Pressure Alternating Shoes (PAS)

Pressure Alternating Shoes (PAS) for Prevention of Diabetic Foot Ulcers

The project is designed to develop and test Pressure Alternating Shoes (PAS), which will periodically off-load certain regions of the foot in order to prevent foot ulcers. An automated dual layer insole compromised of an active pressurized actuator array in combination with a passive compliant layer on top of each actuator to modulate and distribute the plantar surface pressure as desired will be tested. This device will allow us to simultaneously load and offload select areas of the foot using the active layer by inflating and deflating individual actuators using pressurized air. After offloading, the remaining load will be distributed to other areas with inflated actuators. Automatic modulation will be provided through programmable control hardware which will cyclically relieve mechanical loading based on a prescribed duration and frequency.

Study Overview

• Status: Completed
• Conditions: Foot Ulcer, Diabetic
• Intervention / Treatment: Device: test pressure alternating shoes

Detailed Description

The two-tier human subjects study will be conducted to assess the biomechanical characteristics of PAS. In the first tier, we will test PAS in healthy subjects and in the second tier, we will test PAS in Diabetic Neuropathy patients (DN).

Subjects will walk on a treadmill in their usual daily shoes for 5 minutes, then with standard diabetic shoes with the PAS insoles for 5 minutes. Subjects will wear body worn sensors that assess position of the body. Subjects will have the temperature of their feet measured via a special camera after walking. Subjects will rest for 30 minute washout period and have the blood flow in the soles of the feet measured via a special camera. 1 healthy subject will undergo MRI of the foot and ankle.

• Study Type: Interventional
• Enrollment (Actual): 21
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Texas
    • Dallas, Texas, United States, 75390-8560
      • University of Texas Southwestern Medical Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Study Population

1. Healthy controls
2. Patients with Diabetic Neuropathy

Description

Healthy Controls:

Inclusion Criteria:

• Age 18 or greater
• Ability to wear insoles in shoes provided
• Ability to walk unaided

Exclusion Criteria:

• Diabetic Neuropathy
• Charcot foot
• Knee pain
• Previous amputations
• Inflammatory diseases such as rheumatoid arthritis
• Open wounds, ulcers, sores or blisters on the feet; signs of infection in the feet

Diabetic population:

Inclusion:

• Age 18 or greater
• Ability to wear insoles in shoes provided
• Ability to walk unaided
• Diagnosis of diabetic neuropathy

Excluision:

• Charcot foot
• Knee Pain
• Previous amputations
• Inflammatory diseases such as rheumatoid arthritis
• Open wounds, ulcers, sores or blistesr on the feet; signs of infection in the feet

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Healthy controls; Patients without diabetes who do not have foot wounds or history of amputation	Device: test pressure alternating shoes; test pressure alternating shoes
Experimental: Patients with Diabetic Neuropathy; Patients with diagnosed diabetes and neuropathy who do not have foot wounds or history of amputation.	Device: test pressure alternating shoes; test pressure alternating shoes

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximum Average Pressure at Baseline With Pressure Alternating Shoes, Right Foot (Before Any Cells Were Offloaded)	Maximum Average pressure values in the plantar regions before offloading during walking. The insole consists of seven air cells that align with specific regions: the big toe (cell 1), the area spanning from the second toe to the fifth toe (cell 2), metatarsal heads (cells 3 and 4), the midfoot (cells 5 and 6), and the heel (cell 7). Measurements were only obtained from the right foot.	Before any cells were offloaded (First 40-seconds of the walk)
Maximum Average Pressure at After Offloading - Diabetic Footwear Equipped With PAS Device	Maximum Average pressure values in the plantar regions after offloading cells during walking. The insole consists of seven air cells that align with specific regions: the big toe (cell 1), the area spanning from the second toe to the fifth toe (cell 2), metatarsal heads (cells 3 and 4), the midfoot (cells 5 and 6), and the heel (cell 7). Measurements were only obtained from the right foot. The results reported represent results for footwear with PAS device.	After offloading (approx. 41- 200 seconds walk)
Peak Interface Pressure at Baseline (Before Offloading) - Diabetic Footwear Equipped With PAS Device	Peak Interface Pressure values in the plantar regions before offloading during walking. The insole consists of seven air cells that align with specific regions: the big toe (cell 1), the area spanning from the second toe to the fifth toe (cell 2), metatarsal heads (cells 3 and 4), the midfoot (cells 5 and 6), and the heel (cell 7). Measurements were only obtained from the right foot. The results reported represent results for footwear with PAS device.	Baseline (First 40-seconds of the walk)
Peak Interface Pressure at After Offloading - Diabetic Footwear Equipped With PAS Device	Peak Interface Pressure values in the plantar regions after offloading during walking. The insole consists of seven air cells that align with specific regions: the big toe (cell 1), the area spanning from the second toe to the fifth toe (cell 2), metatarsal heads (cells 3 and 4), the midfoot (cells 5 and 6), and the heel (cell 7). Measurements were only obtained from the right foot. The results reported represent results for footwear with PAS device.	After offloading (approx. 41- 200 seconds walk)
Max Average Pressure Change Among All Participants - Diabetic Footwear Equipped With PAS Device	Percentage change due to offloading for each participant is measured by dividing the pressure difference between the after offloading and before offloading values divided by the before offloading value. Measurements were only obtained from the right foot. The results reported represent results for footwear with PAS device.	Baseline (first 40-second walk), 201 seconds after the intervention ended
Peak Pressure Change Among All Participants - Diabetic Footwear Equipped With PAS Device	Peak pressure change due to offloading for each participant is measured by dividing the pressure difference between the peak after offloading and peak before offloading values divided by the peak before offloading value. Measurements were only obtained from the right foot. The results reported represent results for footwear with PAS device.	Baseline (first 40-second walk), 201 seconds after the intervention ended

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Balance	Positional sense measured by body-worn sensors (cm)	Baseline
Plantar Skin Temperature at Baseline, Right Foot	Plantar skin temperature measured by a noncontact thermal imaging camera (*Celcius) before the intervention and without footwear	Baseline before the intervention (30 minutes after start of visit 1)
Plantar Skin Temperature Post Intervention, Right Foot	Plantar skin temperature measured by a noncontact thermal imaging camera (*Celcius) post intervention, without footwear	Post intervention (215 seconds)
Tissue Oxygenation (Oxygen Saturation) - for Plantar Lateral Foot	Plantar foot tissue oxygenation (Oxygen saturation) is measured by noncontact hyperspectral imaging camera (StO2). Only the right foot was analyzed and without footwear.	Baseline (30 minutes after start of visit 1)
Tissue Oxygenation (Oxyhemoglobin and Deoxyhemoglobin ) - for Plantar Lateral Foot	Plantar foot tissue oxygenation (Oxyhemoglobin and Deoxyhemoglobin) is measured by noncontact hyperspectral imaging (HSI) camera. Only the right foot was analyzed and without footwear. The accepted measure of oxyhemoglobin and deoxyhemoglobin is arbitrary units (AU). NIR spectrum light passes through skin and is reflected off the blood supplying the tissue. Wavelength dependent light absorption of hemoglobin differs if it is carrying oxygen or not, therefore detecting oxygenated and deoxygenated blood. This was derived from Beer-Lambert Law but would need to be verified by the manufacturer. There is no researcher drawn calculation as the device provides the arbitrary unit based on the reflectance detected back to the imaging device. No reference values or any standardization available but one would infer higher oxyhemoglobin level indicates better oxygenation and thus a higher deoxyhemoglobin would be indicative of poor oxygenation.	Baseline (30 minutes after start of visit 1)
Tissue Oxygenation (Oxygen Saturation) - for Plantar Medial Foot	Plantar Medial foot tissue oxygenation (Oxygen saturation) is measured by noncontact hyperspectral imaging camera (StO2). Only the right foot was analyzed and without footwear.	Baseline (30 minutes after start of visit 1)
Tissue Oxygenation (Oxyhemoglobin and Deoxyhemoglobin) - for Plantar Medial Foot	Plantar medial foot tissue oxygenation (Oxyhemoglobin and Deoxyhemoglobin) is measured by noncontact hyperspectral imaging (HSI) camera. Only the right foot was analyzed. Only the right foot was analyzed and without footwear. The accepted measure of oxyhemoglobin and deoxyhemoglobin is arbitrary units (AU). NIR spectrum light passes through skin and is reflected off the blood supplying the tissue. Wavelength dependent light absorption of hemoglobin differs if it is carrying oxygen or not, therefore detecting oxygenated and deoxygenated blood. This was derived from Beer-Lambert Law but would need to be verified by the manufacturer. There is no researcher drawn calculation as the device provides the arbitrary unit based on the reflectance detected back to the imaging device. No reference values or any standardization available but one would infer higher oxyhemoglobin level indicates better oxygenation and thus a higher deoxyhemoglobin would be indicative of poor oxygenation.	Baseline (30 minutes after start of visit 1)
Tissue Oxygenation (Oxygen Saturation) - for Plantar Lateral Foot	Plantar foot tissue oxygenation (Oxygen saturation) is measured by noncontact hyperspectral imaging camera (StO2). Only the right foot was analyzed and without footwear.	Post Gait (approx. 2015 seconds post intervention)
Tissue Oxygenation (Oxyhemoglobin and Deoxyhemoglobin ) - for Plantar Lateral Foot	Plantar foot tissue oxygenation (Oxyhemoglobin and Deoxyhemoglobin) is measured by noncontact hyperspectral imaging (HSI) camera. Only the right foot was analyzed and without footwear. The accepted measure of oxyhemoglobin and deoxyhemoglobin is arbitrary units (AU). NIR spectrum light passes through skin and is reflected off the blood supplying the tissue. Wavelength dependent light absorption of hemoglobin differs if it is carrying oxygen or not, therefore detecting oxygenated and deoxygenated blood. This was derived from Beer-Lambert Law but would need to be verified by the manufacturer. There is no researcher drawn calculation as the device provides the arbitrary unit based on the reflectance detected back to the imaging device. No reference values or any standardization available but one would infer higher oxyhemoglobin level indicates better oxygenation and thus a higher deoxyhemoglobin would be indicative of poor oxygenation.	Post Gait (approx. 2015 seconds post intervention)
Tissue Oxygenation (Oxygen Saturation) - for Plantar Medial Foot	Plantar Medial foot tissue oxygenation (Oxygen saturation) is measured by noncontact hyperspectral imaging camera (StO2). Only the right foot was analyzed and without footwear.	Post Gait (approx. 2015 seconds post intervention)
Tissue Oxygenation (Oxyhemoglobin and Deoxyhemoglobin) - for Plantar Medial Foot	Plantar medial foot tissue oxygenation (Oxyhemoglobin and Deoxyhemoglobin) is measured by noncontact hyperspectral imaging (HSI) camera. Only the right foot was analyzed and without footwear. The accepted measure of oxyhemoglobin and deoxyhemoglobin is arbitrary units (AU). NIR spectrum light passes through skin and is reflected off the blood supplying the tissue. Wavelength dependent light absorption of hemoglobin differs if it is carrying oxygen or not, therefore detecting oxygenated and deoxygenated blood. This was derived from Beer-Lambert Law but would need to be verified by the manufacturer. There is no researcher drawn calculation as the device provides the arbitrary unit based on the reflectance detected back to the imaging device. No reference values or any standardization available but one would infer higher oxyhemoglobin level indicates better oxygenation and thus a higher deoxyhemoglobin would be indicative of poor oxygenation.	Post Gait (approx. 2015 seconds post intervention)

Collaborators and Investigators

• Sponsor: University of Texas Southwestern Medical Center
• Collaborators: National Institute on Aging (NIA); The University of Texas at Arlington
• Investigators: Principal Investigator: Peter Crisologo, D.P.M., UT Southwestern Medical Center

Study record dates

Study Major Dates

• Study Start (Actual): March 7, 2024
• Primary Completion (Actual): July 11, 2024
• Study Completion (Actual): July 11, 2024

Study Registration Dates

• First Submitted: August 25, 2023
• First Submitted That Met QC Criteria: September 6, 2023
• First Posted (Actual): September 7, 2023

Study Record Updates

• Last Update Posted (Actual): August 12, 2025
• Last Update Submitted That Met QC Criteria: July 23, 2025
• Last Verified: July 1, 2025

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Endocrine System Diseases; Vascular Diseases; Cardiovascular Diseases; Diabetes Mellitus; Diabetic Angiopathies; Diabetes Complications; Skin Diseases; Skin Ulcer; Leg Ulcer; Diabetic Neuropathies; Foot Diseases; Diabetic Foot; Foot Ulcer
• Other Study ID Numbers: STU-2022-1038; 7R21AG061471-02 (U.S. NIH Grant/Contract)

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: Yes
• product manufactured in and exported from the U.S.: No