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Under the watchful eye of Lynn Snyder-Mackler at the University of Delaware's Physical Therapy Clinic, T. Fraser Russell demonstrates one of the quadriceps strengthening exercises that enhanced his recovery from total knee placement surgery.

X-ray of total knee replacement (lateral view).

8:07 a.m., Feb. 4, 2009----It may be uncomfortable at first, but doing exercises to strengthen your quadriceps after you've had knee replacement surgery due to osteoarthritis is critical to your recovery. In fact, it can boost the function of your new knee to nearly that of a healthy adult your age.

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That's the finding of a University of Delaware study published in the February issue of Arthritis Care & Research.

The authors include Lynn Snyder-Mackler, Alumni Distinguished Professor of Physical Therapy at the University of Delaware, Stephanie Petterson, clinical faculty at Columbia University, Ryan Mizner, an assistant professor at Eastern Washington University, Jennifer Stevens, an assistant professor at the University of Colorado at Denver, and Drs. Leo Raisis, Alex Bodenstab, and William Newcomb of First State Orthopaedics in Newark, Del.

Petterson, Mizner and Stevens all received their doctorates in the Biomechanics and Movement Science (BIOMS) program at the University of Delaware.

“It sounds logical that exercises to strengthen your knee should be a component of your post-operative physical therapy after a total knee replacement, but it's not the convention at all,” says Snyder-Mackler.

“There are all of these old wives' tales that strength training is a detriment to the patient and that the new knee should be treated delicately,” Snyder-Mackler notes. “Our study demonstrates that intensive strength exercise as outpatient therapy is critical to begin three to four weeks after surgery.”

Quad strengthening key to TKA recovery

Nearly a half-million knee replacements, also known as total knee arthroplasties (TKAs), are performed every year in the United States to treat severe knee osteoarthritis, the loss of the cushiony cartilage padding the knee. The joint disease leaves its sufferers with persistent pain and limited function, resulting in an overall diminished quality of life.

While knee replacement alleviates the pain of osteoarthritis and improves function, patients exhibit impaired quadriceps strength and function for such activities as walking and climbing stairs, and the levels remain below those of healthy people of the same age.

In a randomized controlled trial at the University of Delaware's Physical Therapy Clinic conducted between 2000 and 2005, 200 patients who had undergone knee replacements were given six weeks of progressive strength training two or three times a week starting four weeks after surgery. Half of the group also received neuromuscular electrical stimulation (NMES).

Their function was compared to that of 41 patients who received conventional rehabilitation and home physical therapy. Quadriceps strength, knee range of motion, and gait were measured in such tests as timed up and go, stair climbing and a six-minute walk.

The group in the progressive strength-training program showed significant improvement in quadriceps strength and functional performance. They also demonstrated substantially greater quadriceps strength and functional performance after 12 months than the group that underwent conventional rehabilitation.

“This study clearly demonstrates the importance of surgeons encouraging their patients to be compliant with progressive quadriceps strengthening during their rehabilitation to enhance their clinical improvement and function post-total knee replacement,” notes Dr. Leo Raisis, a total joint surgeon at First State Orthopaedics and adjunct associate professor at the University of Delaware.

Raisis was one of the lead total joint surgeons on the study and also participated in the study's design and manuscript preparation. He has been in practice for over 20 years and currently serves as chairman of the Center for Advanced Joint Replacement of the Christiana Care Health System.

“Why undergo a $25,000 elective surgery and then not do as much as you can to get the most out of it and improve your quality of life?” Snyder-Mackler says. “Older people are incredibly motivated-they hurt after the surgery and they want to be better. They need to do this.”

Study participant benefits from experience

T. Fraser Russell, the Allan P. Colburn Professor of Chemical Engineering at the University of Delaware and chief engineer at UD's Institute of Energy Conversion, participated in the study in 2003 at the time of his first knee replacement.

In October 2008, he had his other knee replaced and says he sought out and again benefited from the quadriceps strength training program at the University's Physical Therapy Clinic, which is located on the ground floor of McKinly Laboratory.

“The stretching exercises are painful, but it's absolutely critical to do the physical therapy in the clinic and then do a set of exercises at home,” Russell says.

His most recent surgery was on Oct. 13, and by Dec. 13, he says, he was well on the way to recovery.

“My knee strength was already up to 1,000 Newtons, which is normal, over the holidays,” he says. “I'm an engineer, so I'm interested in that measure,” he explains.

Today, he can walk in a nearby park for a couple of hours at a time and go up and down stairs with ease.

“My knee is essentially restored to normal,” Russell says. “I'm really very pleased with what they do at the clinic,” he notes. “I'm gratefully in favor of and appreciate what they do.”

Article by Tracey Bryant
Photo by Ambre Alexander