Surgery is normally used if other treatments, such as medicine and physical therapy, haven't helped relieve pain and stiffness.
Surgery involves removing the damaged cartilage and bone and implanting an artificial joint made from metal, plastic, and other synthetic materials.
According to the American Association of Orthopedic Surgeons (AAOS), over 90 percent of people who have a total knee replacement will have significantly less pain after the operation and a greater ability to move around and carry out daily tasks.
Any surgical procedure carries risks, ranging from infection and pain to blood clots. However, the AAOS points out that over 600,000 procedures take place each year in the United States, and fewer than 2 percent result in serious complications.
There are many different risks that come with knee replacement surgery. Some risks are linked to surgery while others are linked to how the body reacts to the operation.
Before surgery, patients are given anesthesia so that there won't be any pain. Under general anesthesia, the patient will be unconscious and unresponsive to pain.
Anesthesia can cause a number of side effects, including nausea, headaches, and allergic reactions.
Alternatively, spinal anesthesia only numbs the leg or lower body, and the patient remains awake during surgery.
General anesthesia can cause side effects such as:
- Sore throat (due to the use of a breathing tube during surgery)
- Heart attack or stroke (rarely)
Patients are more likely to have complications from general anesthesia if they have existing heart disease, lung problems, or other serious medical conditions.
Spinal anesthesia causes fewer serious side effects than general anesthesia. Individuals are less likely to feel drowsy after surgery, and the risk of blood loss, clots, heart attack, and stroke are reduced.
Side effects from spinal anesthesia can include:
- Trouble urinating
- Allergic reactions
- Nerve injury from the needle used to administer the anesthesia (rarely)
Any opening in the skin can allow bacteria to enter, which could potentially lead to an infection. The surgeon will take precautions to prevent infection during surgery.
Once the patient returns home, they should watch for the following signs of infection:
- Discharge from the surgical site
- Fever and chills
If an infection does arise, the doctor will prescribe antibiotics to treat it.
It's normal to bleed during and after surgery. In rare cases, a person may lose too much blood during the procedure and need a transfusion.
Sometimes, after surgery, blood can pool under the skin and cause it to swell. If that happens, another procedure may be needed to release the blood.
Blood clots are one of the biggest risks from knee replacement surgery. If a blood vessel is damaged or the patient is immobile for several days after surgery, blood flow can slow, and a blood clot can form.
A blood clot in one of the deep veins in the legs is called deep vein thrombosis (DVT). If the clot breaks free, it can travel to the lungs and block blood flow. This is called pulmonary embolism, and can be life threatening. Moving the legs and wearing compression devices after surgery can prevent clots from forming.
Pain and swelling
Pain and swelling are common after surgery, but the severity of these symptoms will vary from person to person. Pain relievers are typically prescribed to help manage any discomfort following surgery. These medications are typically only used for a short period of time, but in cases where pain continues for a few months after surgery, other treatments may be prescribed.
There may be swelling in the knee, ankle, and foot after surgery. Icing the affected area and light exercise can help to bring swelling down.
Surgery involving general anesthesia can lead to breathing problems with some patients.
Some people have trouble breathing deeply right after surgery, especially if they had general anesthesia.
If too little air reaches the lungs, mucus can build up inside of them and lead to pneumonia.
A nurse will help the patient take deep breaths to get the lungs working normally again.
Nerve and artery damage
In rare cases, the surgeon cuts a nerve or blood vessel that runs close to the knee. If this happens, a second surgery might be necessary to repair the damage. A cut nerve can cause a loss of feeling or movement - sometimes permanently - in the affected area.
Rarely, people can have an allergic reaction to the metal components used in knee implants. In some people with metal allergies, implant parts trigger a reaction that produces symptoms that include swelling, a rash, and blisters.
In rare cases, allergic reactions can cause body-wide symptoms like weakness, diarrhea, headache, and loss of function in the implant area. Individuals who have had skin reactions to metal jewelry in the past should ask the doctor if a test for metal allergies is necessary before surgery.
Joint replacement technology has improved a lot over the years, but it's not perfect. A new joint can loosen, wear out, or lose its stability. If the joint fails, the patient is likely to experience continued pain and stiffness after the surgery, and another procedure might be needed to replace it.
Reducing the risks
The best way for a patient to ensure a positive outcome is to follow the surgeon's instructions. If there are any questions about caring for the new knee, the individual should ask the doctor.
Here are a few tips to help prevent or reduce common knee replacement complications:
- Take it slow: resting for a few days after surgery is essential. It can take 3 to 6 weeks before getting back to normal levels of activity, including climbing stairs and driving.
- Exercise: it is important to get out of bed and move around. Doing the exercises as recommended by the doctor will help regain movement in the knee. Staying active will also lower the risk of a blood clot.
- Use ice: holding ice on the knee can bring down swelling and reduce pain in the first few days after surgery. Propping the knee up on a couple of pillows can also help with swelling.
- Pain relief: the surgeon will prescribe medicine to relieve any pain following surgery. Managing pain can help the patient stay active, which will speed up recovery.
- Compression devices: the doctor will recommend that compression stockings are worn, or a boot-like device that continually applies pressure to the leg. These devices prevent blood from pooling in the legs and forming a blood clot.
- Clean the wound: the surgeon will give instructions on caring for the wound. Keeping the area clean can help prevent infection.
Patients should look at alternative treatment options such as knee injections before choosing surgery.
Before deciding on knee replacement surgery, other noninvasive treatments will be used to relieve osteoarthritis pain and stiffness:
- Devices like shoe orthotics, a cane, or a walker
- Exercise and physical therapy
- Pain relievers such as acetaminophen (Tylenol), or NSAIDs like ibuprofen (Motrin), naproxen (Naprosyn), and celecoxib (Celebrex)
- Steroid or hyaluronic acid injections into the knee
- Weight loss
Questions to ask
To ensure the best possible outcome from the surgery, and reduce the risk of complications, patients should ask the doctor these questions before the procedure:
- What kind of outcome can I expect? How will knee replacement surgery help me?
- Do I have any other options besides surgery to relieve pain and stiffness?
- What can I do to prepare before surgery to improve my odds of success?
- What are the possible risks of having knee replacement surgery?
- What can I do to lower my risk for complications?
- What are the signs that I'm having a complication?
- When should I call you?
Knee replacement surgery is a relatively common procedure that improves mobility and the quality of life for many people. Fewer than 2 in every 100 people will experience a serious complication, usually relating to an existing health condition. It is important to discuss all options first with your doctor.