Abstract
OBJECTIVE: To evaluate the changes in static and dynamic postural control after the development of acute low back pain. METHODS: Thirty healthy right-handed volunteers were divided into three groups; the right back pain group, the left back pain group, and the control group. 0.5 mL of 5% hypertonic saline was injected into L4-5 paraspinal muscle for 5 seconds to cause muscle pain. The movement of the center of gravity (COG) during their static and dynamic postural control was measured with their eyes open and with their eyes closed before and 2 minutes after the injection. RESULTS: The COGs for the healthy adults shifted to the right quadrant and the posterior quadrant during their static and dynamic postural control test (p<0.05). The static and dynamic instability index while they had their eyes closed was significantly increased than when they had their eyes open with and without acute back pain. After pain induction, their overall and anterior/posterior instability was increased in both the right back pain group and the left back pain group during the static postural control test (p<0.05). A right deviation and a posterior deviation of the COG still remained, and the posterior deviation was greater in the right back pain group (p<0.05). CONCLUSION: The static instability, particularly the anterior/posterior instability was increased in the presence of acute low back pain, regardless of the visual information and the location of pain.