Mon, Apr 18
Speaker: Melanie Fox (Stanford University)
Title: Using simulation to understand the causes and functional mechanism of treatment for stiff-knee gait in cerebral palsy
Abstract: Many children with cerebral palsy walk with a stiff knee gait, or a reduction and delay in swing phase knee flexion, which causes tripping or energy-inefficient compensatory movements. Since over-activity of the rectus femoris is commonly implicated as the cause, the most common treatment is transfer of the distal end of the rectus femoris behind the knee. Outcomes, though positive on average, are variable among individual subjects, with some subjects demonstrating unimproved or worsened knee flexion postoperatively. This variability is due in part to insufficient understanding of the biomechanical causes of stiff-knee gait and the functional effects of surgical treatment.
Computer simulation is a valuable tool for investigating gait pathologies. The transformation from muscle excitations to coordinated multi-joint movement is highly complex, involving multiple interdependencies at many levels. Also, the influence of a muscle on joint motions, especially those which it does not span, is not always intuitive. Muscle-driven, dynamic simulation provides a valuable tool for identifying biomechanical factors contributing to stiff-knee gait and evaluating the biomechanical effects of treatment options.
This work used computer simulation of both stiff-knee and unimpaired gait to clarify commonly overlooked preswing rectus femoris activity as a cause of stiff-knee gait, demonstrate the functional mechanism of improvement following transfer surgery, and identify other potential causes of stiff-knee gait. The motivation for this work was to contribute to the understanding of stiff-knee gait as a step towards improving indications for treatment and reducing the variability of surgical outcomes.
Host: Li-Qun Zhang