Each year in the United States, approximately 581,000 people receive total knee replacements, states the American Academy of Orthopaedic Surgeons. Arthritis, the most common reason for knee replacement, occurs most often in people over age 50 and causes pain, difficulty performing normal activities or deformities that lead to a need for total knee replacement. A total knee replacement performed in 2010 will last 15 to 20 years in more than 85 to 90 percent of people, according to the Hospital for Special Surgery. As with every surgery, however, complications can occur.
Deep Vein Thrombosis
Deep vein thrombosis, or DVT, is the formation of blood clots within the lower leg. It occurs in as many as 60 percent of all people after total knee replacement surgery, according to the Merck Manual of Geriatrics. Swelling, warmth, pitting edema, pain and tenderness may accompany DVT. The use of low-molecular-weight heparin, a blood thinner with a reduced risk of bleeding and complications compared with regular heparin, and intermittent compression boots, which keep blood moving in the veins, can reduce the risk of DVT in the knee or thigh to 5 to 10 percent after total knee replacement, the Merck Manual states. Continuous passive motion machines that keep the affected limb moving after surgery also prevent blood from stagnating in the veins.
Infection
Infection in the knee joints affects fewer than 1 percent of patients who have total knee replacement surgeries, the Hospital for Special Surgery reports. Infection occurs because the metal and plastic components provide a place for bacteria to attach in a location that is difficult for antibiotics to reach. Infection can occur many years after surgery, warns the Mayo Clinic. Signs of infection include fever higher than 100 degrees Fahrenheit, chills and pain, tenderness, redness or swelling around the knee joint. A surgeon may need to wash out or completely replace the artificial joint to treat the infection. If removal becomes necessary, a surgeon removes the original parts and inserts an antibiotic-impregnated cement spacer. The surgeon removes the spacer in a second surgery, during which a new prosthesis is placed.
Wear and Loosening
Implants in total knee replacement often loosen or become worn over time. Aseptic loosening, the most common reason for total knee replacement failure according to the Hospital for Special Surgery, occurs when the bond that holds the implant to the bone is destroyed during the course of normal bone destruction, called osteolysis. Pain, instability and fractures may occur. Revision surgery to replace the failed joint is necessary. Young, overweight men have a higher rate of failure from wearing and loosening, the Mayo Clinic reports.
Reduced Range of Motion
The expected range of motion after total knee replacement is 115 degrees, according to the American Academy of Orthopaedic Surgeons. Scarring after surgery may result in reduced range of motion, especially in people with prior limited motion.
