The goal of this work is to establish a scientific basis for treating crouch gait, one of the most common movement abnormalities among children with cerebral palsy. Crouch gait is characterized by persistent flexion of the knee, which is usually accompanied by excessive flexion, adduction and internal rotation of the hip. It is a highly inefficient means of locomotion; if not corrected it often leads to bone deformities, osteoarthritis, and senous, life-long physical limitations. Musculoskeletal surgeries are frequently performed in an effort to improve knee extension. However, it is extremely difficult to predict which patients will benefit from these procedures, in part, because the factors that cause excessive knee flexion are not known. This study will result in dynamic simulations of crouch gait that can identify the underlying biomechanical sources of patients' movement abnormalities and predict the functional consequences of common interventions.
Aims 1 -3 will rigorously examine several hypothesized causes of crouch gait, including spasticity of the hamstrings and psoas muscles, weakness of the hip, knee, and ankle extensors, and deformities of the femur and tibia. Forward dynamic simulations will be created that reproduce experimentally measured movement kinematics and kinetics of 45 subjects with cerebral palsy. A series of simulations of varying complexity will be analyzed to determine which of the hypothesized causes of crouch gait contribute to each subject's persistent knee flexion.
Aim 4 will evaluate the utility of our dynamic analyses for guiding treatment decisions by determining whether subjects have good (poor) outcomes when interventions are performed that agree (disagree) with the results of our simulations. This work will provide improved guidelines for deciding which patients should undergo surgical lengthening of the hamstrings and/or psoas muscles to correct crouch gait, and which patients are likely to benefit more from other treatments, such as strengthening exercises or bracing. Although multijoint movement abnormalities such as crouch gait are exceptionally complex, the development of dynamic simulations that elucidate how muscles contribute to movements in normal, impaired, and surgically altered limbs, as proposed here, is an important and necessary next step toward designing more effective treatments.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD033929-06
Application #
6621765
Study Section
Geriatrics and Rehabilitation Medicine (GRM)
Program Officer
Shinowara, Nancy
Project Start
1996-06-01
Project End
2005-11-30
Budget Start
2003-02-01
Budget End
2004-01-31
Support Year
6
Fiscal Year
2003
Total Cost
$313,151
Indirect Cost
Name
Stanford University
Department
Biomedical Engineering
Type
Schools of Engineering
DUNS #
009214214
City
Stanford
State
CA
Country
United States
Zip Code
94305
Seth, Ajay; Hicks, Jennifer L; Uchida, Thomas K et al. (2018) OpenSim: Simulating musculoskeletal dynamics and neuromuscular control to study human and animal movement. PLoS Comput Biol 14:e1006223
Hamner, Samuel R; Seth, Ajay; Steele, Katherine M et al. (2013) A rolling constraint reproduces ground reaction forces and moments in dynamic simulations of walking, running, and crouch gait. J Biomech 46:1772-6
Arnold, Edith M; Hamner, Samuel R; Seth, Ajay et al. (2013) How muscle fiber lengths and velocities affect muscle force generation as humans walk and run at different speeds. J Exp Biol 216:2150-60
Hamner, Samuel R; Delp, Scott L (2013) Muscle contributions to fore-aft and vertical body mass center accelerations over a range of running speeds. J Biomech 46:780-7
Steele, Katherine M; Seth, Ajay; Hicks, Jennifer L et al. (2013) Muscle contributions to vertical and fore-aft accelerations are altered in subjects with crouch gait. Gait Posture 38:86-91
John, Chand T; Anderson, Frank C; Higginson, Jill S et al. (2013) Stabilisation of walking by intrinsic muscle properties revealed in a three-dimensional muscle-driven simulation. Comput Methods Biomech Biomed Engin 16:451-62
Wang, Jack M; Hamner, Samuel R; Delp, Scott L et al. (2012) Optimizing Locomotion Controllers Using Biologically-Based Actuators and Objectives. ACM Trans Graph 31:
Draper, Christine E; Quon, Andrew; Fredericson, Michael et al. (2012) Comparison of MRI and ยน?F-NaF PET/CT in patients with patellofemoral pain. J Magn Reson Imaging 36:928-32
Steele, Katherine M; Demers, Matthew S; Schwartz, Michael H et al. (2012) Compressive tibiofemoral force during crouch gait. Gait Posture 35:556-60
John, Chand T; Seth, Ajay; Schwartz, Michael H et al. (2012) Contributions of muscles to mediolateral ground reaction force over a range of walking speeds. J Biomech 45:2438-43

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