Background: Individuals with hemiparesis resulting from cerebrovascular accident often demonstrate uncontrollable sliding of the paretic lower extremity when attempting to lift their pelvis from a hook-lying position (bridging), during bed mobility. This disorder is often attributed to hypertonicity of the knee extensors, though this assumption has not been confirmed experimentally.
Purpose: To determine the interaction of limb sliding during bridging with impairments of motor control, knee moments, and spasticity.
Methods: Twenty-seven adults with hemiparesis were assigned to 2 groups on the basis of their ability to perform bridging on a smooth surface. The association of the dichotomous parameter of bridging performance (success/failure) with the other parameters was determined by point biserial correlation, and the predictability of limb sliding was estimated from binary logistic regression. A 2-way repeated-measures analysis of variance was used to determine the differences between knee moments.
Results: The group that could perform bridging without sliding had higher moments of the paretic knee flexors and a higher level of motor control than the other group (P = .001). The moments of the paretic flexors and the level of motor control were also correlated with limb-sliding occurrence (r = 0.61 and 0.74, respectively) and served as the best predictors of bridging performance. The paretic knee's flexion moment was found to be more affected than the extension moment (P = .04).
Conclusion: Low level of motor control and reduced strength of the knee flexors are 2 major deterrents of successful bridging in persons with hemiparesis. The predominant decline of the flexors' moment may reflect a more severe disruption of the flexors' cortical innervation or superior recovery of the extensors.