There are both short- and long-term complications that can arise from a total knee replacement. All surgeries carry the risk of anesthetic mishaps and excessive bleeding. There is also a small (less than 3 percent) risk of infection immediately after the surgery. Antibiotics are routinely given to patients in the first day after the surgery to lessen the risk. However, infection remains a risk long after the surgery has been performed. If the infection can't be controlled, the implant will have to be removed and replaced.
Of course, one serious long-term complication is that the implant itself will deteriorate with time, especially if its bearer is physically active. Although there are lifestyle choices that can extend the life of the implant, such as weight loss and avoidance of high-impact activities, the implant is still going to wear out eventually, especially if the recipient is middle-aged or even younger.
Since so many operations are performed each year, most facilities that offer the surgery aren't only skilled at their craft, but well practiced. However, it's not rare for a replacement knee to be inserted with an alignment that leads to increased wear and strain on the implant, leading to discomfort or a dislocation of the artificial joint.
The patella, which is moved aside during the procedure, may suffer from instability or tissue unevenness, or come into contact with the device, causing discomfort.
Most joint failures will be caused by the implant loosening from the bones. This is caused by degeneration of the bone tissue. The joint is lined by a thin layer of tissue called a synovial membrane. The synovial membrane breaks down foreign matter in the joint and provides lubrication. The synovial membrane can become inflamed, the joint fills with excess fluid, and the extra force this generates during joint movement begins to wear away at the bone tissue. If you have synovitis, your knee will feel warm and look puffy.
Take heart, though -- only about one patient in 50 will have significant problems as a result of a total knee replacement [source: Mayo Clinic].