Reliability of center of pressure measures of postural stability in patients with unilateral anterior cruciate ligament injury

Abstract

The aim of this study was to estimate the test-retest reliability of some commonly used center of pressure measures in postural control investigations of sport injuries under the diverse stressful postural conditions. Twelve patients with anterior cruciate ligament injury were evaluated on two separate sessions. The center of pressure was recorded from force platform and the following measures were calculated (1) standard deviation of amplitude (2) mean velocity (3) standard deviation of velocity (4) phase plane parameters and (5) area (95% confidence ellipse). Relative and absolute reliability was assessed using intra-class correlation coefficient and coefficient of variation, respectively. Mean velocity and total phase plane parameters were the most reliable measures having high to very high correlation across all postural conditions. The mean and range of intra-class correlation coefficient for mean velocity and total phase plane parameters were 0.88 (range: 0.80 to 0.96) and 0.81 (range: 0.71 to 0.88), respectively. Interestingly, pattern of the coefficient of variation values was, to a great extent, consistent with the intra-class correlation coefficients. Therefore, mean velocity and total phase plane parameters may be sensitive center of pressure measures to differentiate balance between Anterior Cruciate Ligament (ACL) injured patients and to evaluate the effect of a rehabilitation program in this population. © 2008 Asian Network for Scientific Information.