SUBJECT-SPECIFIC MUSCULOSKELETAL MODELING OF THE LOWER EXTREMITIES IN PERSONS WITH UNILATERAL CEREBRAL PALSY by

The computational musculoskeletal models that are used to study muscle momentgenerating capacities of persons with movement disorders and planning treatment options must be accurate, and take into account the inter-individual variability of musculoskeletal geometry. In Paper I the methods of creating the subject-specific musculoskeletal model of the lower extremities from magnetic resonance images (MRIs) were developed. The subject-specific model was used to analyze hip, knee and ankle muscle moment arms (MALs) and muscletendon lengths (MTLs) during gait in a subject with unilateral cerebral palsy (CP), and to evaluate the accuracy of widespread and commonly-used scaled generic model. It was found that the scaled generic model delivered accurate values for changes in MTLs in most muscles. However, the scaled generic and the subject-specific lower extremity musculoskeletal models showed substantial differences in MALs calculated during gait. In Paper II subject-specific musculoskeletal models of nine subjects with unilateral CP were created to study muscles volumes, MTLs and MALs; and to examine the accuracy of MALs calculated by the scaled generic models. It was shown that the scaled generic model significantly underestimated hip MALs discrepancies between the affected and the non-affected sides of the lower extremities. However, it significantly overestimated hip adduction/abduction of gluteus maximus, gluteus medius, gluteus minimus, tensor fascia latae and biceps femoris long head; and hip flexion of adductor longus and rectus femoris in the affected and the non-affected sides.