Dynamic Threshold Model of Spasticity that Can Predict Various Pendulum Motions

다양한 진자운동을 재현가능한 경직의 동적 역치 모델

  • 김철승 (건국대학교 일반대학원 의공학과) ;
  • 공세진 (건국대학교 일반대학원 의공학과) ;
  • 권선덕 (건국대학교 의과대학 재활의학과) ;
  • 김종문 (건국대학교 의과대학 재활의학과) ;
  • 엄광문 (건국대학교 의공학부, 건국대학교 의공학실용연구소)
  • Published : 2006.07.01

Abstract

The objective of this work is to develop the knee joint model for representing various pendulum motions and quantifying the spasticity. Knee joint model included the extension and flexion muscles. The joint moment consists of both the active moment from the stretch reflex and the passive moment from the viscoelastic joint properties. The stretch reflex was modeled as nonlinear feedback of muscle length and the muscle lengthening velocity, which is Physiologically-feasible. Moreover, we modeled the spastic reflex as having dynamic threshold to account far the various pendulum trajectories of spastic patients. We determined the model parameters of three patients who showed different pendulum trajectories through minimization of error between experimental and simulated trajectories. The simulated joint trajectories closely matched with the experimental ones, which show the proposed model can predict pendulum motions of patients with different spastic severities. The predicted muscle force from spastic reflex appeared more frequently in the severe spastic patient, which indicates the dynamic threshold relaxes slowly in this patient as is manifested by the variation coefficient of dynamic threshold. The proposed method provides prediction of muscle force and intuitive and objective evaluation of spasticity and it is expected to be useful in quantitative assessment of spasticity.

Keywords

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