The dynamic model of the thumb and index finger - Rehabilitation Institute of Chicago

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Fri, Apr 29

Speaker: Dan Qiu (Dr. Kamper's group)

Title: The dynamic model of the thumb and index finger

Abstract:   The thumb and finger movement disabilities are common in stroke survivors. Flexor spasticity, muscle atrophy and excessive flexor-extensor co-activation may all contribute to the defective hand capacity. The extent to which each potential mechanism contributes to motor impairment may be difficult to discern. Separating the effect of each factor would help the therapist understand the specific status of the patients and select appropriate recovery strategies. The index finger and the thumb biomechanical models would help to increase our understanding about the hand performance and the undergoing muscle activities.

The dynamic model of the thumb and index finger in this study is designed to model the transformation of muscle activations into thumb and index finger movement, describing muscle activation dynamics, contraction dynamics and force transmission.  Force-based approaches are employed to represent the interactions between tendons and finger segments, which reflect the realistic force transformation mechanism of muscle tendon structures. Most of model parameters, such as muscle lengths, tendon slack lengths and muscle anatomical pulley positions are measured on specimens.  Joint passive properties are measured in vivo with a device designed to supply perturbation independently to each of the finger joints. Model will be validated with cadaver and human subject experiments. The model is constructed with Simulink SimMechanics toolbox.

This model has been used to simulate the index finger isometric force generation at the fingertip and movement under certain muscle loading patterns. The predicted results were compared with in vivo stimulated experiment. The predicted force directions were compared with the results of muscle stimulation experiments performed in vivo with human subjects.