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 rehabilitationStep 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; elevated vacuum; motion analysis; prosthesis; prosthetic foot; prosthetic limb; prosthetic suspension system; rehabilitation; virtual reality.