with you for 24 hours. Ask your caregiver if you can drive or use machinery within 24 hours. Also ask if and when you can drink alcohol or use over-the-counter medicine. You may not want to make important decisions until 24 hours have passed.
  
  
• Foley catheter: This is a tube caregivers put into your bladder to drain your urine into a bag. Keep the bag below your waist. This will help prevent infection and other problems caused by urine flowing back into your bladder. Do not pull on the catheter, because this may cause pain and bleeding, and the catheter could come out. Keep the catheter tubing free of kinks so your urine will flow into the bag. Caregivers will remove the catheter as soon as possible, to help prevent infection.
  
  
• Vital signs: Caregivers will check your blood pressure, heart rate, breathing rate, and temperature. They will also ask about your pain. These vital signs give caregivers information about your current health.

During your surgery:

An incision (cut) is made into the front area of the damaged section of your knee. The damaged ends of your bones are removed using special tools. You may be given a shot of pain medicine into your knee during surgery. Caregivers will put the implant in place. Cement may be used to hold it in place, or it may be fixed in place with screws. A drain (thin rubber tube) may be placed in the area to drain blood and other fluids out of your knee. Your incision is closed with stitches or staples, and a bandage is placed over it.

After your surgery:

The bandage may be changed soon after your surgery to check your wound. X-rays may be done to check the placement of your implant. You will be taken to a room where you can stay until you are fully awake. Do not try to get out of bed until your caregiver says it is OK.

• Cold therapy: The cold from ice placed on your knee causes blood vessels to constrict (get small), which helps decrease swelling, pain, and redness. Ice may be placed on your knee for 15 to 20 minutes every hour. Ice may also be used before you do knee exercises.
  
  
• Compression stockings: Your caregiver may ask you to wear compression stockings. These tight elastic stockings put pressure on your legs after surgery. Wearing pressure stockings helps blood flow through your blood vessels and helps prevent blood clots, also called deep vein thrombosis (DVT).
  
  
• Continuous passive motion machine: You may need to keep your leg in a continuous passive motion (CPM) machine. This machine slowly bends and straightens your leg for you as you lie in bed. You may need to use this machine for three or more hours each day, for ten days after surgery.
  
  
• Deep breathing and coughing: This is an exercise to help decrease your risk for a lung infection after surgery. Do the following:
  
  
  • Hold a pillow tightly against your incision (cut) when you cough to help decrease pain. Take a deep breath and hold it for as long as you can. Deep breathes help open the airways that lead to your lungs. Let the air out and follow with a strong cough. Spit out any mucus you cough up. Repeat the steps 10 times every hour.
    
    
  • You may be given an incentive spirometer to help you take deeper breaths. Put the plastic piece into your mouth and take a very deep breath. Hold your breath as long as you can. Let out your breath and cough. Repeat the steps 10 times every hour.
  
  
• Medicines:
  
  
  • Antibiotics: This medicine is given to help treat or prevent an infection caused by bacteria.
    
    
  • Anti-clotting medicines: This type of medicine is given to help prevent blood clots from forming in your legs. You may be given blood thinners before, during, and after your knee surgery. Medicine may also be given to help clots break apart. This type of medicine makes it easier for you to bleed and bruise. Use a soft toothbrush to help keep your gums from bleeding. If you shave, use an electric shaver.
    
    
  • Antinausea medicine: This medicine may be given to calm your stomach and to help prevent vomiting.
    
    
  • Pain medicines: This medicine is given to decrease pain after surgery. Medicine may be given regularly, or may only be given if you ask caregivers for it. Tell caregivers if your pain does not decrease enough for you to feel better. Do not wait to ask for your pain medicine until the pain is very bad. The medicine may not work as well at controlling your pain if you wait too long to take it. You may have a PCA machine. With this machine, you will be able to press a button and give yourself pain medicine when you need it. Ask your caregiver for help getting out of bed if you feel tired or dizzy. If you take pain medicine before doing physical therapy, you may get through the therapy with less pain.
    
    
  • Non-steroidal anti-inflammatory medicine: This family of medicine is also called NSAIDs. It may help decrease pain and inflammation (swelling). This medicine can increase the risk of bleeding, stomach ulcers or kidney problems in some people. Tell caregivers if you have liver or kidney disease, or a history of bleeding in your stomach.
    
    
  • Muscle relaxers: This medicine helps relax your muscles. It is also given to decrease pain and muscle spasms.
  
  
• Exercise: A physical therapist may help you exercise soon after surgery. Your exercise plan may include stretching your leg muscles and making the muscles stronger. At first you may need to use crutches, a cane, or a walker.

Preventing blood clots:

Around the time of your surgery or procedure you may need to take medicine to thin your blood. Blood thinning medicine helps prevent blood clots from forming in your veins. This medicine makes it easier for a person to bruise and bleed. You will need regular blood tests while taking this medicine. If you have a bleeding disorder or a history of bleeding or blood clots, tell your caregiver. Talk to your caregiver about all of the medicines that you use. Physical activity helps prevent blood clots. Caregivers will help you be as active as possible after your surgery or procedure.

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The above information is an educational aid only. It is not intended as medical advice for individual conditions or treatments. Talk to your doctor, nurse or pharmacist before following any medical regimen to see if it is safe and effective for you.

Learn more about Unicompartmental Knee Replacement (Inpatient Care)