TY - GEN
T1 - Development of a motorized device for quantitative investigation of articulated AFO misalignment
AU - Gao, Fan
AU - Carlton, William
AU - Kapp, Susan
PY - 2010
Y1 - 2010
N2 - the objective of the study is to develop a motorized device to quantitatively investigate the AFO alignment and mechanical properties. The motorized device consists of a servo motor and an inline gear box with a 25:1 gear ratio. A thermoplastic articulated AFO with Tamarack dorsiflexion assist flexure joint was investigated in the study. The motor shaft was used to mimic the anatomical ankle joint. The joint of the AFO was aligned in such a way that the offset could be systematically manipulated (aligned exactly with the center of motor shaft, 10mm superior, inferior, anterior or posterior with respect to the center of motor shaft). The AFO was passively moved in the range from 30° plantar flexion to 20° dorsiflexion at a prescribed speed of 3°/s. 11 complete cycles were run lasting about 400 s. Index of hysteresis was calculated as the ratio of area within the loop to the area below the ascending limb and presented in percentage (%). In addition, passive resistance torque and quasi-static stiffness were quantified at prescribed positions. Based on the preliminary results the perfect alignment will result in the lowest resistance torque, quasi-static stiffness and moderate hysteresis index. However, the alignment of 10 mm inferior showed the largest hysteresis index indicating an excessive energy loss during unloading phase and higher resistance torques during the loading phase. It suggested that alignment excessively below the anatomical joint should be avoided in clinical practice. The alignment of 10 mm superior showed comparable quantities to the perfect alignment and could be recommended in practice if perfect alignment is hard or not possible to implement. In summary, we have demonstrated that the device could be a powerful quantitative tool for practitioners and researchers. It is expected that the information obtained will be valuable to clinicians and provide recommendation on decision-making. In addition, the quantitative results will be useful in simulation and modeling studies.
AB - the objective of the study is to develop a motorized device to quantitatively investigate the AFO alignment and mechanical properties. The motorized device consists of a servo motor and an inline gear box with a 25:1 gear ratio. A thermoplastic articulated AFO with Tamarack dorsiflexion assist flexure joint was investigated in the study. The motor shaft was used to mimic the anatomical ankle joint. The joint of the AFO was aligned in such a way that the offset could be systematically manipulated (aligned exactly with the center of motor shaft, 10mm superior, inferior, anterior or posterior with respect to the center of motor shaft). The AFO was passively moved in the range from 30° plantar flexion to 20° dorsiflexion at a prescribed speed of 3°/s. 11 complete cycles were run lasting about 400 s. Index of hysteresis was calculated as the ratio of area within the loop to the area below the ascending limb and presented in percentage (%). In addition, passive resistance torque and quasi-static stiffness were quantified at prescribed positions. Based on the preliminary results the perfect alignment will result in the lowest resistance torque, quasi-static stiffness and moderate hysteresis index. However, the alignment of 10 mm inferior showed the largest hysteresis index indicating an excessive energy loss during unloading phase and higher resistance torques during the loading phase. It suggested that alignment excessively below the anatomical joint should be avoided in clinical practice. The alignment of 10 mm superior showed comparable quantities to the perfect alignment and could be recommended in practice if perfect alignment is hard or not possible to implement. In summary, we have demonstrated that the device could be a powerful quantitative tool for practitioners and researchers. It is expected that the information obtained will be valuable to clinicians and provide recommendation on decision-making. In addition, the quantitative results will be useful in simulation and modeling studies.
KW - AFO
KW - Dorsiflexion
KW - Hysteresis
KW - Plantarflexion
KW - Quasi-static stiffness
KW - Range of motion
KW - Resistance torque
UR - http://www.scopus.com/inward/record.url?scp=77956139501&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77956139501&partnerID=8YFLogxK
U2 - 10.1109/ICBBE.2010.5514982
DO - 10.1109/ICBBE.2010.5514982
M3 - Conference contribution
AN - SCOPUS:77956139501
SN - 9781424447138
T3 - 2010 4th International Conference on Bioinformatics and Biomedical Engineering, iCBBE 2010
BT - 2010 4th International Conference on Bioinformatics and Biomedical Engineering, iCBBE 2010
T2 - 4th International Conference on Bioinformatics and Biomedical Engineering, iCBBE 2010
Y2 - 18 June 2010 through 20 June 2010
ER -