Patients Must Re-learn Going From Sitting To Standing After Total Knee Replacement

"Because most patients with knee replacement have lived with debilitating pain for years, they work around the pain by adopting different strategies to avoid using their weakened quadriceps femoris muscle (muscle in front of the thigh) when going from a sit-to-a-stand position," says Lynn Snyder-Mackler, PT, ScD, SCS, ATC, FAPTA, distinguished alumni professor in UD's Department of Physical Therapy and a certified sports physical therapist and athletic trainer who was one of the study investigators.

The study, which evaluated 12 patients three months and one year following total knee replacement surgery, showed that the patients relied on a larger hip extensor movement (leaning far forward to rise) to perform the sit-to-stand task. "What is interesting about the study," notes Snyder-Mackler, "is that it shows that, even following surgery, this strategy continued as patients' muscle strength improved." The strategy, although dangerous because of the risk of falling, had become second-nature to them, observed Snyder-Mackler. "Simply put, it was a learned movement pattern that could not be resolved without retraining by a physical therapist, usually beginning 4-6 weeks after surgery when weight can be put equally on both legs," she concluded.

Snyder-Mackler found that, in order to get up from a chair, patients would bend forward at the hips and use the hips to stand up, moving the center of gravity forward. This makes the task easier, but is less stable and could lead to falls. The retraining would involve teaching the patient to rise up from the chair without bending forward, most likely by allowing the use of the arms to help push up in order to develop the correct pattern and eventually moving to performing the task without the use of the arms. "Because the incorrect movement pattern could potentially contribute to the development of future knee osteoarthritis, retraining may be an important prevention strategy," concluded Snyder-Mackler.

Physical therapists are health care professionals who diagnose and manage individuals of all ages who have medical problems or other health-related conditions that limit their abilities to move and perform functional activities in their daily lives. Physical therapists examine each individual and develop a plan of care using treatment techniques to promote the ability to move, reduce pain, restore function, and prevent disability. Physical therapists also work with individuals to prevent the loss of mobility by developing fitness- and wellness-oriented programs for healthier and more active lifestyles.

The study was originally published in Physical Therapy (May 1, 2008), the scientific journal of the American Physical Therapy Association (APTA).