Repositioning error in low back pain - Comparing trunk repositioning errorin subjects with chronic low back pain and control subjects

Study Design. Repositioning error of the trunk was tested in 20 subjects wi th chronic low back pain and in 20 control subjects. The 3Space Tracker (Po lhemus, Colchester,VT), a device that measures three-dimensional position i n space, was used to determine the subject's trunk position. Objectives. To determine whether repositioning error is different in subjec ts with chronic low back pain than in control subjects. Summary of Background Data. Proprioception allows the body to maintain prop er orientation during static and dynamic activities. In peripheral joint in juries, researchers have demonstrate a loss of some aspects of propriocepti on and improvement in outcome with retraining. Although the components of p roprioception in subjects with low back pain have not been well studied, it is thought that these persons lose some elements of proprioception that ca n be measured in a quantifiable way. If so, then rehabilitation to improve these deficits is important. In this pilot study, one aspect of propriocept ion, repositioning error, was examined. Methods. The subjects attempted to replicate target positions of the trunk in flexion, extension, lateral bending, and lateral rotation. Repositioning error was calculated as the absolute difference between the actual and the subject-replicated target positions. Results. No significant difference was found in repositioning error between the control subjects and the persons with chronic low back pain. Conclusions. Because proprioception is complex and entails the use of many afferent receptors, it is difficult to measure any one afferent deficiency discretely. The authors believe that this study, in which one aspect of pro prioception was measured in an indirect manner, provides important backgrou nd information on low back position sense. Further studies analyzing aspect s of proprioception in subjects with low back pain are recommended.