title: 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 destabilizing alignment perturbation (i.e., the ANT condition), participants 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, participants also decreased the rate at which they loaded their prosthesis, decreased their affected-side step length, increased their trunk flexion, and maintained their prosthesis 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, comparatively few 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.
authors.affiliation: Northwestern University Prosthetics-Orthotics Center, Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL.|Jesse Brown VA Medical Center, Chicago, IL.
authors.forename: Sara R
authors.initials: SR
authors.lastname: Koehler-McNicholas
authors.affiliation: Northwestern University Prosthetics-Orthotics Center, Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL.|Rehabilitation Institute of Chicago, Chicago, IL.
authors.forename: Robert D
authors.initials: RD
authors.lastname: Lipschutz
authors.affiliation: Northwestern University Prosthetics-Orthotics Center, Department of Physical Medicine and Rehabilitation, Feinberg School of Medicine, Northwestern University, Chicago, IL.|Jesse Brown VA Medical Center, Chicago, IL.
authors.forename: Steven A
authors.initials: SA
authors.lastname: Gard
mesh_terms: D000328:Adult; D000671:Amputation, Surgical; D000674:Amputees; D001186:Artificial Limbs; D001696:Biomechanical Phenomena; D018592:Cross-Over Studies; D005260:Female; D005684:Gait; D006801:Humans; D007717:Knee; D007719:Knee Joint; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011187:Posture; D017755:Prosthesis Fitting; D016138:Walking / Q000502:physiology*; D055815:Young Adult
keywords: alignment; amputee; artificial limbs; gait analysis; hip; knee; load cell; transfemoral; treadmill; trunk