Assessing the DSR Ankle

Assessment of a Microprocessor Ankle for Low Mobility Individuals

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT05955378

Enrollment

Registered

2023-07-21

Start date

2023-08-22

Completion date

2024-12-19

Last updated

2025-07-01

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Amputation, Limb Deficiencies

Keywords

Amputation, Transtibial, K2, Limited Community Ambulator

Brief summary

This research is being done to conduct a preliminary investigation into a new prosthetic microprocessor controlled (MPC) ankle, called the Damping, Stiffness, and Repositioning (DSR) ankle. The DSR ankle is a new design to support a person while they walk on both even and uneven ground, as well as with bending the ankle for safe foot clearance while a person takes a step. In particular, in this study we are interested in seeing how this type of new device may benefit people who are rated as a K2-level ambulator.

Detailed description

Synchro Motion, LLC developed a novel MPC ankle. Because of its unique actuation scheme, the prosthesis can behave as: (1) a lockable conformal damper, (2) a variable set-point spring, and (3) an actively repositionable joint. The investigators therefore refer to the device as the damping, stiffness, and repositioning (DSR) ankle. The DSR ankle is small, lightweight, quiet, and runs for multiple days on a single charge. No other commercially available prosthesis combines this set of features. It will be shown in preliminary work that the features of the DSR ankle can increase toe clearance in swing, reduce the time-to-foot-flat after heel strike, and improve weight bearing symmetry when standing on slopes for K3 Individuals with Lower Limb Amputation (ILLAs). These biomechanical functions have all been linked to improved safety and stability, which leads the investigators to hypothesize that the DSR ankle may provide benefits to K2 ILLAs as well. The main purpose of this research is to determine the ways in which the DSR ankle may be adapted to provide benefits specifically to ILLAs who use their prosthesis at the K2 level. For purposes of the Phase I work, the development and assessment will be performed exclusively with K2 ILLAs in order to provide an opportunity to implement any necessary refinements to the DSR ankle to ensure optimal K2 performance. The remainder of the research is to quantify the effectiveness of the DSR ankle as compared to a predicate non-MPC ankle in improving performance for K2 ILLAs.

Interventions

DEVICEDSR Ankle

This is the experimental ankle component used in the overall prosthetic intervention.

DEVICEPredicate Ankle

This is the participant's prescribed ankle/foot complex used in the overall prosthetic intervention.

Study design

Allocation

RANDOMIZED

Intervention model

CROSSOVER

Primary purpose

BASIC_SCIENCE

Masking

NONE

Intervention model description

AB/BA

Eligibility

Sex/Gender

ALL

Age

18 Years to 89 Years

Healthy volunteers

Inclusion criteria

1. Adults aged 18-89 years 2. Patients who have a unilateral transtibial amputation who are able to use a prosthesis and who currently use a passive, non-MPC prosthesis 3. K2 level ambulators

Exclusion criteria

1. Pregnant women 2. Children (\<18 years old) 3. Prisoners or institutionalized individuals 4. Individuals who have the inability to give informed consent 5. Participants unable to walk for 2 minutes without an assistive device 6. Participants with complicating health conditions that interfere with the study 7. Inability to read and understand the English language. As this is a pilot study with a small sample size, it is prohibitive to translate Study documents to other languages as recruitment will be from a sample of convenience.

Design outcomes

Primary

Measure	Time frame	Description
Minimum Foot Clearance	after up to 3 weeks of training	Minimum foot clearance is the shortest distance between the foot and the ground during swing, and it occurs approximately halfway through the swing phase of gait.
Time to Foot Flat	after up to 3 weeks of training	Time to foot flat is the duration of time between initial contact at heel strike and the full contact of the sole of the foot on the ground in stance.

Secondary

Measure	Time frame	Description
Orthotics Prosthetics User Survey (OPUS) Device Satisfaction	after up to 3 weeks of training	The OPUS is a self-report questionnaire consisting of 5 modules. It can be used for prosthetic and orthotic programs for quality assessment, to maintain awareness of improvement in activities, to evaluate changes in patient's functional status and quality of life, and to assess satisfaction with devices and services. The Device Satisfaction module uses a 5-point Likert scale (1 to 5), with a total score range of 11 to 55. Higher values indicate higher levels of satisfaction.
10 Meter Walk Test (10 MWT)	after up to 3 weeks of training	The 10 MWT assesses walking speed in meters per second over a distance of 10 meters.
Six Minute Walk Test (6 MWT)	after up to 3 weeks of training	The 6 MWT assesses walking distance in meters over a period of 6 minutes.
Timed Up and Go (TUG)	after up to 3 weeks of training	The TUG assesses mobility, balance, walking ability, and fall risk in older adults.

Countries

United States

Participant flow

Recruitment details

5 patients were enrolled between August 22, 2023 and November 19, 2024 at the Shirley Ryan AbilityLab in Chicago, IL.

Pre-assignment details

3 of 5 patients completed this cross-over study.

Participants by arm

Arm	Count
Predicate Ankle, Then DSR Ankle Participants first performed assessments with their predicate (daily use) prosthetic ankle. After a washout period of at least 2 weeks, they were trained and assessed with the DSR Ankle. The DSR Ankle is a novel microprocessor-controlled ankle prosthesis that is able to provide enhanced mobility and stability to individuals with lower limb amputation.	2
DSR Ankle, Then Predicate Ankle Participants first performed assessments with the DSR Ankle. The DSR Ankle is a novel microprocessor-controlled ankle prosthesis that is able to provide enhanced mobility and stability to individuals with lower limb amputation. After a washout period of at least 2 weeks, they were trained and assessed with their predicate (daily use) prosthetic ankle.	1
Total	3

Baseline characteristics

Characteristic	DSR Ankle, Then Predicate Ankle	Total	Predicate Ankle, Then DSR Ankle
Age, Categorical <=18 years	0 Participants	0 Participants	0 Participants
Age, Categorical >=65 years	0 Participants	2 Participants	2 Participants
Age, Categorical Between 18 and 65 years	1 Participants	1 Participants	0 Participants
Age, Continuous	59 years STANDARD_DEVIATION 0	74.3 years STANDARD_DEVIATION 13.4	82 years STANDARD_DEVIATION 2.8
Race and Ethnicity Not Collected	—	0 Participants	—
Region of Enrollment United States	1 participants	3 participants	2 participants
Sex: Female, Male Female	1 Participants	2 Participants	1 Participants
Sex: Female, Male Male	0 Participants	1 Participants	1 Participants

Adverse events

Event type	EG000 affected / at risk	EG001 affected / at risk
deaths Total, all-cause mortality	0 / 5	0 / 5
other Total, other adverse events	0 / 5	0 / 5
serious Total, serious adverse events	0 / 5	0 / 5

Outcome results

Primary

Minimum Foot Clearance

Minimum foot clearance is the shortest distance between the foot and the ground during swing, and it occurs approximately halfway through the swing phase of gait.