by Carol Milano

Less pain, faster recovery, and reduced scarring are benefits of small-incision TKR

Of all the surgical options for knee arthritis, only total knee replacement is viewed by doctors as a long-term cure. Says Dr. Peter Brooks, a Cleveland Clinic orthopaedic surgeon, "It's the only procedure in which you're removing everything that is, or could become, diseased -- the cartilage, the linings, the ends of the bones."

However, total knee replacement (TKR) has its drawbacks. The recovery period can be long, difficult, and painful. The procedure involves an incision on the quadriceps tendon and the moving, or flipping, of your kneecap -- a procedure referred to as "patella eversion." Infection or other medical complications are possible. Finally, there's that long, unsightly scar.

Now, a new, less invasive surgical technique -- Mini-Incision TKR (MI-TKR)-allows patients who undergo knee replacement to experience less pain and recover more quickly. Developed by Dr. Steven B. Haas, associate chief of Knee Service at the Hospital for Special Surgery (HSS) in New York City, the procedure allows patients to regain range of motion in four to six weeks, compared to the three months or more following conventional TKR surgery. Other benefits include less trauma, no disturbance of surrounding tissue, no patella eversion, reduced chance of infection, and less scarring.

Conventional TKR

Traditionally, a total knee replacement involves an 8-to-12 inch incision over the front of the knee. Although not directly involved, the quadriceps tendon is cut around the kneecap to expose the knee. Dr. Haas wondered, "Is it possible to avoid cutting uninvolved tendons? Do we really have to go through all that to get to the knee? Can we get rid of the big incision?"

Typical TKR instruments are large, so they require an incision big enough to accommodate them. So Dr. Haas began to design smaller instruments -- about half the size of conventional instruments.

How MI-TKR Differs

In small-incision TKR, the quad tendon is not cut. Beginning at the kneecap, the surgeon spreads the underlying muscle fibers, makes the identical bone cuts that are made in a large-incision procedure, and inserts the same implants. The new instruments make it all possible. They're smaller and more strategically designed, with rounded edges that are easier on skin and tendons. They allow the surgeon more flexibility in how to make the necessary cuts, through incisions of only 3.5 to 5 inches -- less than half the size of a standard TKR.

Faster Recovery Time

The major advantage of small-incision TKR is recovery time, which has always been patients' biggest complaint about the traditional procedure. "Small-incision TKR gets them moving faster," says Dr. Haas. "Most people can lift their leg, straight, off their hospital bed in three or four days. They are able to do more when they return home, but they will still have pain and will need to take medication to relieve it."

Another advantage is that small-incision patients progress much faster in regaining range of motion, the hardest part. At four to six weeks, average range of motion is nearly 15-20 percent greater than with a traditional TKR. Small-incision surgery leaves less scarring inside the knee, which is what limits motion and causes pain. Some patients, Dr. Haas claims, have returned to work in two or three weeks, compared to the typical four to six weeks they need to recover following traditional TKR.

Who's a Candidate?

Approximately 70-75 percent of people with advanced arthritis who are candidates for knee replacement are eligible for small-incision TKR. The ideal weight for women is under 225 pounds; for men (because of larger muscle mass), maximum weight is in the 200-210 pound range. Though age is not a disqualifying factor, obese patients are not considered candidates. The procedure, adds Dr. Haas, is not suited to patients with numerous scars over their knees from previous surgeries.

When should you consider a total knee replacement -- traditional or small-incision? "When arthritis significantly limits your ability to function," advises Dr. Haas. "If you can still walk a mile and climb steps normally, that's not the time. But if you have chronic knee pain or your quality of life is deteriorating because of it, get evaluated."

According to Dr. Kenneth Marks, Editor of Arthritis Advisor and an orthopaedic surgeon at The Cleveland Clinic, many medical centers have already begun training their surgeons to reduce the size of the TKR incision. "We've been deliberately decreasing it, using traditional instruments, down to six or seven inches. It's the right idea -- the less trauma to the knee, the faster a patient recovers."

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