Balance is difficult for people with injuries to their legs. It can be especially difficult for patients with arthritis. And poor balance can lead to more falls. Vision is one of the senses that can help patients compensate for balance problems caused by arthritic knees, and so can paying extra attention to balancing. How exactly do people with arthritis control their balance?
Researchers tested 18 patients with severe rheumatoid arthritis (RA) who were scheduled for total knee replacement surgery. These patients were compared with 23 other people who didn’t have arthritis.
First the researchers tested for knee stability. They had everyone stand on a special force plate to measure how much they swayed back and forth. The amount of fluctuation in movement is called center of pressure (COP). The researchers found that the RA patients had an average of 80% more fluctuation in COP than the control group. This showed that the RA patients had knees that were much more unstable and difficult to balance.
Next, everyone was tested for balance with eyes closed and again while doing math problems. The RA patients weren’t particularly affected by having to focus their attention on doing math problems. But with their eyes closed, they had a much more difficult time balancing than the control group. The more severe the RA, the more patients tended to rely on visual information.
This suggests that people with severe knee RA may end up getting fewer sensations about position and balance from their affected knee. It also indicates that people with severe RA are at greater risk for falling if for some reason vision is a problem. This can happen if eyesight isn’t sharp, if an obstacle blocks the view, or in the dark.
The authors recommend future research on whether people with RA show better balance after having total knee replacement surgery.