Validation and reliability of mechanical stiffness assessment tools in multilayered polyurethane phantom models of healthy and diabetic plantar soft tissues.

Authors

Tülay Çevik Saldıran, Robert Schleip, Katja Bartsch, Wolfgang Bauermeister, Torsten Pohl, Thomas Horstmann

Published in

Scientific reports. Volume 15. Issue 1. Pages 34118. Sep 30, 2025. Epub Sep 30, 2025.

Abstract

Plantar soft tissue stiffness plays a crucial role in the development of diabetic foot complications, but in vivo assessments are constrained by anatomical variability and probe-induced measurement artifacts. To develop anatomically layered polyurethane phantom models mimicking healthy and diabetic plantar soft tissues and evaluate the reliability and concurrent validity of four mechanical stiffness assessment tools, [MyotonPRO, Shore Durometer, IndentoPRO, and Tissue Compliance Meter (TCM)] against Shear Wave Elastography (SWE). Six regional phantom models (calcaneus, midfoot, forefoot) with skin, fat pad, fascia, and muscle layers were fabricated. SWE was performed in no-contact mode to eliminate surface compression, improving measurement consistency. A total of 162 configurations were tested under blinded and randomized conditions. Intra- and inter-rater reliability was assessed using ICCs; concurrent validity was evaluated via correlation and regression analyses with SWE. All devices demonstrated excellent reliability (ICC range: 0.88-0.99). SWE-derived stiffness was significantly higher in diabetic models, especially in the calcaneal and midfoot regions (p < 0.001). IndentoPRO showed the highest correlation with SWE (r = 0.91), followed by MyotonPRO (r = 0.87), TCM (r = 0.85), and Durometer (r = 0.78). TCM exhibited the highest predictive value (R² = 0.502) and most consistent performance across diabetic regions. The developed phantom models offer a standardized platform for evaluating stiffness assessment tools. While SWE remains the reference standard, mechanical devices, particularly TCM and IndentoPRO, demonstrated valid and reproducible performance. This phantom-based approach holds promise for supporting medical device development, regulatory validation, and preclinical testing in diabetic foot biomechanics.

PMID:
41028165
Bibliographic data and abstract were imported from PubMed on 01 Oct 2025.

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