The evidence-base for elevated vacuum in lower limb prosthetics: Literature review and professional feedback

Gholizadeh, Hossein; Lemaire, Edward D.; Eshraghi, Arezoo

doi:10.1016/j.clinbiomech.2016.06.005

Cited by 43 publications

(49 citation statements)

References 36 publications

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“…Literature has shown that donning and doffing the prosthesis is challenging for elderly amputees using Seal-In X5 liner. 2,22 This study showed that a minimum of 151±15N was needed with the PETG conical socket and standard profile liner in open valve condition to pull off the socket, and a maximum of 748±291N was needed for the Thermolyne soft socket. Therefore, PETG would be good choice for amputees who may have difficulty doffing their prosthesis.…”

Section: Mechanical Evaluation Of öSsur Unity Suspension Systemmentioning

confidence: 86%

“…A standard lock system for all amputees has not been defined. 1,2,6 system to decrease pistoning within the socket, reduce residual limb volume loss over time, and improve prosthesis control and proprioception. 1,3,9,10 Street 11 mentioned that vacuum could eliminate movement and reduce shear, provide a healthier environment for the residual limb, and prevent volume loss.…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Evaluation of Unity Elevated Vacuum Suspension System

Gholizadeh

Lemaire

Salekrostam

2020

Can. Prosthet. Orthot. J.

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BACKGROUND: Small residual limb-socket displacement is a good indicator of prosthetic suspensionsystem quality. Active vacuum suspension systems can decrease vertical movement inside the socket,compared to non-active suction systems. This study mechanically evaluated limb-socket displacementwith the Össur Unity active vacuum system. METHOD: Forty-eight conditions were evaluated: four cylindrical and four conical sockets(polypropylene, polyethylene terephthalate glycol-modified (PETG), thermoset resin (acrylic),Thermolyn soft materials); two Iceross Seal-In V liners (standard, high profile); three vacuumconditions (active vacuum, inactive vacuum, no suction with valve open). An Instron 4428 test machineapplied 0-100N linear ramped tensile loads to each positive mold, with the socket secured in place,while displacement between the mold and socket was recorded. Following the displacement tests, theload before failure (i.e., 10 mm displacement) was measured. RESULTS: Average and standard deviations for movement between the mold and sockets were small.The displacement average for all conditions was 0.30±0.16mm for active vacuum, 0.32±0.16mm forinactive vacuum, and 0.39±0.22mm for no suction. Across all trials, active vacuum systems toleratedsignificantly (p<0.001) more load before failure (812±221N) compared to inactive vacuum (727±213N),and no suction (401±184N). The maximum load before failure (1142±53N) was for the cylindricalpolypropylene socket and high-profile liner. CONCLUSION: The Unity system successfully controlled pistoning inside the socket for regularactivity loads and also controlled the greatest traction loads. While relative movement was smallestfor Unity, all conditions (inactive vacuum, no suction) were viable for loads less than 100N.Furthermore, similar results can be achieved when using different socket fabrication materials. LAYMAN’S ABSTRACT: Prosthetic technology innovation is essential to enhance amputee's quality of life because amputation causes a permanent disability and people with limb loss rely on prostheses for the rest of their lives. The method for attaching a prosthesis to the body is termed prosthetic suspension. Selecting a suitable suspension system is an important step in the prosthetic rehabilitation process. Recently, the Unity elevated vacuum suspension system (https://assets.ossur.com/library/31882/IFU) was developed by Össur. Understanding of how the Unity elevated vacuum system controls limb movement within the socket, with different socket materials, is important to guide prosthetic prescription. Therefore, mechanical testing was conducted to provide quantitative evidence to guide clinical practice. This study showed that the Unity system can hold the residual limb inside the socket successfully even if there is a failure in the vacuum pump. Elevated vacuum made the socket harder to pull off, which is beneficial in cases where the prosthetic foot is snagged during movement. Article PDF Link: https://jps.library.utoronto.ca/index.php/cpoj/article/view/32941/25960 How to Cite: Gholizadeh H, Lemaire ED, Salekrostam R. Mechanical evaluation of unity elevated vacuum suspension system. Canadian Prosthetics & Orthotics Journal. 2019;Volume2, Issue2, No.5. https://doi.org/10.33137/cpoj.v2i2.32941 *CORRESPONDING AUTHORHossein Gholizadeh,BSc (P&O), MEng.Sc, PhD,Ottawa Hospital Research Institute, Centre for Rehabilitation Research and Development, Ottawa, Canada.Email: gholizadeh87@yahoo.comORCID: https://orcid.org/0000-0001-5847-7985

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Section: Mechanical Evaluation Of öSsur Unity Suspension Systemmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Mechanical Evaluation of Unity Elevated Vacuum Suspension System

Gholizadeh

Lemaire

Salekrostam

2020

Can. Prosthet. Orthot. J.

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“…Based on the literature [ 2 , 5 – 7 ], vacuum assisted suspension system (VASS) could improve prosthetic function, comfort, satisfaction, and quality of life compared to other prosthetic suspension systems on the market such as single distal pin/lock, lanyard, suction, or Kondylen Bettung Munster (KBM) suspension system. Board et al demonstrated that step length and stance time were more asymmetric when walking with inactive vacuum (suction suspension) compared to active vacuum suspension [ 2 ].…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, VASS may not be appropriate for all amputees because more attention and skills are needed for donning the liner, socket, and sleeve. Moreover, an external sleeve (i.e., suspension and vacuum seal layer) that covers the socket, knee, and lower thigh can limit knee range of motion [ 5 ]. The Unity elevated vacuum suspension system (Össur) was developed to address these limitations.…”

Section: Introductionmentioning

confidence: 99%

Effects of the unity vacuum suspension system on transtibial gait for simulated non-level surfaces

Thibault¹,

Gholizadeh²,

Sinitski³

et al. 2018

PLoS ONE

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Walking on various surfaces encountered in everyday life requires lower limb prosthesis users to continually adapt their movement patterns. Elevated vacuum suspension systems could improve transtibial amputee gait on non-level surfaces; however, research is lacking to guide clinical practice. Twelve transtibial amputees were fitted with the Össur sleeveless vacuum suspension system (Unity). After a one month accommodation period, the CAREN-Extended system was used to evaluate gait on a self-paced treadmill when walking with continuous perturbations (medial-lateral translations, rolling hills, simulated uneven ground) with an active or inactive vacuum suspension system. Significant differences between active and inactive vacuum conditions (p<0.05) were found for some temporal-spatial and kinematic gait parameters, but the differences were small and not considered clinically significant. Our findings suggest that potential vacuum pump failures would not immediately affect gait performance in a moderately high functioning amputee population. However, residual limb volume changes over time due to the removal of elevated vacuum may adversely affect socket fit, leading to greater gait differences and reduced quality of life.

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“…In fact, several studies have found that elevated vacuum systems do not preclude wound healing, and allow patients to ambulate sooner and for longer periods of time compared to other systems [ 19 – 21 ]. Generally, elevated vacuum systems are viewed favourably by clinicians, however questionnaire results have shown that they are perceived as being “more expensive, heavier, less durable, and require more maintenance” than a standard socket [ 22 ]. Several review articles have been published in this area, and while existing evidence for elevated vacuum systems is promising, these reviews have indicated a need for more controlled studies, larger sample sizes, and evaluation of long-term effects [ 6 , 22 – 24 ].…”

Section: Introductionmentioning

confidence: 99%

Real time monitoring of transtibial elevated vacuum prostheses: A case series on socket air pressure

Schoepp

Schofield²,

Home

et al. 2018

PLoS ONE

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Prosthetic elevated vacuum is a suspension method used to reduce daily volume changes of the residual limb. Evaluation of the effectiveness of these systems is limited due to a lack of correlation to actual socket air pressure, particularly during unconstrained movements. This may explain some of the variability in functional outcomes reported in the literature. Our objective was to develop a light-weight portable socket measurement system to quantify internal socket air pressure, temperature, and acceleration; and to present preliminary results from implementation with three transtibial prosthesis users with mechanical elevated vacuum pumps. Participants completed five functional tasks with and without the vacuum pumps actively connected, including the 2-Minute Walk test, 5-Times Sit-to-Stand test, 4-Square Step test, L-Test, and Figure-8 test. Results demonstrated different gait profiles and pressure ranges for each user. Two of the participants demonstrated substantially lower air pressure (higher vacuum) over time while the pump was active compared to inactive. The minimum air pressure measured for all participants was -34.6 ± 7.7 kPa. One participant did not show substantial changes in pressure over time for either pump condition. Functional task performance was not significantly different between pump conditions. Correlation with accelerometer readings indicated peak positive pressures occurred just following initial contact of the foot in early stance, and the most negative pressures (highest vacuum) were observed throughout swing. This study has demonstrated the use of a portable data logging tool that may serve the clinical and research communities to quantify the operation of elevated vacuum systems, and better understand the variability of mechanical pump operation and overall system performance.

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The evidence-base for elevated vacuum in lower limb prosthetics: Literature review and professional feedback

Cited by 43 publications

References 36 publications

Mechanical Evaluation of Unity Elevated Vacuum Suspension System

Mechanical Evaluation of Unity Elevated Vacuum Suspension System

Effects of the unity vacuum suspension system on transtibial gait for simulated non-level surfaces

Real time monitoring of transtibial elevated vacuum prostheses: A case series on socket air pressure

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