Knee Replacement
with Rajit Saluja, M.D
Arthritis can damage any joint in the body, but the weight-bearing hips and knees seem to suffer the most damage. Knee replacement is a newer procedure than hip replacement, but the number of knee replacement surgeries is growing. Surgeons prefer to operate on people in their 60s or older, but today people in their 50s are also having knee replacements, often because active baby boomers with worn-out knees have few other choices.
Good candidates
Dr. Rajit Saluja, an orthopaedic surgeon with Columbia St. Mary's, uses four criteria to determine if a patient requires surgery:
First, there are X-rays. "You can tell how much arthritis a patient has by getting standing X-rays. You can see the amount of cartilage height. The narrower it is, the more wear. If it's completely absent, it means the patient is walking bone on bone, which can be very painful," Dr. Saluja said.
Second, the doctor looks for malaligned joint, limited range of motion (such as patients who can't bend or straighten the leg) and knee instability.
Third, he examines such subjective criteria as how bad the pain is, how limiting it is for activities, and whether the pain also occurs when a patient is at rest.
Fourth, Dr. Saluja looks at what sort of previous treatments they've had, such as anti-inflammatory medications or injections. "We want to try other things first," he said.
Finally, he looks at the patient's age. "I prefer them to be at least in their 50s, though older is better," the doctor said.
The ideal candidate will also be in good health, at a good weight, and have good muscle tone in their legs. "Some people come to me with muscles in the back of the knee constantly bent, and the knee is tight due to a patient's compensating for pain. I can fix some of the problem in surgery but the recovery will take longer," Dr. Saluja said.
Avoiding the need for an artificial knee
While most knee replacements are caused by arthritic wear on the knee joint, people can take steps to reduce the amount of wear. Dr. Saluja listed three.
First, if someone has a ligament injury to the knee, it should be repaired and normal function restored as soon as possible after the injury. This will reduce the likelihood of arthritis causing problems later.
Second, people should manage their weight. "Even a few extra pounds puts a lot of extra stress on the knee," Dr. Saluja said.
Third, athletes should modify their activities to avoid problems. "If someone has a preexisting knee injury and is told it will lead to arthritis, instead of basketball or running, they should switch to swimming and lesser impact sports," Dr. Saluja said.
Rajit Saluja, M.D., Orthopaedic Surgeon
Columbia St. Mary's
"I had a lady in her sixties and she weighed about 280 pounds. Nobody wanted to do her surgery. I did both her knee replacements and she lost about a hundred pounds after surgery because she was able to become so active. Her first question after the second surgery was 'how soon can I return to my water aerobics?'
"Now you can't say everybody will do that well but for certain people who are highly motivated and are kept back by their knees, knee replacement surgery can have an incredible impact."
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The surgery
Knee replacement is inpatient surgery. Most of Dr. Saluja's patients come in the morning of surgery and those in fairly good health will require a four- to five-day hospital stay before going home. Older patients or those with health problems may require a longer hospital stay, usually in inpatient rehabilitation or a subacute unit.
The surgery uses a traditional incision because the size of the replacement joint cannot be done with an arthroscope. There is a trend towards utilizing smaller incisions but it is typically limited by the surgeon's ability to see all the problems in the joint. The type of replacement Dr. Saluja prefers is cemented. "The success rate for cementless knees was not as good as for the hip and few surgeons use cementless replacements today," the doctor said. Depending on the complexity of the surgery, it should take one to three hours.
Post-op rehabilitation
The goal of rehab is twofold. The first is to get the muscles that move the knee working again. These include the quadriceps and hamstrings. Second, the knee joint must be used so it doesn't get stiff. This is started as soon after surgery as possible. For patients whose muscles will not allow them to bend their knee on their own, a special machine, called a continuous passive motion machine, can be used. This bends the knee slowly and keeps the joint supple.
If possible, patients will be up and using a walker as early as the morning after their surgery. They should be walking with a cane by three to four weeks. By one month, patients should be able to use an exercise bike for rehabilitation and begin using a cane to walk. "By three months, most patients shouldn't need any functional aids to help them walk, but they may have some mild swelling or minor discomfort for up to a year. However three months is the usual recovery time," Dr. Saluja said.
Age…is it STILL an issue?
While surgeons say they do not like to put a replacement knee in a patient younger than 60, younger patients are having the surgery today.
"I've been seeing more and more people in their fifties with bad joints who are saying they are gaining weight because they can't exercise. You can't tell them to go home and come back when they are sixty years old. In this day and age, people want to do a bit more at fifty than they might have years ago. Fifty isn't considered old anymore," Dr. Saluja said.
