Gait Analysis of Transfemoral Amputees: Errors in Inverse Dynamics Are Substantial and Depend on Prosthetic Design

Abstract

To cite this version:Raphaël Dumas, Rickard Brånemark, Laurent Frossard. Gait analysis of transfemoral amputees: errors in inverse dynamics are substantial and depend on prosthetic design. IEEE Transactions on Neural Systems and Rehabilitation Engineering, Institute of Electrical and Electronics Engineers, 2017, 25 (6), pp.679-685. <10.1109/TNSRE.2016.2601378>. <hal-01576284> 1  Abstract-Quantitative assessments of prostheses performances rely more and more frequently on gait analysis focusing on prosthetic knee joint forces and moments computed by inverse dynamics. However, this method is prone to errors, as demonstrated in comparison with direct measurements of these forces and moments. The magnitude of errors reported in the literature seems to vary depending on prosthetic components. Therefore, the purposes of this study were (A) to quantify and compare the magnitude of errors in knee joint forces and moments obtained with inverse dynamics and direct measurements on ten participants with transfemoral amputation during walking and (B) to investigate if these errors can be characterised for different prosthetic knees.Knee joint forces and moments computed by inverse dynamics presented substantial errors, especially during the swing phase of gait. Indeed, the median errors in percentage of the moment magnitude were 4% and 26% in extension/flexion, 6% and 19% in adduction/abduction as well as 14% and 27% in internal/external rotation during stance and swing phase, respectively. Moreover, errors varied depending on the prosthetic limb fitted with mechanical or microprocessorcontrolled knees.This study confirmed that inverse dynamics should be used cautiously while performing gait analysis of amputees. Alternatively, direct measurements of joint forces and moments could be relevant for mechanical characterising of components and alignments of prosthetic limbs.

Kinetics of Lower Limb Prosthesis: Automated Detection of Vertical Loading Rate

“…The loading profile can be calculated using inverse dynamics equations, providing the comprehensive dynamics and kinematics information responsible for the prosthetic and sound ankle, knee and hip joint kinetics [18][19][20][21][22][23][24][25]. However, this method relies on fixed equipment placed in delimited space.…”

“…Ground reaction forces are collected using floor-mounted force-plates in walkways, stairs or ramps. Positions of lower limb segments within a calibrated volume are captured using 3D motion analysis systems [18,19,26,27]. Valid dynamic measurements require sole contact of each foot on a force-plate that could be achieved through individualized arrangements of the starting point and/or force-plate positioning to avoid targeting and/or repetitive recording of invalid trials [18][19][20].…”

“…Positions of lower limb segments within a calibrated volume are captured using 3D motion analysis systems [18,19,26,27]. Valid dynamic measurements require sole contact of each foot on a force-plate that could be achieved through individualized arrangements of the starting point and/or force-plate positioning to avoid targeting and/or repetitive recording of invalid trials [18][19][20]. The sum of steps to be collected in a session is conditioned by the number and arrangement of force-plates and cameras [18][19][20].…”

“…Valid dynamic measurements require sole contact of each foot on a force-plate that could be achieved through individualized arrangements of the starting point and/or force-plate positioning to avoid targeting and/or repetitive recording of invalid trials [18][19][20]. The sum of steps to be collected in a session is conditioned by the number and arrangement of force-plates and cameras [18][19][20]. Otherwise, shortcomings with foot placement and the number of steps could be alleviated by using an instrumented treadmill, provided that 3D motion capture has the capacity to record for an extended period of time.…”

“…In addition to being resource intensive, the extraction of the loading profile using this approach is, altogether, partially reflective of the true prosthetic loading regimen applied during daily ambulation [18,19]. Therefore, evidence provided in this way, showing the effects of an intervention, has limited applicability.…”