Aging Begins at 30

Lessons I Learned At My Mother's Knee

My friend had had a knee replacement after a serious injury. Now her mother needed knee replacement because of arthritis and aging, but she was reluctant even to use a cane. Would I please write about the pros and cons of total knee replacement?

Dr. Borje Walldius in Sweden replaced knees in 1953 with a simple hinge joint but knees are complex and these replacements often loosened. In Canada and the US a joint was developed supported only by the patient's muscles and ligaments. About 130,000 replacements are performed yearly in the U.S. at a cost of $25-30,000 each. The new knee has to be tough. The stress through the knee, including the knee cap, can reach five times the body's weight with normal activity The lower artificial joint surface is polyethylene and the upper surface is chrome-cobalt or titanium and much like a rolling pin in a trough. They are fixed to the bones with methyl methacrylate cement or by allowing bone to grow into a mesh. Most patients are over age 55.

You may need a new joint if you have severe arthritis on x-ray and knee pain interferes with living. You need the operation if your knee is very stiff, unstable, or is severely deformed (knock knees, bow legs, rheumatoid arthritis, or hemophilia deformity). You need 65 degrees (one third of an arc) of bending to walk normally, 95 degrees to climb stairs and 110 degrees to easily rise from a chair. You will tell the surgeon when you are ready. He or she doesn't make the decision, except to determine your disease is bad enough to warrant the procedure.

With a new knee, 90% of you will get pain relief, 90% will have a satisfactorily functioning knee. Eighty percent can climb stairs without support. You will be stable back to front, and only 3% will be unstable sideways. About 2% of you will need a revision operation in 5 years. Loosening and wear continues with time. Usually it's the shin bone attachment that fails. The knee cap can fracture or be displaced. Rarely patients get deep calf vein clots with clots in the lung. Knee infection is the most serious complication occurring in less than 1%. After drainage, antibiotics, and implant removal, a second implant has a 90% success rate. Being overweigh will shorten the life of the implant. Knee infection before operation is an absolute contraindication to operation at that time.

After the operation you will be in bed one day, maybe two, first with a "continuous positive motion unit" that slowly stretches and bends your leg, then physical therapy will begin. The strengthening of the muscles around the knee is something that you must do for yourself not something the therapist does for you. Pain medication may be needed before exercise at first. A padded knee immobilizer is worn while walking and sleeping and an elastic stocking to help prevent blood clots. If the artificial knee was put in without cement full weight bearing will not occur until 3 months after the operation. You will be out of the hospital in about one week. Check ups occur at 2 and 6 months after the operation and also 1,2,3 and 6 years. There will be no car driving until you are checked at 2 months but you can return to work at 3 months. Sex can be resumed after your 2 month check-up. If you get a bacterial infection such as pneumonia, a strep throat, a boil or bladder infection or if you have a tooth pulled or infected you will need antibiotic treatment to avoid spreading the infection to your precious new knee. Swimming, cycling, golfing, bowling, and cross country skiing can be resumed after knee replacement healing, but not running, football, basketball, soccer or karate.

One friend kept putting off the operation and had a less than satisfactory result because her stabilizing muscles had withered. Is the operation worth it? Numerous patients have told me it gave them new life and kept them out of the nursing home, but remember no one else can decide for you.

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See related Patient Topics Bones, Joints and Muscles, Injuries and Wounds or Knee Injuries and Disorders.

See related Provider Topics Bones, Joints and Muscles, Injuries and Wounds or Knee Injuries and Disorders.

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