NEWARK, Delaware—A progressive quadriceps strengthening program may help total knee arthroplasty patients approach the functional level seen among healthy peers, according to a new report published in the February issue of Arthritis Care & Research.1

“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 [but] our study demonstrates that intensive strength exercise as outpatient therapy is critical to begin three to four weeks after surgery.”—Lynn Snyder-Mackler, PT
“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,” said lead author Lynn Snyder-Mackler, PT, an Alumni Distinguished Professor of Physical Therapy at the University of Delaware in Newark, in a press release. “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 [but] our study demonstrates that intensive strength exercise as outpatient therapy is critical to begin 3 to 4 weeks after surgery.”

Strength quads to regain function after knee arthroplasty

The new study comprised 200 patients who had undergone a total knee arthroplasty (TKA) and 41 patients who received inpatient rehabilitation and home physical therapy. The 200 patients received 6 weeks of progressive strength training 2 or 3 times a week targeting their knee extension, range of motion, kneecap mobility, quadriceps strength, pain control, and gait. Half of this group also received neuromuscular electrical stimulation (NMES).
Lead author Lynn Snyder-Mackler works with a total knee replacement patient. Photo courtesy of University of Delaware.

The TKA patients who participated in the strength training program showed significant improvements in their quadriceps strength and muscle activation, functional performance and self-reported function, compared to their counterparts in the more conventional rehab. The patients in the strength-training group also demonstrated substantially greater quadriceps strength and functional performance after 12 months than the group who underwent conventional rehabilitation. There were no significant differences between the group that just did exercise and the group that did exercise plus NMES, the study showed.
 
Quadriceps strength is best predictor of recovery

In the study, quadriceps strength is related to functional performance and is the single greatest predictor of function for activities such as rising from a chair or climbing stairs. Functional performance typically peaks about 3 years following surgery and slowly declines in the following 10 years. But "failing to obtain adequate functional recovery may accelerate functional decline and predispose these individuals to an early loss of functional independence as they age," according to the study authors. "Our data suggest that individuals who do not undertake an intensive rehabilitation program following TKA are clearly at a disadvantage," the study authors conclude.

References
1. Petterson SC, Mizner RL, Stevens JE, et al. Improved function form progressive strengthening interventions after total knee arthroplasty: a randomized clinical trial with an imbedded prospective cohort. Arth Care Res. 2009;61:174-183.