The biomechanical response of persons with transfemoral amputation to variations in prosthetic knee alignment during level walking

Abstract

Prosthetic alignment is an important factor in the overall fit and performance of a lower-limb prosthesis. However, the association between prosthetic alignment and control strategies used by persons with transfemoral amputation to coordinate the movement of a passive prosthetic knee is poorly understood. This study investigated the biomechanical response of persons with transfemoral amputation to systematic perturbations in knee joint alignment during a level walking task. Quantitative gait data were collected for three alignment conditions: bench alignment, 2 cm anterior knee translation (ANT), and 2 cm posterior knee translation (POST). In response to a Participation Follow-Up: The authors do not plan to inform participants of the publication of this study. However, participants have been encouraged to check the Northwestern University Prosthetics-Orthotics Center Web site for updated publications related to the program's activities, which include the present study. Disclaimer:The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of the VA or the U.S. Government. U.S. Department of Veterans AffairsPublic Access Author manuscript J Rehabil Res Dev. Author manuscript; available in PMC 2017 August 17. VA Author ManuscriptVA Author Manuscript VA Author Manuscript destabilizing alignment perturbation (ANT), subjects significantly increased their early-stance hip extension moment, confirming that persons with transfemoral amputation rely on a hip extensor strategy to maintain knee joint stability. However, subjects also decreased the rate at which they loaded their prosthesis, decreased their step length, increased their trunk flexion, and maintained their limb in a more vertical posture at the time of opposite toe off. Collectively, these results suggest that persons with transfemoral amputation rely on a combination of strategies to coordinate stance-phase knee flexion. Further, no significant changes were observed in response to the POST condition, suggesting that a bias toward posterior alignment may have fewer implications in terms of stance-phase, knee-joint control.

An Extensive Set of Kinematic and Kinetic Data for Individuals with Intact Limbs and Transfemoral Prosthesis Users

“…For the prosthesis user, the standard deviations of joint angles and joint torques were greater than those of the subject with intact legs (AB04). The standard deviation of the vertical GRF is similar for both the prosthesis user and the subject with intact legs, but the average vertical GRF of the subject with intact legs is greater than that of the prosthesis user, which agrees with previous observations that prosthesis users place more weight on their intact side than on their prosthesis Koehler-McNicholas et al [ 26 ]. That is, the maximum vertical GRF in the mid-stance phase is 930 N for the subject with intact limbs, but only 815 N for the transfemoral prosthesis user.…”

Comparative biomechanical evaluation of two technologically different microprocessor-controlled prosthetic knee joints in safety-relevant daily-life situations

“…Prosthetic alignment next to functioning of the prosthetic knee joint has a significant influence on the biomechanical performance of a prosthesis [33,34]. In order to attribute functional differences of the knee joints exclusively to their properties, an identical prosthetic alignment is mandatory for comparative biomechanical studies.…”

Sockets for Limb Prostheses: A Review of Existing Technologies and Open Challenges

“…Schmalz et al [25] verified that an increased energy expenditure is required in case of a wrong alignment and this effect results more significant for transfemoral amputees, than for transtibial ones. Furthermore, it has been found that a wrong alignment in transfemoral amputees, causes an increased hip extension moment during the early stance phase, trunk flexion, a decreased step length and other undesired biomechanical effects [37].…”