Vacuum Suspension: Effects on Tissue Oxygenation, Activity and Fit

• Sponsor: US Department of Veterans Affairs (U.S. Fed)
• Overall Status: Completed
• CT.gov ID: NCT00117793
• Collaborator: (none)
• Enrollment: 20
• Location: 1
• Arms: 2
• Duration (Months): 37
• Patients Per Site Per Month: 0.5

Study Details

Study Description

Brief Summary

The fit of the residual limb within a prosthetic socket is a primary concern for many amputees. A poor fit can lead to skin irritation, tissue breakdown, and pain. Further, amputees with diabetes or vascular dysfunction often have difficulty maintaining healthy residual limb tissue; a condition that could be mitigated by the application of negative pressure (i.e., vacuum suspension). The aim of this research is to characterize the residual limb response to a vacuum suspension system and to measure prosthetic performance in comparison to a typical suction suspension system.

The proposed research plan involves two sets of human subject experiments: (1) prospective, randomized cross-over study to quantify performance of a vacuum suspension system as compared to a total surface bearing suction socket in terms of pistoning, maintaining limb volume, step counts, and subjective measures of fit and (2) measurement of transcutaneous oxygen tension as a function of vacuum pressure.

Condition or Disease	Intervention/Treatment	Phase
Amputation; Diabetes; Leg Injuries; Traumatic Amputations	Device: Total Surface Bearing Suction Socket; Device: Vacuum assisted socket system	N/A

Detailed Description

A proper fitting prosthetic socket provides the amputee with a comfortable system allowing them to pursue many of their desired vocational and recreational goals. Unfortunately, many amputees live with an ill-fitting socket and can experience limb pistoning within the socket, which in turn may result in skin irritation, tissue breakdown, discomfort, and a reduction in activity. One of the key factors affecting fit is intraday residual limb volume changes. For an amputee with dysvascular conditions, the implications of a poor fitting socket are exacerbated by poor circulation, reduced healing potential and the compressive forces exerted by their prosthesis.

Vacuum suspension systems may have the potential to alleviate these conditions for healthy and dysvascular amputees. The purported benefits of vacuum suspension systems include, but are not limited to: improved suspension (reduction in the amount of pistoning), maintenance of limb volume throughout the day, and increased tissue oxygenation to the residual limb.

Our first objective is to characterize performance, as related to socket fit, of a vacuum suspension system using objective and subjective measures. We will do this by conducting a within-subject experiment to measure pistoning in three dimensions while walking, overall and regional changes in limb volume before and after a thirty-minute treadmill walk, mobility (step counts) and the perception of socket fit (questionnaire) as a function of prosthetic prescription (vacuum suspension system vs. total surface bearing suction socket).

Our second objective is to determine the effect of pressures within a prosthetic socket on residual limb transcutaneous oxygen tension (tcpO2) levels. We will conduct laboratory-based, in situ testing to determine how the transcutaneous oxygen tension levels, at six sites on the residual limb, respond to pressures simulating those within a vacuum suspension system and a total surface bearing suction socket.

The proposed research will allow us to understand how suspension systems influence prosthetic socket fit and residual limb tissue health and to formulate a knowledge base on two suspension systems providing prosthetists and clinicians the objective data to make better prescription decisions. In addition, the methods utilized in this study (e.g., a residual limb limb volume scanner and assessing dynamic pistoning) can be used to study current and novel suspension systems, liners, and prosthetic socket designs to provide a standard for comparison.

Study Design

• Study Type: Interventional
• Actual Enrollment: 20 participants
• Allocation: Randomized
• Intervention Model: Crossover Assignment
• Masking: Single (Participant)
• Primary Purpose: Treatment
• Official Title: Vacuum Suspension: Effects on Tissue Oxygenation, Activity and Fit
• Study Start Date: Aug 1, 2005
• Actual Primary Completion Date: Sep 1, 2008
• Actual Study Completion Date: Sep 1, 2008

Arms and Interventions

Arm	Intervention/Treatment
Active Comparator: Arm 1 Current clinical practice	Device: Total Surface Bearing Suction Socket; Current clinical practice
Experimental: Arm 2 Novel socket system	Device: Vacuum assisted socket system; Novel socket system

Outcome Measures

Primary Outcome Measures

1. Limb Volume [Measurements were taken after wearing the study prostheses for three weeks]

2. Activity Level [Two weeks]

   Total number of steps during a two week period ending in the fourth week for each study prosthesis (PIN and VASS).

3. Limb Pistoning [Measurements were taken after wearing the study prosthesis for three weeks]

   Limb pistoning is the change in the resultant distance between the prosthetic-side knee joint marker triad and the residual limb thigh triad measured using a 12-camera motion analysis system while subjects weighted and un-weighted their prosthesis standing in place.

Secondary Outcome Measures

1. Residual Limb Health (PEQ Scale) [Measurements were taken after wearing the study prosthesis for four weeks]

   Qualitative differences between the study limbs were assessed using the Prosthesis Evaluation Questionnaire (PEQ). This standardized, self-report instrument is specific to persons with lower limb amputations and is used to evaluate prosthetic care with regard to prescription and prosthesis-related quality of life. The Residual Limb Health scale examines: sweat, smell, volume changes, rashes, ingrown hairs, and blisters. The scale is scored from 0 to 100 where 100 indicates the best outcome (i.e., most healthful).

2. Ambulation (PEQ Scale) [Measurements were taken after wearing the study prosthesis for four weeks]

   Qualitative differences between the study limbs were assessed using the Prosthesis Evaluation Questionnaire (PEQ). This standardized, self-report instrument is specific to persons with lower limb amputations and is used to evaluate prosthetic care with regard to prescription and prosthesis-related quality of life. The Ambulation scale queries the ability to walk in general, in close spaces, on stairs and ramps, in urban environments, and on slippery surfaces. The scale is scored from 0 to 100 where 100 indicates the best outcome (i.e., easiest to walk on).

3. Frustration (PEQ Scale) [Measurements were taken after wearing the study prosthesis for four weeks]

   Qualitative differences between the study limbs were assessed using the Prosthesis Evaluation Questionnaire (PEQ). This standardized, self-report instrument is specific to persons with lower limb amputations and is used to evaluate prosthetic care with regard to prescription and prosthesis-related quality of life. Frustration was assessed by frequency of occurrence and rating. The scale is scored from 0 to 100 where 100 indicates the best outcome (i.e., least frustrating).

Eligibility Criteria

Criteria

• Ages Eligible for Study: 18 Years to 70 Years
• Sexes Eligible for Study: All
• Accepts Healthy Volunteers: Yes

Inclusion Criteria:

• Over 18 and less than 70 years of age,

• Have a below knee amputation involving only one side,

• If the cause of amputation was for traumatic reasons and do not have diabetes or a vascular condition, the amputation must have occurred at least six months ago and the potential subject must have worn a prosthesis for at least four months,

• If the cause of amputation was for diabetes or vascular reasons, the potential subject must have been fit with a prosthesis and have worn it for at least one year,

• Wear the prosthesis for at least 6 hours a day,

• Able to walk without a cane, crutches, or a walker,

• Are moderately active enough to walk at a steady pace for at least 30 minutes.

Exclusion Criteria:

• Have pain in legs or any condition that interferes with walking.

• Have an ulcer on the residual limb,

• If potential subject had an amputation because of a tumor or an infection, no longer have an active tumor or undergoing treatment for a tumor,

• Have fallen within the last 3 months.

Contacts and Locations

Locations

	Site	City	State	Country	Postal Code
1	VA Puget Sound Health Care System, Seattle	Seattle	Washington	United States	98108

Sponsors and Collaborators

• US Department of Veterans Affairs

Investigators

• Principal Investigator: Glenn K. Klute, PhD, VA Puget Sound Health Care System, Seattle

Study Documents (Full-Text)

None provided.

More Information

Publications

None provided.

• Responsible Party: US Department of Veterans Affairs
• ClinicalTrials.gov Identifier: NCT00117793
• Other Study ID Numbers: A3666
• First Posted: Jul 8, 2005
• Last Update Posted: Aug 15, 2014
• Last Verified: Jul 1, 2014

• Keywords provided by US Department of Veterans Affairs: Amputee; Artificial limbs; Gait; Walking
• Additional relevant MeSH terms: Amputation, Traumatic; Leg Injuries

Study Results

Participant Flow

Recruitment Details	Recruitment for this study was conducted at the VA Puget Sound Health Care System (Seattle VA hospital). Recruitment began on March 28, 2007. The study was closed to enrollment on March 30, 2012.
Pre-assignment Detail	The prostheses used in this study were built and aligned by a certified and licensed prosthetist prior to beginning starting the protocol. 20 individuals gave informed consent but 3 withdrew prior to starting: 1 had contralateral knee surgery, 1 became a bi-lateral amputee, and 1 was withdrawn by the participant's physician.

Arm/Group Title	Entire Study Population
Arm/Group Description	This is a randomized cross-over study. Each participant wore both study prostheses: (1) a total surface bearing socket with a vacuum-assisted suspension system (VASS) and (2) a modified patellar tendon bearing socket with a pin lock suspension system (PIN). Subjects were randomized, provided with one of two study prostheses, and asked to wear it for three weeks. Data was then collected during laboratory visit one, and, following one more week of wearing the first study prosthesis, during laboratory visit two. Participants were then provided with the second study intervention and asked to wear it for three weeks. Data was then collected during laboratory visit three, and, following one more week of wearing the second study intervention, during laboratory visit four. Data was not collected on the order in which participants received each study intervention
Period Title: Overall Study
STARTED	17
COMPLETED	5
NOT COMPLETED	12

Baseline Characteristics

Arm/Group Title	Entire Study Population
Arm/Group Description	Includes participants randomized to receive PIN first and VASS first.
Overall Participants	5
Age (Count of Participants)
<=18 years	0 0%
Between 18 and 65 years	5 100%
>=65 years	0 0%
Age (years) [Mean (Standard Deviation) ]
Mean (Standard Deviation) [years]	56 (9)
Sex: Female, Male (Count of Participants)
Female	0 0%
Male	5 100%
Amputation etiology (Number) [Number]
Diabetic	1 20%
Traumatic	4 80%
Years post-amputation (Years) [Mean (Standard Deviation) ]
Mean (Standard Deviation) [Years]	13 (15)
Weight (kg) [Mean (Standard Deviation) ]
Mean (Standard Deviation) [kg]	84 (11)
Height (m) [Mean (Standard Deviation) ]
Mean (Standard Deviation) [m]	1.78 (0.11)

Outcome Measures

1. Primary Outcome

Title	Limb Volume
Time Frame	Measurements were taken after wearing the study prostheses for three weeks

Outcome Measure Data

Analysis Population Description

The number of participants for analysis is equal to the number of participants who completed the study protocol.

Arm/Group Title	PIN Suspension	VASS Suspension
Arm/Group Description	A modified patellar tendon bearing socket with a pin lock suspension system (PIN)	A total surface bearing socket with a vacuum-assisted suspension system (VASS).
Measure Participants	5	5
Mean (Standard Deviation) [liters]	0.68 (.14)	0.72 (.13)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	PIN Suspension, VASS Suspension
	Comments
	Type of Statistical Test	Superiority or Other
	Comments
Statistical Test of Hypothesis	p-Value	>0.05
	Comments	Statistical significance was set a-priori at p < 0.05.
	Method	Mixed Models Analysis
	Comments	The effect of study limb on limb volume was analyzed using repeated measures one-way analyses of variance.

2. Primary Outcome

Title	Activity Level
Description	Total number of steps during a two week period ending in the fourth week for each study prosthesis (PIN and VASS).
Time Frame	Two weeks

Outcome Measure Data

Analysis Population Description

The number of participants for analysis is equal to the number of participants who completed the study protocol.

Arm/Group Title	PIN Suspension	VASS Suspension
Arm/Group Description	A modified patellar tendon bearing socket with a pin lock suspension system (PIN)	A total surface bearing socket with a vacuum-assisted suspension system (VASS).
Measure Participants	5	5
Mean (Standard Deviation) [steps (in thousands)]	73 (18)	38 (9)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	PIN Suspension, VASS Suspension
	Comments
	Type of Statistical Test	Superiority or Other
	Comments
Statistical Test of Hypothesis	p-Value	=0.0056
	Comments	Statistical significance was set a-priori at p < 0.05.
	Method	Mixed Models Analysis
	Comments	The effect of study limb on activity level was analyzed using repeated measures one-way analyses of variance.

3. Primary Outcome

Title	Limb Pistoning
Description	Limb pistoning is the change in the resultant distance between the prosthetic-side knee joint marker triad and the residual limb thigh triad measured using a 12-camera motion analysis system while subjects weighted and un-weighted their prosthesis standing in place.
Time Frame	Measurements were taken after wearing the study prosthesis for three weeks

Outcome Measure Data

Analysis Population Description

The number of participants for analysis is equal to the number of participants who completed the study protocol.

Arm/Group Title	PIN Suspension	VASS Suspension
Arm/Group Description	A modified patellar tendon bearing socket with a pin lock suspension system (PIN)	A total surface bearing socket with a vacuum-assisted suspension system (VASS).
Measure Participants	5	5
Mean (Standard Deviation) [mm]	6 (4)	1 (3)

Statistical Analysis 1

Statistical Analysis Overview	Comparison Group Selection	PIN Suspension, VASS Suspension
	Comments
	Type of Statistical Test	Superiority or Other
	Comments
Statistical Test of Hypothesis	p-Value	=0.0021
	Comments	Statistical significance was set a-priori at p < 0.05.
	Method	Mixed Models Analysis
	Comments	The effect of study limb on limb pistoning was analyzed using repeated measures one-way analyses of variance.

4. Secondary Outcome

Title	Residual Limb Health (PEQ Scale)
Description	Qualitative differences between the study limbs were assessed using the Prosthesis Evaluation Questionnaire (PEQ). This standardized, self-report instrument is specific to persons with lower limb amputations and is used to evaluate prosthetic care with regard to prescription and prosthesis-related quality of life. The Residual Limb Health scale examines: sweat, smell, volume changes, rashes, ingrown hairs, and blisters. The scale is scored from 0 to 100 where 100 indicates the best outcome (i.e., most healthful).
Time Frame	Measurements were taken after wearing the study prosthesis for four weeks

Outcome Measure Data

Analysis Population Description

The number of participants for analysis is equal to the number of participants who completed the study protocol.

Arm/Group Title	PIN Suspension	VASS Suspension
Arm/Group Description	A modified patellar tendon bearing socket with a pin lock suspension system (PIN)	A total surface bearing socket with a vacuum-assisted suspension system (VASS).
Measure Participants	5	5
Mean (Standard Deviation) [units on a scale]	90 (5)	77 (20)

5. Secondary Outcome

Title	Ambulation (PEQ Scale)
Description	Qualitative differences between the study limbs were assessed using the Prosthesis Evaluation Questionnaire (PEQ). This standardized, self-report instrument is specific to persons with lower limb amputations and is used to evaluate prosthetic care with regard to prescription and prosthesis-related quality of life. The Ambulation scale queries the ability to walk in general, in close spaces, on stairs and ramps, in urban environments, and on slippery surfaces. The scale is scored from 0 to 100 where 100 indicates the best outcome (i.e., easiest to walk on).
Time Frame	Measurements were taken after wearing the study prosthesis for four weeks

Outcome Measure Data

Analysis Population Description

The number of participants for analysis is equal to the number of participants who completed the study protocol.

Arm/Group Title	PIN Suspension	VASS Suspension
Arm/Group Description	A modified patellar tendon bearing socket with a pin lock suspension system (PIN)	A total surface bearing socket with a vacuum-assisted suspension system (VASS).
Measure Participants	5	5
Mean (Standard Deviation) [units on a scale]	95 (6)	67 (22)

6. Secondary Outcome

Title	Frustration (PEQ Scale)
Description	Qualitative differences between the study limbs were assessed using the Prosthesis Evaluation Questionnaire (PEQ). This standardized, self-report instrument is specific to persons with lower limb amputations and is used to evaluate prosthetic care with regard to prescription and prosthesis-related quality of life. Frustration was assessed by frequency of occurrence and rating. The scale is scored from 0 to 100 where 100 indicates the best outcome (i.e., least frustrating).
Time Frame	Measurements were taken after wearing the study prosthesis for four weeks

Outcome Measure Data

Analysis Population Description

The number of participants for analysis is equal to the number of participants who completed the study protocol.

Arm/Group Title	PIN Suspension	VASS Suspension
Arm/Group Description	A modified patellar tendon bearing socket with a pin lock suspension system (PIN)	A total surface bearing socket with a vacuum-assisted suspension system (VASS).
Measure Participants	5	5
Mean (Standard Deviation) [units on a scale]	91 (11)	43 (29)

Adverse Events

Arm/Group Title	Entire Study Population
Arm/Group Description	Includes participants randomized to receive PIN first and VASS first.
All Cause Mortality
	Entire Study Population
	Affected / at Risk (%)	# Events
Total	/ (NaN)
Serious Adverse Events
	Entire Study Population
	Affected / at Risk (%)	# Events
Total	0/17 (0%)
Other (Not Including Serious) Adverse Events
	Entire Study Population
	Affected / at Risk (%)	# Events
Total	1/17 (5.9%)
Injury, poisoning and procedural complications
Prosthesis failure	1/17 (5.9%)	1

Limitations/Caveats

The small number of participants who completed the protocol precluded a statistical analysis on the secondary outcome measures.

More Information

Certain Agreements

All Principal Investigators ARE employed by the organization sponsoring the study.

There is NOT an agreement between Principal Investigators and the Sponsor (or its agents) that restricts the PI's rights to discuss or publish trial results after the trial is completed.