Are you part of the .2%? Each year, thousands of people in the United States have knee replacement surgery — about 600,000 to be exact, according to the Agency for Healthcare Research and Quality. Robert L. DeMaagd, MD, specialist with the Total Joint Center at Orthopaedic Associates of Michigan, sees his fair share. “I do close to 300 knee replacements each year,” says Dr. DeMaagd. “That includes both partial and total replacements.”
Who is a candidate for knee replacement? According to Dr. DeMaagd, most knee replacement patients are between 55-75 years old. “Typically knee replacement surgery is done for chronic osteoarthritis of the knee joint that has not been successfully treated with non-operative means like medication, bracing, injections, and physical therapy,” he explains. “Arthritis is an inherited trait, so for most people, it’s just a genetic wearing out of the joint.”
Time to move on “Many of these non-operative treatments can be good for mild to moderate arthritis, and you can go for years without joint replacement surgery,” Dr. DeMaagd says. “But after a while, those measures just don’t work. You have to move on to something else.” That’s when patients typically contact OAM. “If the knee pain and stiffness are affecting a patient’s quality of life or getting in the way of normal daily activity, the patient is probably a good candidate for a knee replacement,” says Dr. DeMaagd.
Total vs. Partial: Do I have a choice? Whether a patient is a candidate for a total knee replacement or a partial knee replacement depends primarily on the condition of the various parts of the knee. Very simply, the knee is separated into three main compartments: the medial compartment (along the inside of the knee), the lateral compartment (along the outside of the knee), and the patellofemoral compartment (the front of the knee between the kneecap and thighbone). “If two or three of the compartments are damaged by arthritis, we would do a total knee replacement,” explains Dr. DeMaagd. “We would also do a total if the patient has a complication such as deformity caused by long-term arthritis, or if they have severe ligament instability. These can’t be corrected with a partial replacement.” Most patients who need knee replacement surgery need total joint replacement. However, in some cases, just one compartment is affected by arthritis. “Perhaps someone had some meniscus or cartilage taken out of their knee when they were young and only that portion of the knee has deteriorated. That person would be a perfect candidate for a partial knee replacement,” says Dr. DeMaagd.
The art and science of total knee replacement “In a total knee, all the surfaces of the knee are recovered with metal and plastic devices,” explains Dr. DeMaagd. “Most people think the surgery ends there, but that’s really the simplest part of the procedure.” Knee arthritis can naturally wear away the joint on one side or another. This can cause deformity, where the patient becomes severely bow-legged or knock-kneed. Both conditions stretch the ligaments on one side of the knee and cause ligaments on the other side to tighten. “The more difficult part of the procedure is balancing the ligaments and obtaining a good stable knee,” Dr. DeMaagd goes on to explain. “That’s where a lot of the science, but also the art of knee replacement come into play.” He says almost every total knee replacement he performs requires some degree of ligament work. In the end, total knee replacements are considered to be very safe and effective for treating the pain and stiffness caused by osteoarthritis of the knee, particularly among the 55-75 year old population. Most people can get back to work and activities of daily life after about eight weeks, and the knee will be fully healed in about a year. While there are restrictions — things like jumping from heights, running, and singles tennis aren’t recommended — people with a total knee replacement may golf, walk, bike, swim, play doubles tennis, and even ski at moderate levels. But the science does have limitations. “After a full replacement, most people can feel they have a replacement knee,” points out Dr. DeMaagd. “While the pain is gone, they can definitely feel the difference — the replacement knee feels slightly mechanical, maybe a little stiffer than their real knee making it difficult to squat or kneel.”
Partial knee, full advantage In a partial knee replacement, just one compartment of the knee is resurfaced — the inside or the outside. Additionally, this procedure usually doesn’t include the ligament balancing that’s done with a total knee replacement. The big advantages are that the partial knee replacement is typically done in an outpatient setting and it’s less invasive, quicker to heal, and feels more like a normal knee than a full knee replacement. Partial knee patients usually experience more flexibility, as well, and are often able to squat and kneel after surgery. “Many people who get a partial replacement feel their knee is almost back to normal,” says Dr. DeMaagd. “Most people can’t really tell the difference between a normal knee and a partial replacement.” Initial recovery time is cut in half. “Most people are off crutches or a walker within several days and generally get back to most activities of daily living after about three to four weeks,” says Dr. DeMaagd. Full healing still requires about a year, and the same restrictions on high-impact exercises apply. The good news is, if a patient qualifies for a partial knee replacement, they can expect to enjoy most of the same recreational sports and activities that they enjoyed pre-surgery — except without the pain.