Nearly 600,000 knee replacements are performed each year in the U.S. on patients whose knees have been severely damaged by arthritis or injury, according to the Cleveland Clinic. The procedure involves replacing damaged cartilage and gliding surfaces of the joint. One of six types of artificial knee implants are used, depending upon the needs of the patient. The artificial parts are made of cobalt chrome, titanium or plastic, and can be affixed to the bone with acrylic cement or fitted into the area without cement.
Risks of Surgery and Anesthesia
Anyone undergoing surgery risks the development of blood clots in the leg, heart attack, stroke, blood loss, wound infection, nerve damage or a reaction to the anesthesia. Fewer than 2 percent of patients undergoing knee replacement surgery experience serious complications, according to the American Association of Orthopaedic Surgeons. In extremely rare cases, according to the National Institutes of Health, an allergic reaction to the cement used in the surgery may cause death.
Infection can occur years after knee replacement surgery, when bacteria enter the bloodstream and infect the surgical site, according to MayoClinic.com. The most common causes are dental or surgical procedures, urinary tract infections and skin infections. Symptoms include fever higher than 100 degrees F, shaking, chills, drainage from the surgical site or redness, swelling, tenderness and pain in the knee. Treatment focuses on clearing the infection with antibiotics and removal of the artificial parts. A second surgery can be done later to replace the joint, but each additional surgery diminishes the chances of a successful outcome.
Pain and Stiffness
Rarely, patients may experience more pain in the knee after surgery, according to the National Institutes of Health. More than 90 percent, however, find that surgery drastically reduces their pain and improves their ability to perform normal activities, reports the American Academy of Orthopaedic Surgeons. The expected range of motion in the joint is about 115 degrees, but motion will be more limited if scarring occurs.
Failure of the Artificial Joint
Approximately 85 percent of knee implants last 20 years, according to the Cleveland Clinic. Most patients undergoing total knee replacement surgery are between the ages of 60 and 80, but it can also be performed on younger patients who are disabled by their disease. Those in the lower age ranges will require replacement surgery when the artificial parts begin to fail. The risk of joint failure is highest among young, obese males and patients with complicating conditions, according to MayoClinic.com. Avoiding excess wear and tear, especially from jogging or running, contact sports or other vigorous activities extends the life of the artificial joint.