Lower Limb Amputation Below Knee (Injury)
Conditions
Keywords
Prosthetic Socket, Amputee, Adjustable Socket
Brief summary
The aim of this research is to create a prosthetic system that will automatically adjust the fit of the socket and create a well-fitting prosthesis for people with leg amputations who experience volume fluctuations when using their prosthesis.
Detailed description
People with lower limb amputations often experience daily changes in the size (volume) of their residual limb. These daily changes can cause a prosthesis to fit poorly. They can also cause limb health problems including skin breakdown and injury to deeper tissues. Prosthetic socket systems that accommodate limb volume changes can help address these issues, but they require users to make adjustments throughout the day. The objective of this research is to develop and test an automatically-adjusting prosthetic socket system for prosthesis users. The system integrates with a range of adjustable socket technologies, including those that are commercially available. The system allows small size adjustments for both tightening and loosening the socket. In early aims of the study, the prosthesis will be adjusted manually, but can be controlled remotely, eliminating the need to remove the prosthesis or bend down to make adjustments. The system will later be enhanced to automatically change the fit of an adjustable socket at the appropriate times, without distracting the user. We hypothesize that this system will help to maintain consistent limb fluid volume while the prosthesis user is wearing the socket and that socket fit will be improved. The system functions by continuously collecting measurements from sensors within the socket and uses small motors to control adjustable panels in the socket wall.
Interventions
DEVICEAdjustable socket
The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume.
Sponsors
University of Washington
Study design
Allocation
NON_RANDOMIZED
Intervention model
SINGLE_GROUP
Primary purpose
SUPPORTIVE_CARE
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* 18 years of age or older * Unilateral transtibial amputee * At least 6 months post-amputation * Wear prosthesis at least 3 hours per day * Use an elastomeric (i.e. gel) liner * K3 or higher Medicare Functional Classification Level * Able to walk continuously with prosthesis for at least 5 minutes at a time, sit, stand, and step up a height of 5.0 cm. * Residual limb of 9.0 cm or longer * Experience problems with volume fluctuations that affect their prosthetic socket fit
Exclusion criteria
* Participants experiencing skin breakdown on enrollment will be excluded, but can enter after having been free of clinically visually-apparent skin breakdown for two weeks.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in Limb Volume | Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes. | Limb volume fluctuations will be measured in real-time as socket adjustment strategies are tested. This will be accomplished using a portable bioimpedance device with thin sticky electrodes that are placed on the residual limb. Specifically, the change in limb volume will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made. |
| Change in Limb Movement | Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes. | Limb movement within the socket will be measured as socket adjustment strategies are tested. It will be used as an indicator of how well the socket is fitting (loose, tight, etc). The measurement will be made using an inductance sensor that is placed in the socket which measures the displacement of a sensor patch on the prosthetic liner. Specifically, the change in limb movement will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made. |
| Number of Participants With Increase in Limb Fluid Volume After Panel Pull | Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes. | Limb volume fluctuations will be measured in real-time as socket adjustment strategies are tested. This will be accomplished using a portable bioimpedance device with thin sticky electrodes that are placed on the residual limb. Specifically, the change in limb volume will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made. |
| Integral of Absolute Error to Maintain Set Point | Over 30 minutes of controlled use of the auto-adjusting socket | Clinically acceptable socket volume error as measured by an automatically adjusting prosthetic socket attempting to maintain a set socket volume set point, based on sensed distance (measured in mm). |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Adjustable Socket Mode Preference | After 3 weeks of use, where each mode was tested for about 1 week | Participants tested the adjustable prosthesis in their home environment in one of three adjustment configurations: 1. locked where panels were kept in position and did not move, similar to their own prosthesis 2. manual where panels were able to be adjusted inward or outward radially, by the participant via a phone app 3. automatic where panels adjusted inward or outward radially as when the participant walked for a sufficiently continuous amount of time. Participants were also able to manual adjust panels as needed in this mode as well. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls An adjustable socket is tested where researchers control the adjustments. This arm focuses on socket size adjustments while walking.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 15 |
| Aim 3 - Adjustable Socket - Participant Controls An adjustable socket is tested where the study participant controls the adjustments. This arm focuses on socket size adjustments while walking.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 13 |
| Aim 4 - Adjustable Socket - Automatic Controls An adjustable socket is tested where a control system is used to automatically control the adjustments. This arm focuses on socket size adjustments while walking.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 12 |
| Aim 6A - Release/Recovery - Researcher Controls An adjustable socket is tested where researchers control the adjustments. This arm focuses on a socket release and recovery mechanism that allows for full or partial doffing of the socket while seated.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 13 |
| Aim 6B - Release/Recovery - Participant Controls An adjustable socket is tested where the study participant controls the adjustments. This arm focuses on a socket release and recovery mechanism that allows for full or partial doffing of the socket while seated.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 7 |
| Aim 8 - Panel Pull During Resting The purpose of Aim #8 was to determine if vacuum-like action (panel pull) during resting between periods of activity facilitated limb fluid volume recovery and retention in transtibial prosthesis users. Liner attached to panels.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 14 |
| Aim 9 - Panel Pull During Ambulation Extending from the Aim #8 results, we sought to determine in Aim #9 if vacuum-like action during ambulation facilitated limb fluid volume recovery and retention. Vacuum-like action was achieved by quickly pulling the panels and liner (liner attached to panels) radially outward during late stance phase and then moving them back to their original position during early swing.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 12 |
| Aim 10 - Adjustable Socket Out of Lab Testing Participants took the investigational device home in one of three test modes. In the first mode, the panels were in a locked flush position, similar to their traditional prosthesis. Participants were not able to adjust the panels in this first mode. The second mode allowed participants to manually make panel adjustments, incrementally enlarging or tightening the panels radially. Lastly, the third mode implemented the automated controller developed in the previous aims. Participants were still able to make manual adjustments to the panel positions but during walks adjustments would also occur automatically. Each mode was tested for a minimum of 1 week.
Adjustable socket: The adjustable prosthetic socket will be used to test the influence of socket size adjustments during sitting, standing, and walking activities to determine if these strategies can be used to improve socket fit and reduce fluctuations in limb volume. | 18 |
| Total | 104 |
Baseline characteristics
| Characteristic | Total | Aim 3 - Adjustable Socket - Participant Controls | Aim 4 - Adjustable Socket - Automatic Controls | Aim 6A - Release/Recovery - Researcher Controls | Aim 2 - Adjustable Socket - Researcher Controls | Aim 6B - Release/Recovery - Participant Controls | Aim 8 - Panel Pull During Resting | Aim 9 - Panel Pull During Ambulation | Aim 10 - Adjustable Socket Out of Lab Testing |
|---|---|---|---|---|---|---|---|---|---|
| Age, Categorical <=18 years | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Age, Categorical >=65 years | 17 Participants | 2 Participants | 2 Participants | 2 Participants | 2 Participants | 1 Participants | 2 Participants | 2 Participants | 4 Participants |
| Age, Categorical Between 18 and 65 years | 87 Participants | 11 Participants | 10 Participants | 11 Participants | 13 Participants | 6 Participants | 12 Participants | 10 Participants | 14 Participants |
| Ethnicity (NIH/OMB) Hispanic or Latino | 10 Participants | 1 Participants | 1 Participants | 1 Participants | 2 Participants | 1 Participants | 1 Participants | 1 Participants | 2 Participants |
| Ethnicity (NIH/OMB) Not Hispanic or Latino | 94 Participants | 12 Participants | 11 Participants | 12 Participants | 13 Participants | 6 Participants | 13 Participants | 11 Participants | 16 Participants |
| Ethnicity (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Asian | 1 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 1 Participants |
| Race (NIH/OMB) Black or African American | 13 Participants | 2 Participants | 2 Participants | 2 Participants | 2 Participants | 1 Participants | 1 Participants | 1 Participants | 2 Participants |
| Race (NIH/OMB) More than one race | 6 Participants | 0 Participants | 0 Participants | 0 Participants | 3 Participants | 0 Participants | 1 Participants | 1 Participants | 1 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants | 0 Participants |
| Race (NIH/OMB) White | 84 Participants | 11 Participants | 10 Participants | 11 Participants | 10 Participants | 6 Participants | 12 Participants | 10 Participants | 14 Participants |
| Region of Enrollment United States | 104 participants | 13 participants | 12 participants | 13 participants | 15 participants | 7 participants | 14 participants | 12 participants | 18 participants |
| Sex: Female, Male Female | 13 Participants | 2 Participants | 2 Participants | 2 Participants | 2 Participants | 1 Participants | 1 Participants | 1 Participants | 2 Participants |
| Sex: Female, Male Male | 91 Participants | 11 Participants | 10 Participants | 11 Participants | 13 Participants | 6 Participants | 13 Participants | 11 Participants | 16 Participants |
Adverse events
| Event type | EG000 affected / at risk | EG001 affected / at risk | EG002 affected / at risk | EG003 affected / at risk | EG004 affected / at risk | EG005 affected / at risk | EG006 affected / at risk | EG007 affected / at risk | EG008 affected / at risk |
|---|---|---|---|---|---|---|---|---|---|
| deaths Total, all-cause mortality | 0 / 15 | 0 / 13 | 0 / 12 | 0 / 9 | 0 / 13 | 0 / 7 | 0 / 14 | 0 / 12 | 0 / 18 |
| other Total, other adverse events | 0 / 15 | 0 / 13 | 0 / 12 | 0 / 9 | 0 / 13 | 0 / 7 | 0 / 14 | 0 / 12 | 0 / 18 |
| serious Total, serious adverse events | 0 / 15 | 0 / 13 | 0 / 12 | 0 / 9 | 0 / 13 | 0 / 7 | 0 / 14 | 0 / 12 | 0 / 18 |
Outcome results
Primary
Change in Limb Movement
Limb movement within the socket will be measured as socket adjustment strategies are tested. It will be used as an indicator of how well the socket is fitting (loose, tight, etc). The measurement will be made using an inductance sensor that is placed in the socket which measures the displacement of a sensor patch on the prosthetic liner. Specifically, the change in limb movement will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made.
Time frame: Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes.
Population: Change in Limb Movement was only measured for Arm 3.
| Arm | Measure | Group | Value (MEDIAN) |
|---|---|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Movement | Sensed Distance, Total Change in Response to Enlargement of Socket Size | 0.01 Millimeters |
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Movement | Sensed Distance, Total Change in Response to Reduction of Socket Size | -0.03 Millimeters |
Primary
Change in Limb Volume
Limb volume fluctuations will be measured in real-time as socket adjustment strategies are tested. This will be accomplished using a portable bioimpedance device with thin sticky electrodes that are placed on the residual limb. Specifically, the change in limb volume will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made.
Time frame: Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes.
Population: Change in Limb Volume was monitored only for Arms 2, 6A, 6B, 8 and 9.~Participants were grouped according to their responses to the intervention. The groups immediate limb volume increase and decrease in rate of limb volume loss presented below are not mutually exclusive. Some participants that experienced immediate limb volume increase were also seen to exhibit a decrease in the rate of limb volume loss.
| Arm | Measure | Group | Value (NUMBER) |
|---|---|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Volume | Immediate Limb Volume Increase | 9 participants |
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Volume | Decrease in rate of limb volume loss | 7 participants |
Primary
Change in Limb Volume
Limb volume fluctuations will be measured in real-time as socket adjustment strategies are tested. This will be accomplished using a portable bioimpedance device with thin sticky electrodes that are placed on the residual limb. Specifically, the change in limb volume will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made.
Time frame: Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes.
Population: Change in Limb Volume was monitored only for Arms 2, 6A, 6B, 8 and 9.
| Arm | Measure | Category | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Volume | Experienced limb volume change | 8 Participants |
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Volume | Maintained limb volume | 2 Participants |
Primary
Change in Limb Volume
Limb volume fluctuations will be measured in real-time as socket adjustment strategies are tested. This will be accomplished using a portable bioimpedance device with thin sticky electrodes that are placed on the residual limb. Specifically, the change in limb volume will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made.
Time frame: Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes.
Population: Change in Limb Volume was monitored only for Arms 2, 6A, 6B, 8 and 9.
| Arm | Measure | Group | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Volume | Loss of Limb Fluid Volume | 3 Participants |
| Aim 2 - Adjustable Socket - Researcher Controls | Change in Limb Volume | Gain in Limb Fluid Volume | 3 Participants |
| Aim 8 - Panel Pull During Resting | Change in Limb Volume | Gain in Limb Fluid Volume | 12 Participants |
| Aim 8 - Panel Pull During Resting | Change in Limb Volume | Loss of Limb Fluid Volume | 0 Participants |
Primary
Integral of Absolute Error to Maintain Set Point
Clinically acceptable socket volume error as measured by an automatically adjusting prosthetic socket attempting to maintain a set socket volume set point, based on sensed distance (measured in mm).
Time frame: Over 30 minutes of controlled use of the auto-adjusting socket
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls | Integral of Absolute Error to Maintain Set Point | 0.003 Millimeters |
Primary
Number of Participants With Increase in Limb Fluid Volume After Panel Pull
Limb volume fluctuations will be measured in real-time as socket adjustment strategies are tested. This will be accomplished using a portable bioimpedance device with thin sticky electrodes that are placed on the residual limb. Specifically, the change in limb volume will be assessed from a baseline period where no socket adjustments are made to another period within the same test session where socket adjustments are made.
Time frame: Change from baseline period (non-adjustment) to test period (adjustment), commonly each 1 hour long and separated by a seated period of approximately 30 minutes.
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls | Number of Participants With Increase in Limb Fluid Volume After Panel Pull | 8 Participants |
Secondary
Adjustable Socket Mode Preference
Participants tested the adjustable prosthesis in their home environment in one of three adjustment configurations: 1. locked where panels were kept in position and did not move, similar to their own prosthesis 2. manual where panels were able to be adjusted inward or outward radially, by the participant via a phone app 3. automatic where panels adjusted inward or outward radially as when the participant walked for a sufficiently continuous amount of time. Participants were also able to manual adjust panels as needed in this mode as well.
Time frame: After 3 weeks of use, where each mode was tested for about 1 week
| Arm | Measure | Category | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|---|
| Aim 2 - Adjustable Socket - Researcher Controls | Adjustable Socket Mode Preference | Preferred Automatic Mode | 5 Participants |
| Aim 2 - Adjustable Socket - Researcher Controls | Adjustable Socket Mode Preference | Preferred Manual Mode | 5 Participants |
| Aim 2 - Adjustable Socket - Researcher Controls | Adjustable Socket Mode Preference | Preferred Locked Mode | 0 Participants |