Shear Load In-shoe Plantar Sensing/Strain Analyses and Mapping in Diabetic Foot Ulcers

Stain Analysis Mapping of the Plantar surface (STAMP) is a method designed by the University of Leeds to measure 'in-shoe' strain patterns on the plantar surface of the foot. Shear Load Inductive Plantar Sensing (SLIPS) is an insole designed by the University of Leeds to measure plantar shear stress and plantar pressure. This study aims to compare plantar strain using STAMP and plantar shear stress and plantar pressure using SLIPS in two groups of patients with diabetes; high risk patients with a recently healed plantar ulcer and low risk patients (according to the NICE definition).

Stain Analysis Mapping of the Plantar surface (STAMP) is a method designed by the University of Leeds to measure 'in-shoe' strain patterns on the plantar surface of the foot. The insole comprises a pseudorandom pattern applied to a plastically deformable insole using a temporary tattoo layer. STAMP utilises digital image correlation to track the deformation of the pattern following a period of walking.

Shear Load Inductive Plantar Sensing (SLIPS) is an insole designed by the University of Leeds to measure plantar shear stress and plantar pressure. SLIPS is an insole which integrates 64 tri-axis soft force sensors which simultaneously measures shear stress and pressure. The SLIPS insole has been designed to measure the plantar load of the right foot and due to its size can only be accommodated by a size 8-11 shoe.

The commercial device Pedar (Novel gmbh) will be used as a reference for plantar pressure measurement in both groups.

This study aims to compare plantar strain using STAMP and plantar shear stress and plantar pressure using SLIPS in two groups of patients with diabetes; high risk patients with a recently healed plantar ulcer and low risk patients (according to the NICE definition).

It is hypothesised that patients with a recently healed plantar ulcer with exhibit elevated plantar strain, plantar shear stress and plantar pressure than the low risk group.

Eligibility Criteria:
DFU group:

Patients will undergo STAMP and Pedar assessment if they fulfil the following criteria.

Inclusion Criteria:

1. Age \>18
2. A diagnosis of diabetes mellitus
3. A diagnosis of diabetic peripheral neuropathy
4. Recently healed plantar ulcer (within the last 3 months)
5. Able to provide informed consent
6. Previous open or endovascular revascularisation

SLIPS inclusion criteria:

Patients will also undergo assessment with the SLIPS insole if they fulfil the following inclusion criteria:

1. Recently healed plantar DFU located on the right foot
2. The right foot can be accommodated in a size 8-11 shoe
3. Weight \<100kg

Low risk group:

Patients will undergo STAMP and Pedar assessment if they fulfil the following criteria:

1. Age \>18
2. A diagnosis of diabetes mellitus
3. Low risk for DFU according to the NICE NG 19 guidelines (no risk factors for ulceration except callus alone)
4. Able to provide informed consent

Exclusion Criteria:

1. Unable to mobilise independently 150m without the use of walking aids and thus unable to complete the walking assessments
2. Previous ipsilateral minor amputation
3. Previous ipsilateral surgical offloading procedure
4. Previous contralateral major amputation
5. Ipsilateral toe pressure \<40mmHg

SLIPS assessment inclusion:

1. The right foot can be accommodated in a size 8-11 shoe
2. Weight \<100kg

Exclusion criteria:

1. Unable to mobilise independently 150m without the use of walking aids and thus unable to complete the walking assessments
2. Previous ipsilateral minor amputation
3. Presence of a foot deformity
4. Previous contralateral major amputation
5. Ipsilateral toe pressure \<40mmHg