Transtibial amputee gait with the unity suspension system

Abstract

Study Design: Experimental study.

Objectives: Research is lacking on the Unity suspension system’s effect on gait performance. The purpose of this study was to evaluate the effects of the Unity elevated vacuum system on level walking performance while the vacuum was active (ON) and inactive (OFF).

Methods: Twelve unilateral transtibial amputees were fit with the Ossur elevated vacuum suspension system (Unity) and Pro-flex XC foot. After one month accommodation period, 3D motion analysis was performed using the CAREN-Extended system. Temporal-spatial, kinematics, and kinetics were examined during level walking to understand the effect of the elevated vacuum, separate trials were completed with the vacuum active (ON) or inactive (OFF).

Results: Significant differences were found between vacuum conditions (ON and OFF) for some temporal-spatial gait parameters, but differences were very small and may not be clinically significant. Differences between vacuum conditions on most kinetic and kinematic gait parameters were also low. However, step length symmetry between intact and prosthetic limbs improved with active elevated vacuum (ON).

Conclusions: Elevated vacuum suspension’s effect on level walking gait is small if a well-fitting liner-based socket is provided.

Implications for rehabilitation

• Step length symmetry between intact and prosthetic limbs improved with an active vacuum system.

• Differences between vacuum conditions on most gait parameters were small during level walking.

• Subjective feedback showed improved proprioception and comfort with an active vacuum system.

Keywords:

• Amputation
• prosthetic limb
• elevated vacuum
• prosthesis
• prosthetic suspension system
• motion analysis
• rehabilitation
• prosthetic foot
• virtual reality

Acknowledgements

The authors would like to thank Knut Lechler, Kristleifur Kristjansson, þorvaldur Ingvarsson, Nancy Dudek, for providing clinical and technical advice and support. Courtney Bridgewater, Andrew Smith, Andrew Herbert-Copley, and Gabrielle Thibault are thanked for assistance with clinical testing and analyzing the data.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This study was financially supported by Mitacs and Össur. All prosthetics components were provided by Össur. Also financial support was received from Mitacs.