Biomedical subjects

L M Schutte

Publications and source records attributed to L M Schutte.

3 recordsLinked to original sources

PubMed2000

An index for quantifying deviations from normal gait.

A method is derived to calculate the amount by which a subject's gait deviates from an average normal profile, and to represent this deviation as a single number. The method uses principal component analysis to derive a set of 16 independent variables from 16 selected gait variables. The sum of the square of these 16 independent variables is interpreted as the deviation of the subject's gait from normal. Statistical tests of the method's validity and an initial demonstration of its clinical utility are included. It is found that using this index, increasing clinical involvement corresponds to increasing index score.

Adolescent↗

PubMed1997

Lengths of hamstrings and psoas muscles during crouch gait: effects of femoral anteversion.

Recent studies of muscle lengths measured by means of gait analysis data and musculoskeletal models have suggested that in many cases of crouch gait in patients with cerebral palsy, the hamstrings are of normal length and the psoas muscles are short. In these studies, however muscle lengths were calculated by applying kinematic data from a child's joint to a normal adult model. Children with cerebral palsy and other disorders generally do not have normal bone architecture but instead have muscle attachment points and muscle paths altered by osseous deformities. In this study, we explored the consequences of using normal adult musculoskeletal models to calculate hamstring and psoas lengths for children with cerebral palsy. Specifically, for a group of subjects with cerebral palsy who walk with a crouch gait, we investigated the changes in muscle lengths that arise when a patient-specific representation of clinically measured femoral anteversion was added to a model of normal musculoskeletal geometry. The calculation of psoas muscle length was found to be very sensitive to femoral anteversion whereas the calculation of hamstrings length was found to be relatively insensitive to this osseous deformity.

Adolescent↗

PubMed1997

The use of inverse dynamics solutions in direct dynamics simulations.

Previous attempts to use inverse dynamics solutions in direct dynamics simulations have failed to replicate the input data of the inverse dynamics problem. Measurement and derivative estimation error, different inverse dynamics and direct dynamics models, and numerical integration error have all been suggested as possible causes of inverse dynamics simulation failure. However, using a biomechanical model of the type typically used in gait analysis applications for inverse dynamics calculations of joint moments, we produce a direct dynamics simulation that exactly matches the measured movement pattern used as input to the inverse dynamic problem. This example of successful inverse dynamics simulation demonstrates that although different inverse dynamics and direct dynamics models may lead to inverse dynamics simulation failure, measurement and derivative estimation error do not. In addition, inverse dynamics simulation failure due to numerical integration errors can be avoided. Further, we demonstrate that insufficient control signal dimensionality (i.e., freedom of the control signals to take on different "shapes"), a previously unrecognized cause of inverse dynamics simulation failure, will cause inverse dynamics simulation failure even with a perfect model and perfect data, regardless of sampling frequency.

Biomechanical Phenomena↗