Biomechanical Analysis of the Influence of SACH Foot and Dynamic-Response Foot in Individual With Unilateral Transtibial Amputee During Running

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Objective: Amputation of the lower limb due to loss of part of the musculoskeletal structure reduces performance and increases injury during locomotion. The effect of various types of prosthetic feet has been analyzed in several studies during running. The purpose of this study was a biomechanical analysis of the influence of SACH and Dynamic-Response foot on several kinetic variables in the stance phase of running in individuals with unilateral transtibial amputation. Materials & Methods: In this semi-experimental study, 8 left foot transtibial amputees were included in this study using an available or easy sampling method. The target population was unilateral transtibial amputees who were able to run and the available population included left transtibial amputees who were referred to Kosar Rehabilitation Center in Tehran from 2008 to 2012. To adapt to the foot, each foot was used by the subjects for at least one week before the experiment. All subjects participated in 3 running evaluation sessions; 1 session involving the use of their own foot (familiarization session), 1 session involving the use of SACH foot, and 1 session involving the use of Dynamic foot. Only data from the 2 last sessions were used to compare both feet. Each subject runs in 12-meter walkway 3 times at a speed of 2.5 meters per second. The same running speed was chosen for the comparability of kinetic variables. Sport shoes were used to bring the test conditions closer to the actual running conditions. In each session, 3 successful trials were performed so that the foot was in full and perfect contact with the force plate. Kistler force plate and three-dimensional motion analysis Vicon system were used to collect kinetic and kinematic data, respectively. The motion and the force plate data were sampled simultaneously at 200 and 1000 Hz, respectively. The trajectories of the markers and analog data were filtered using the predicted mean square error adaptive filter in version 1.7 of the Vicon software package. The Kinetic variables were generated using the dynamic model of the Vicon Plug-in-Gait. The vertical ground reaction force was normalized for body weight. In the present study, 5 variables were selected for biomechanical analysis of feet. The maximum vertical ground reaction force, power, spring efficiency, ankle moments at the amputated leg, and the symmetry ratio (percentage) of the maximum vertical ground reaction force between the amputated leg and the intact leg were calculated. All values ​​in each trial were averaged for each subject with each foot. A paired t-test and a Wilcoxon test were used to analyze the data based on normality (P ≤0.05). Results: In examining the normality of the data distribution, the results showed that the data of maximum power absorption of the ankle with the SACH foot and the maximum power absorption of the hip with the Dynamic-Response foot did not have a normal distribution and other variables had a normal distribution. The results of paired t-test and Wilcoxon showed that Spring Efficiency and Maximum Plantar Flexion were significantly different between the SACH and Dynamic-Response feet (P ≤0.05). The Spring Efficiency was greater with Dynamic-Response foot than the SACH foot (P =0.05), although the Maximum Plantar Flexion with the SACH foot was greater than Dynamic-Response foot (P =0.05). While there is no statistical difference between the maximum vertical ground reaction force, maximum power absorption and generation in the ankle, maximum power absorption and generation in the knee, maximum power absorption and generation in the hip, maximum dorsiflexion moment, and the symmetry ratio (percentage) of the maximum vertical ground reaction force between the amputated leg and the intact leg. Conclusion: The results of the study showed that the spring efficiency with Dynamic-Response foot was greater than SACH foot and closing to the spring efficiency of a normal foot. With this perspective, the Dynamic-Response foot has more natural performance than the SACH foot.