The dynamics of crouch gait in cerebral palsy [electronic resource]

This dissertation presents the first three-dimensional musculoskeletal simulations of individuals with cerebral palsy and has contributed to our understanding of how muscle contributions, joint loads, and the effects of muscle weakness change in individuals with cerebral palsy and crouch gait. The simulations created for these analyses have been made freely-available for researchers and clinicians to download, use, and evaluate at http://www.simtk.org/home/crouchgait/. This work has provided insight into the underlying dynamics of crouch gait and created pathways to improve treatment. The first objective of this dissertation was to examine how individual muscles contribute to motion during crouch gait. We evaluated how muscles contribute to joint and mass center accelerations to support and propel the body during crouch gait and how these contributions change with crouch severity. The results of these analyses indicated that crouch gait uses similar muscles to support and propel the body as unimpaired gait; however, larger and more sustained muscle activity is required during crouch gait, which contributes to the inefficiencies of this gait pattern. The second objective of this dissertation was to examine how the compressive tibiofemoral force changes in individuals with cerebral palsy and crouch gait. Knee pain is common among individuals with crouch gait and the results of this study demonstrated that tibiofemoral load increases quadratically with crouch severity. Individuals who walk in a severe crouch gait experience three-times the tibiofemoral load than during unimpaired gait. The elevated tibiofemoral forces during crouch gait could contribute to cartilage degeneration and knee pain. The final objective of this dissertation was to examine how muscle weakness may contribute to crouch gait. We used musculoskeletal simulations to determine how much muscle groups can be weakened and still reproduce mild and moderate crouch gait. The results of this analysis demonstrated that crouch gait requires greater quadriceps strength but less hip abductor and ankle plantarflexor strength than unimpaired gait; suggesting that these latter muscles may be better targets for strength training programs. We also performed a meta-analysis of individuals with crouch gait who had participated in strength training programs. This analysis demonstrated that outcomes after strength training are inconsistent, even among individuals with cerebral palsy and crouch gait. Hamstring spasticity was associated with poor outcomes after strength training and may be a contraindication for strength training. The long term goal of the work presented in this dissertation is to improve quality of life for individuals with cerebral palsy. The freedom to walk, explore, and interact with the world is a skill that many of us take for granted every day. Through the combination of musculoskeletal modeling and simulation, experimental studies, and clinical outcomes we can help individuals with gait pathologies achieve this freedom throughout their life.

Keywords: Mechanical Engineering
Advisor: Delp Scott primary advisor. Thesis advisor
Andriacchi Th. P. (Thomas P.) advisor. Thesis advisor
Rose Jessica advisor. Thesis advisor