Trial Outcomes & Findings for Pivot-Flex Foot: Optimal Coupling Ratio Between Transverse and Sagittal-plane Motions Using a Torsionally Adaptive Prosthesis for Individuals With Lower Limb Amputation (NCT NCT03532100)
NCT ID: NCT03532100
Last Updated: 2025-11-19
Results Overview
Peak transverse-plane prosthetic socket torque measured while walking normalized to body mass
Recruitment status
COMPLETED
Study phase
NA
Target enrollment
14 participants
Primary outcome timeframe
During walking trials for each coupling ratio
Results posted on
2025-11-19
Participant Flow
Two enrolled participants decided they were no longer interested in participating before beginning the study protocol. One enrolled participant had a long residual limb and could not accommodate the build height of the study intervention.
Participant milestones
| Measure |
Individuals With a Lower Limb Prosthesis
In this cross-over study, all subjects were asked to perform 3 activities:
1. Walking in a straight line while wearing the study intervention (prosthesis),
2. Walking around a 2-meter diameter circle with the study intervention (prosthesis) on the inside of the circle, and
3. Walking around a 2-meter diameter circle with the study intervention (prosthesis) on the outside of the circle.
While performing each of these activities, the study intervention was set to 5 different settings (5 sagittal:transverse coupling ratio, 1:0, 6:1, 4:1, 3:1, and 2:1). These settings were block randomized and blinded to the participant.
The study was conducted over two visits with overnight rest in between each visit. During the first study visit, participants performed the walking in a straight line activity. During the second study visit, participants walked around a 2-meter diameter circle with the study intervention (prosthesis) on the inside and the outside of the circle. The order in which the participants walked with the study intervention (prosthesis) on the inside or the outside of the circle was randomized.
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|---|---|
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Overall Study
STARTED
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11
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Overall Study
** Straight Line Walking
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11
|
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Overall Study
Straight Line Walking With 0:1 Coupling Ratio
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11
|
|
Overall Study
Straight Line Walking With 1:6 Coupling Ratio
|
11
|
|
Overall Study
Straight Line Walking With 1:4 Coupling Ratio
|
11
|
|
Overall Study
Straight Line Walking With 1:3 Coupling Ratio
|
11
|
|
Overall Study
Straight Line Walking With 1:2 Coupling Ratio
|
11
|
|
Overall Study
** Circle Walking With Prosthesis on the Inside
|
11
|
|
Overall Study
Circle Walking With Prosthesis on the Inside and 0:1 Coupling Ratio
|
11
|
|
Overall Study
Circle Walking With Prosthesis on the Inside and 1:6 Coupling Ratio
|
11
|
|
Overall Study
Circle Walking With Prosthesis on the Inside and 1:4 Coupling Ratio
|
11
|
|
Overall Study
Circle Walking With Prosthesis on the Inside and 1:3 Coupling Ratio
|
11
|
|
Overall Study
Circle Walking With Prosthesis on the Inside and 1:2 Coupling Ratio
|
11
|
|
Overall Study
** Circle Walking With Prosthesis on the Outside
|
10
|
|
Overall Study
Circle Walking With Prosthesis on the Outside and 0:1 Coupling Ratio
|
10
|
|
Overall Study
Circle Walking With Prosthesis on the Outside and 1:6 Coupling Ratio
|
10
|
|
Overall Study
Circle Walking With Prosthesis on the Outside and 1:4 Coupling Ratio
|
10
|
|
Overall Study
Circle Walking With Prosthesis on the Outside and 1:3 Coupling Ratio
|
10
|
|
Overall Study
Circle Walking With Prosthesis on the Outside and 1:2 Coupling Ratio
|
10
|
|
Overall Study
COMPLETED
|
10
|
|
Overall Study
NOT COMPLETED
|
1
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Reasons for withdrawal
| Measure |
Individuals With a Lower Limb Prosthesis
In this cross-over study, all subjects were asked to perform 3 activities:
1. Walking in a straight line while wearing the study intervention (prosthesis),
2. Walking around a 2-meter diameter circle with the study intervention (prosthesis) on the inside of the circle, and
3. Walking around a 2-meter diameter circle with the study intervention (prosthesis) on the outside of the circle.
While performing each of these activities, the study intervention was set to 5 different settings (5 sagittal:transverse coupling ratio, 1:0, 6:1, 4:1, 3:1, and 2:1). These settings were block randomized and blinded to the participant.
The study was conducted over two visits with overnight rest in between each visit. During the first study visit, participants performed the walking in a straight line activity. During the second study visit, participants walked around a 2-meter diameter circle with the study intervention (prosthesis) on the inside and the outside of the circle. The order in which the participants walked with the study intervention (prosthesis) on the inside or the outside of the circle was randomized.
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|---|---|
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Overall Study
Intervention malfunction
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1
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Baseline Characteristics
Pivot-Flex Foot: Optimal Coupling Ratio Between Transverse and Sagittal-plane Motions Using a Torsionally Adaptive Prosthesis for Individuals With Lower Limb Amputation
Baseline characteristics by cohort
| Measure |
Individuals With a Lower Limb Amputation
n=11 Participants
All participants were block randomized to the order in which they walked in a straight line, walked around a 2m diameter circle with their prosthesis on the inside of the circle, and walked around a 2m diameter circle with their prosthesis on the outside of the circle. Additionally, the order of the sagittal:transverse coupling ratio of 1:0, 6:1, 4:1, 3:1, and 2:1 were also block randomized and blinded to the participant.
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|---|---|
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Age, Continuous
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53 years
STANDARD_DEVIATION 15
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Sex: Female, Male
Female
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0 Participants
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Sex: Female, Male
Male
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11 Participants
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Ethnicity (NIH/OMB)
Hispanic or Latino
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0 Participants
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Ethnicity (NIH/OMB)
Not Hispanic or Latino
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11 Participants
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Ethnicity (NIH/OMB)
Unknown or Not Reported
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0 Participants
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Race (NIH/OMB)
American Indian or Alaska Native
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0 Participants
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Race (NIH/OMB)
Asian
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0 Participants
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Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
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0 Participants
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Race (NIH/OMB)
Black or African American
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0 Participants
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Race (NIH/OMB)
White
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10 Participants
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|
Race (NIH/OMB)
More than one race
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1 Participants
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Race (NIH/OMB)
Unknown or Not Reported
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0 Participants
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PRIMARY outcome
Timeframe: During walking trials for each coupling ratioPeak transverse-plane prosthetic socket torque measured while walking normalized to body mass
Outcome measures
| Measure |
Straight Line Walking
n=11 Participants
All participants will walk in a straight line while wearing the study prosthesis. The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes.
Torsionally adaptive prosthesis with 0:1 coupling ratio. A coupling ratio (transverse:sagittal) of 0:1 means there will be no coupling between the transverse- and sagittal-plane motion. That is, regardless of any motion in the sagittal plane, there will be zero motion in the transverse plane.
Torsionally adaptive prosthesis with 1:6 coupling ratio. A coupling ratio (transverse:sagittal) of 1:6 means there will be one degree of motion in the transverse plane for every six degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:4 coupling ratio. A coupling ratio (transverse:sagittal) of 1:4 means there will be one degree of motion in the transverse plane for every four degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:3 coupling ratio. A coupling ratio (transverse:sagittal) of 1:3 means there will be one degree of motion in the transverse plane for every three degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:2 coupling ratio. A coupling ratio (transverse:sagittal) of 1:2 means there will be one degree of motion in the transverse plane for every two degrees of motion in the sagittal plane.
|
Circle Walking With Prosthesis Inside
n=11 Participants
All participants will walk around a 1-meter radius circle with their prosthesis on the inside of the circle. The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes.
Torsionally adaptive prosthesis with 0:1 coupling ratio. A coupling ratio (transverse:sagittal) of 0:1 means there will be no coupling between the transverse- and sagittal-plane motion. That is, regardless of any motion in the sagittal plane, there will be zero motion in the transverse plane.
Torsionally adaptive prosthesis with 1:6 coupling ratio. A coupling ratio (transverse:sagittal) of 1:6 means there will be one degree of motion in the transverse plane for every six degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:4 coupling ratio. A coupling ratio (transverse:sagittal) of 1:4 means there will be one degree of motion in the transverse plane for every four degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:3 coupling ratio. A coupling ratio (transverse:sagittal) of 1:3 means there will be one degree of motion in the transverse plane for every three degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:2 coupling ratio. A coupling ratio (transverse:sagittal) of 1:2 means there will be one degree of motion in the transverse plane for every two degrees of motion in the sagittal plane.
|
Circle Walking With Prosthesis Outside
n=10 Participants
All participants will walk around a 1-meter radius circle with their prosthesis on the outside of the circle. The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes.
Torsionally adaptive prosthesis with 0:1 coupling ratio. A coupling ratio (transverse:sagittal) of 0:1 means there will be no coupling between the transverse- and sagittal-plane motion. That is, regardless of any motion in the sagittal plane, there will be zero motion in the transverse plane.
Torsionally adaptive prosthesis with 1:6 coupling ratio. A coupling ratio (transverse:sagittal) of 1:6 means there will be one degree of motion in the transverse plane for every six degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:4 coupling ratio. A coupling ratio (transverse:sagittal) of 1:4 means there will be one degree of motion in the transverse plane for every four degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:3 coupling ratio. A coupling ratio (transverse:sagittal) of 1:3 means there will be one degree of motion in the transverse plane for every three degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:2 coupling ratio. A coupling ratio (transverse:sagittal) of 1:2 means there will be one degree of motion in the transverse plane for every two degrees of motion in the sagittal plane.
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Peak Transverse-plane Prosthetic Socket Torque Normalized to Body Mass
Sagittal:transverse coupling ratio 2:1
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0.350 Nm/kg
Standard Error 0.019
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0.349 Nm/kg
Standard Error 0.021
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0.358 Nm/kg
Standard Error 0.021
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Peak Transverse-plane Prosthetic Socket Torque Normalized to Body Mass
Sagittal:transverse coupling ratio 1:0
|
0.299 Nm/kg
Standard Error 0.025
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0.340 Nm/kg
Standard Error 0.026
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0.306 Nm/kg
Standard Error 0.026
|
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Peak Transverse-plane Prosthetic Socket Torque Normalized to Body Mass
Sagittal:transverse coupling ratio 6:1
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0.292 Nm/kg
Standard Error 0.013
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0.324 Nm/kg
Standard Error 0.023
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0.306 Nm/kg
Standard Error 0.026
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Peak Transverse-plane Prosthetic Socket Torque Normalized to Body Mass
Sagittal:transverse coupling ratio 4:1
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0.312 Nm/kg
Standard Error 0.011
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0.331 Nm/kg
Standard Error 0.023
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0.322 Nm/kg
Standard Error 0.025
|
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Peak Transverse-plane Prosthetic Socket Torque Normalized to Body Mass
Sagittal:transverse coupling ratio 3:1
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0.323 Nm/kg
Standard Error 0.012
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0.343 Nm/kg
Standard Error 0.019
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0.336 Nm/kg
Standard Error 0.021
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SECONDARY outcome
Timeframe: Immediately following walking trials for each coupling ratioAn 11-point Likert scale will be used to record the subject's perception of satisfaction with the prosthesis after completing the trials for each coupling ratio. Participants will be asked to rate their satisfaction with the prosthesis on a 0 - 10 scale. Zero represented the most uncomfortable socket fit the subject could imagine, and ten represented the most comfortable socket fit.
Outcome measures
| Measure |
Straight Line Walking
n=11 Participants
All participants will walk in a straight line while wearing the study prosthesis. The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes.
Torsionally adaptive prosthesis with 0:1 coupling ratio. A coupling ratio (transverse:sagittal) of 0:1 means there will be no coupling between the transverse- and sagittal-plane motion. That is, regardless of any motion in the sagittal plane, there will be zero motion in the transverse plane.
Torsionally adaptive prosthesis with 1:6 coupling ratio. A coupling ratio (transverse:sagittal) of 1:6 means there will be one degree of motion in the transverse plane for every six degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:4 coupling ratio. A coupling ratio (transverse:sagittal) of 1:4 means there will be one degree of motion in the transverse plane for every four degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:3 coupling ratio. A coupling ratio (transverse:sagittal) of 1:3 means there will be one degree of motion in the transverse plane for every three degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:2 coupling ratio. A coupling ratio (transverse:sagittal) of 1:2 means there will be one degree of motion in the transverse plane for every two degrees of motion in the sagittal plane.
|
Circle Walking With Prosthesis Inside
n=11 Participants
All participants will walk around a 1-meter radius circle with their prosthesis on the inside of the circle. The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes.
Torsionally adaptive prosthesis with 0:1 coupling ratio. A coupling ratio (transverse:sagittal) of 0:1 means there will be no coupling between the transverse- and sagittal-plane motion. That is, regardless of any motion in the sagittal plane, there will be zero motion in the transverse plane.
Torsionally adaptive prosthesis with 1:6 coupling ratio. A coupling ratio (transverse:sagittal) of 1:6 means there will be one degree of motion in the transverse plane for every six degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:4 coupling ratio. A coupling ratio (transverse:sagittal) of 1:4 means there will be one degree of motion in the transverse plane for every four degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:3 coupling ratio. A coupling ratio (transverse:sagittal) of 1:3 means there will be one degree of motion in the transverse plane for every three degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:2 coupling ratio. A coupling ratio (transverse:sagittal) of 1:2 means there will be one degree of motion in the transverse plane for every two degrees of motion in the sagittal plane.
|
Circle Walking With Prosthesis Outside
n=10 Participants
All participants will walk around a 1-meter radius circle with their prosthesis on the outside of the circle. The torsionally adaptive prosthesis can be programmed to couple the motion between the transverse- and sagittal-planes.
Torsionally adaptive prosthesis with 0:1 coupling ratio. A coupling ratio (transverse:sagittal) of 0:1 means there will be no coupling between the transverse- and sagittal-plane motion. That is, regardless of any motion in the sagittal plane, there will be zero motion in the transverse plane.
Torsionally adaptive prosthesis with 1:6 coupling ratio. A coupling ratio (transverse:sagittal) of 1:6 means there will be one degree of motion in the transverse plane for every six degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:4 coupling ratio. A coupling ratio (transverse:sagittal) of 1:4 means there will be one degree of motion in the transverse plane for every four degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:3 coupling ratio. A coupling ratio (transverse:sagittal) of 1:3 means there will be one degree of motion in the transverse plane for every three degrees of motion in the sagittal plane.
Torsionally adaptive prosthesis with 1:2 coupling ratio. A coupling ratio (transverse:sagittal) of 1:2 means there will be one degree of motion in the transverse plane for every two degrees of motion in the sagittal plane.
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Satisfaction With the Prosthesis
Sagittal:transverse coupling ratio 1:0
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8.0 score on a scale
Standard Deviation 1.3
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7.5 score on a scale
Standard Deviation 1.3
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7.7 score on a scale
Standard Deviation 1.7
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Satisfaction With the Prosthesis
Sagittal:transverse coupling ratio 6:1
|
8.2 score on a scale
Standard Deviation 1.3
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7.9 score on a scale
Standard Deviation 1.1
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7.9 score on a scale
Standard Deviation 1.2
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Satisfaction With the Prosthesis
Sagittal:transverse coupling ratio 4:1
|
8.0 score on a scale
Standard Deviation 1.0
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7.1 score on a scale
Standard Deviation 1.7
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7.4 score on a scale
Standard Deviation 1.3
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Satisfaction With the Prosthesis
Sagittal:transverse coupling ratio 3:1
|
7.7 score on a scale
Standard Deviation 1.2
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7.5 score on a scale
Standard Deviation 0.7
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7.8 score on a scale
Standard Deviation 1.1
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Satisfaction With the Prosthesis
Sagittal:transverse coupling ratio 2:1
|
8.5 score on a scale
Standard Deviation 1.0
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8.1 score on a scale
Standard Deviation 1.3
|
7.7 score on a scale
Standard Deviation 1.5
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Adverse Events
Individuals With a Lower Limb Amputation
Serious events: 0 serious events
Other events: 0 other events
Deaths: 0 deaths
Serious adverse events
Adverse event data not reported
Other adverse events
Adverse event data not reported
Additional Information
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place