Effect of visual input on normalized standing stability in subjects with recurrent low back pain

Although a number of studies have evaluated kinematic stability changes in subjects with low back pain (LBP), the combined sensitivity of normalized standing stability from the ground force and kinematic rotational angle of the body segment were not carefully examined for postural responses. The purpose of this study was to evaluate normalized standing stability in subjects with and without recurrent LBP while they stood quietly with the tested foot parallel to the other lower extremity at hip width. The subjects were then instructed to stand freely on one leg for 25 s with the contra lateral hip flexed 90° based on dominance side (dominant leg vs. non-dominant lower extremity) and visual condition (eyes open vs. eyes closed). A total of 42 subjects (27 subjects without LBP and 15 subjects with LBP) participated in the study. The dominant leg standing stability was significantly different during the eyes closed condition (0.68±0.30 for control vs. 0.37±0.32 for LBP, T=-3.23, p=0.002) compared to the eyes open condition. The standing kinematic stability, especially of the dominant thigh, was greater in the control subjects than in the subjects with LBP (T=-2.43, p=0.02). This sensitive detection of kinematic imbalance with postural stability is important for effective rehabilitation strategies and to understanding compensatory mechanisms in subjects with recurrent LBP.