Modelling of human walking to optimise the function of ankle-foot orthosis in Guillan-Barr, patients with drop foot

Jamshidi N, Rostami M, Najarian S, Menhaj MB, Saadatnia M, Firooz S
Correspondence: Dr Mostafa Rostami, nima_jamshidi@yahoo.com

ABSTRACT
Introduction This paper deals with the dynamic modelling of human walking. The main focus of this research was to optimise the function of the orthosis in patients with neuropathic feet, based on the kinematics data from different categories of neuropathic patients.
Methods The patient’s body on the sagittal plane was modelled for calculating the torques generated in joints. The kinematics data required for mathematical modelling of the patients were obtained from the films of patients captured by high speed camera, and then the films were analysed through a motion analysis software. An inverse dynamic model was used for estimating the spring coefficient.
Results In our dynamic model, the role of muscles was substituted by adding a spring-damper between the shank and ankle that could compensate for their weakness by designing ankle-foot orthoses based on the kinematics data obtained from the patients. The torque generated in the ankle was varied by changing the spring constant. Therefore, it was possible to decrease the torque generated in muscles which could lead to the design of more comfortable and efficient orthoses.
Conclusion In this research, unlike previous research activities, instead of studying the abnormal gait or modelling the ankle-foot orthosis separately, the function of the ankle-foot orthosis on the abnormal gait has been quantitatively improved through a correction of the torque.

Keywords: ankle-foot orthosis, gait analysis, Guillan-Barré syndrome, steppage gait
Singapore Med J 2009; 50(4): 412-417