Assessing the DSR Ankle

Assessment of a Microprocessor Ankle for Low Mobility Individuals

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.

Study Overview

• Status: Completed
• Conditions: Amputation; Limb Deficiencies
• Intervention / Treatment: Device: DSR Ankle; Device: Predicate Ankle

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.

• Study Type: Interventional
• Enrollment (Actual): 5
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Illinois
    • Chicago, Illinois, United States, 60611-4805
      • Shirley Ryan Abilitylab

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: 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. It interfaces to the user by attaching to their socket via an industry-standard pyramid connector.	Device: DSR Ankle; This is the experimental ankle component used in the overall prosthetic intervention.; Other Names: The Damping, Stiffness and Repositioning Ankle
Active Comparator: Predicate Ankle; The predicate ankle is the user's prescribed prosthesis worn for the activities of daily living.	Device: Predicate Ankle; This is the participant's prescribed ankle/foot complex used in the overall prosthetic intervention.; Other Names: Daily Use Ankle

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	after up to 3 weeks of training
Time to Foot Flat	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.	after up to 3 weeks of training

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
10 Meter Walk Test (10 MWT)	The 10 MWT assesses walking speed in meters per second over a distance of 10 meters.	after up to 3 weeks of training
Six Minute Walk Test (6 MWT)	The 6 MWT assesses walking distance in meters over a period of 6 minutes.	after up to 3 weeks of training
Timed Up and Go (TUG)	The TUG assesses mobility, balance, walking ability, and fall risk in older adults.	after up to 3 weeks of training
Orthotics Prosthetics User Survey (OPUS) Device Satisfaction	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.	after up to 3 weeks of training

Collaborators and Investigators

• Sponsor: Synchro Motion LLC
• Collaborators: Shirley Ryan AbilityLab

Study record dates

Study Major Dates

• Study Start (Actual): August 22, 2023
• Primary Completion (Actual): November 19, 2024
• Study Completion (Actual): December 19, 2024

Study Registration Dates

• First Submitted: July 3, 2023
• First Submitted That Met QC Criteria: July 18, 2023
• First Posted (Actual): July 21, 2023

Study Record Updates

• Last Update Posted (Estimated): July 1, 2025
• Last Update Submitted That Met QC Criteria: June 26, 2025
• Last Verified: June 1, 2025

More Information

Terms related to this study

• Keywords: Amputation; Transtibial; K2; Limited Community Ambulator
• Other Study ID Numbers: STU00217993

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No