Effects of the surface instability degrees on dynamic postural stability in anterior knee pain patients and healthy subjects

Anterior knee pain (AKP) is one of the common problems in active people specially، women. One of the consequences of this impairment is its effects on postural control which include static postural stability to dynamic activities. The aim of this study was to compare functions of patients with AKP according to different levels of sensory information and perturbation and the study of the interactions between these factors. A case – control study was performed on two groups of 30 (18-35 years) healthy subjects and AKP patients. Balance was evaluated in two different occasions; standing on the affected limb on two different unstable levels of Biodex stability system with eyes open and eyes closed. Total stability index and percent maintaining in zone A were evaluated for postural control. Multiple analyses of variance showed that the main effects of health status (p=0. 04)، base of support (P = 0. 000) and visual information (P = 0. 000) and the interaction between visual information and base of support (P = 0. 002) on total stability index were significant. The result of this study emphasizes the importance of properioception and visual information on the maintenance of dynamic balance. The dependence of both studied groups on visual information in the difficult levels of postural task was another finding of this study