Document Type : Full Research Paper


1 M.Sc., Department of Biomechanics, Department of Biomedical Engineering, Sahand University of Technology, Tabriz, Iran

2 Assistant Professor, Department of Biomechanics, Department of Biomedical Engineering, Sahand University of Technology, Tabriz, Iran

3 Assistant Professor, Department of Rehabilitation, Isfahan University of Medical Sciences, Isfahan, Iran



Balance in daily movements like as stair ascending is a challenge for the people with leg lengths discrepancy (LLD). These people change their pattern of movement to compensate the difference between legs’ length. Due to the changes in movement pattern, body's center of mass which is one of the important factors in maintaining balance can be varied.  Compensatory insoles are used to compensate for short legs. The aim of this study is to investigate changes in the center of mass, with and without using insoles in people with leg length discrepancy when climbing stairs. In this practical cross-sectional study, the movement of 20 participants while climbing stairs in two groups of healthy people and people with LLD was recorded by a three-dimensional movement analysis system. Changes in pelvic, knee and ankle joint angles were calculated with the 7-member Euler method. Then the rotation and transferring matrixes were defined by using the joint angles to determine the torque arm of the limbs.  By the total body torque method, the center of mass changes in three directions were obtained. Then, these changes were compared between the experimental and control groups using independent and paired t-test at 95% confidence level. The results showed that the displacement of the center of mass in all three directions was significantly higher for people with different leg length differences when comparing with healthy people (p<0.05). The results also showed that range of movement has no significant different in the Vertical axis between normal and LLD people (p>0.05) when using insole. Based on the findings of this study, it can be concluded that the use of compensatory insoles alone cannot make changes in the center of mass as one of the indicators to measure the balance in climbing stairs like normal people.


Main Subjects

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