Elevated vacuum socket suspensions are regularly used by trans-tibial amputees to secure the prostheses to the residual limb via externally applied vacuum. This suspension system has demonstrated unique health benefits for the limb and improved gait symmetry.
Published research on elevated vacuum socket suspension principally examines patient outcomes and pressure measurements. Aims of this dissertation were to investigate the effects of vacuum levels on various gait parameters. Three stand-alone papers describe (1) temporal and kinematic effects of vacuum levels, (2) kinetics and ground reaction force effects of vacuum levels and (3) amputee gait with the elevated vacuum socket suspension relative to able-bodied gait.
Nine male unilateral trans-tibial amputees with elevated vacuum socket suspension and nine able-bodied subjects participated in the study. Three-dimensional motion data were captured using a video camera and force plate system in conjunction with a reflective marker set. Able-bodied subjects walked at self-preferred walking speeds. Amputees walked at self-preferred walking speeds with typical vacuum levels for the first set of trials. Subsequent sets of trials were at a controlled walking speed with five randomized vacuum levels ranging from 0–20 inches Hg.
Comfort level improved with increasing vacuum (p=0.001). Step time asymmetry (p=0.035) and knee adduction moment ( p<0.05) values increased with vacuum. Several ground reaction force parameters had significant limb by vacuum interaction effects ( p<0.05). Limb effects typically had larger overall effect sizes than vacuum level and interaction effects. Intact limbs had greater values than residual limbs for stance phase duration (p=0.019), single support duration (p=0.008), step length ( p=0.005), walking speed (p<0.05), hip adduction moments (p<0.05), various ground reaction force parameters (p<0.05) and ankle joint power (p<0.001). Conversely, residual limbs had higher values for maximum lateral trunk obliquity (p=0.009) and hip and knee joint power impulses ( p<0.05). Control subjects had shorter double support phase ( p<0.05) than amputee subjects.
The intact limb of the amputee had a larger burden than the residual limb. Absence of plantar flexors in the residual limb induces between-limb differences and compensation mechanisms. At higher levels of vacuum amputees utilized the residual limb to a greater extent for some parameters, possibly due to increased socket comfort.
|Advisor:||Merryweather, Andrew S.|
|Commitee:||Bamberg, Stacy Morris, Bloswick, Donald S., MacWilliams, Bruce A., Martin, Jim|
|School:||The University of Utah|
|School Location:||United States -- Utah|
|Source:||DAI-B 73/07(E), Dissertation Abstracts International|
|Keywords:||Amputees, Biomechanics, Gait, Prosthetics, Vacuum socket suspension|
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