Osteoarthritis, also known as degenerative joint disease, affects close to 21 million people in the US. And according to the Arthritis Foundation, osteoarthritis, or OA, in the knee or hip is the most common cause of arthritis-related disability. As baby boomers get older (and more arthritic), orthopaedic surgeons are performing more and more total joint replacement surgeries, with total knee replacements, or TKRs, the most common type. More than 300,000 people undergo the procedure each year, according to the American Academy of Orthopaedic Surgeons.

TKRs have been performed in the US since the 1960s, and today, knee replacement is one of the safest and most successful types of major surgery. In fact, in well over 90% of cases, TKR significantly reduces a patient's pain and restores his mobility -- without complications. A knee replacement can be expected to last for 20 or more years.

In a TKR, a surgeon resurfaces of the worn out parts of the knee and replaces the lost cartilage and diseased bone with a new device, made of metal alloys and high-grade plastics and designed to move just like a healthy human joint. Dr. Plancher does this minimally invasive. TKRs are most often performed on people with advanced OA, but they're also necessary in certain cases of traumatic injury or rheumatoid arthritis, an autoimmune disease. The common denominator in all TKR surgeries is a knee that's simply worn out.

OA can run in families, and it's usually worse in older people, whose joints have had more years of wear and tear, Dr. Plancher explains. But nobody knows why arthritis can be much worse in some people than others, or why it can occur in one knee and not the other. "We know that having a previous injury and being obese can exacerbate arthritis, but we also know that being physically active doesn't." Dr. Plancher notes that a major study published in early 2007 found no connection between physical activity -- even vigorous activity -- and OA. "Some people believed that the repetitive motions of physical activity, particularly in people who are overweight, might contribute to knee OA. But this study debunked that." Moreover, he notes, another study showed an actual benefit of exercise in building cartilage -- and staving off arthritis. Specifically, it showed that both casual and vigorous physical activities are associated with an increase in cartilage volume, and that those benefits increase with frequency and duration of exercise.

But what about people who's OA has advanced so far that they're considering joint replacement? Dr. Plancher says that appropriate physical activity is imperative for anyone with knee OA, and it can significantly improve the outcome of a total knee replacement operation. New research shows that patients who follow a program of exercise and rehabilitation, both before and after their surgeries, fare better than those who sit still.

For example, a 2006 study found that a six-week exercise regimen before a total knee replacement operation helped patients recover more quickly. One group did no exercise, while the other worked out three times a week, first in a pool (exercising spine, shoulders, arms and legs in chest-deep water), later on recumbent stationary bikes or elliptical machines. Patients also did strength training and stretches for flexibility during the program's last three weeks. After surgery, the exercisers were much more likely than the nonexercisers to go straight home following their discharge from the hospital (the nonexercisers were more likely to be sent to an inpatient rehabilitation facility before going home).

Earlier this year, another study showed that a preoperative rehabilitation program, including patient education as well as physical therapy, could improve postoperative outcomes after total knee replacement. And yet another study, also published this year, found that post-op exercise improved the functional activities of daily living, walking, quality of life, muscle strength, and range of motion in the knee joint.

The key to exercising for people needing TKR is to find activities that work the major muscle groups but place as little stress on the knee as possible. "We do have patients who return to very strenuous activity and walk more than three miles a day after a total knee replacement," says Dr. Plancher. "You shouldn't have any significant restrictions of your normal activities following knee replacement. But just remember that knee replacement, at times, can even return you to most sports."

Here are Dr. Plancher's recommendations for pre- and post-op exercise:

Before your surgery, do strengthening exercises to help stabilize the knee joint. "Getting stronger beforehand means you'll have an easier time in post-surgery rehabilitation and physical therapy," he says. In the case of TKR, that means working the muscles in your legs that surround and connect to the knee joint.

As soon as you can after surgery (typically within a couple of hours), start your physical therapy -- and get back on your feet as soon as you can (you'll probably be using a walker or crutches at first).

Pick the right activities. Generally speaking, TKR patients will be told to skip any activities that might injure the replaced joint. That means swimming and golf are great -- and sports that involve heavy lifting, running, and jumping are verboten. Many patients return to skiing and tennis after TKR.

Protect your knees. No matter what you're doing, take care of your knees. Avoid bending knees past 90 degrees when doing squats, avoid twisting your knees by keeping your feet as flat as possible when stretching, and always warm up and stretch before doing any physical activities.

Bio:
Kevin D. Plancher, M.D., M.S., F.A.C.S., F.A.A.O.S, is a leading orthopaedic surgeon and sports medicine expert with extensive practice in knee, shoulder, elbow and hand injuries. Dr. Plancher is an Associate Clinical Professor in Orthopaedics at Albert Einstein College of Medicine in NY. He is on the Editorial Review Board of the Journal of American Academy of Orthopaedic Surgeons and the American Journal of Medicine and Sports.

A graduate of Georgetown University School of Medicine, Dr. Plancher received an M.S. in Physiology and an M.D. from their school of medicine (cum laude). He did his residency at Harvard's combined Orthopaedic program and a Fellowship at the Steadman-Hawkins clinic in Vail, Colorado where he studied shoulder and knee reconstruction. Dr. Plancher continued his relationship with the Clinic for the next six years as a Consultant. Dr. Plancher has been a team physician for over 15 athletic teams, including high school, college and national championship teams. Dr. Plancher is currently the head team physician for Manhattanville College. Dr. Plancher is an attending physician at Beth Israel Hospital in New York City and The Stamford Hospital in Stamford, CT and has offices in Manhattan and Greenwich, Connecticut. www.plancherortho.com

Dr. Plancher lectures extensively domestically and internationally on issues related to Orthopaedic procedures and injury management. During 2001, 2002, 2003, 2004, 2005 and 2006, Dr. Plancher was named among the Top Doctors in the New York Metro area and was the New York State Representative for the Council of Delegates to the American Academy of Orthopaedic surgeons. In 2007 Dr. Plancher was named America's Top Doctor in Sports Medicine. For the past six years Dr. Plancher has received the Order of Merit (Magnum Cum Laude) for distinguished Philanthropy in the Advancement of Orthopaedic Surgery by the Orthopaedic Research and Education Foundation. In 2001, he founded "The Orthopaedic Foundation for Active Lifestyles", a non-profit foundation focused on maintaining and enhancing the physical well-being of active individuals through the development and promotion of research and supporting technologies. www.ofals.org.