Biomechanical Efficacy of Shear-Reducing Diabetic Insoles: Elaborations on Future Design Criteria. Issue 2 (April 2019)

• Record Type: Journal Article
• Authors: Yavuz, Metin; Ersen, Ali; Richardson, Mike; Adams, Linda S.; Holmes, Clayton F.; Wijesundara, Muthu B.J.; Wukich, Dane K.; La Fontaine, Javier
• Is Part Of: Journal of prosthetics and orthotics. Volume 31:Issue 2(2019)
• Publication Date: 2019-04
• Subjects: diabetic insoles -- shear-reducing insoles -- diabetic foot ulcers -- plantar shear -- diabetic foot; Prosthesis -- Periodicals; Orthopedic apparatus -- Periodicals; 617.58
• DOI: 10.1097/JPO.0000000000000241
• Languages: English
• ISSNs: 1040-8800

Abstract

ABSTRACT: Introduction: Increasing evidence suggests that plantar shear forces and related stresses play a major role in diabetic foot ulcerations. Several orthotic devices are commercially available to reduce plantar shear forces within the shoe. The biomechanical efficacy of these devices was not tested in vivo. To measure spatiotemporal characteristics of gait to assess the efficacy of such shear-reducing insoles (SRIs), control insoles were also tested for comparison purposes. Material and Methods: Eighteen healthy volunteers walked along a 30.5-m line while wearing three types of insoles in randomized order. Spatiotemporal parameters of gait were quantified. Statistical comparisons between the control and SRIs were conducted using repeated measures analysis of variance. Intraclass correlation coefficients (ICCs) were also calculated to reveal the repeatability of the trials. Step length, gait speed, and cadence of the subjects remained similar regardless of the insole type. Results: No significant difference was observed in any variable. The ICC values revealed excellent repeatability. Conclusions: The lack of changes in gait parameters in these results suggest that shear-reducing diabetic inserts did not decrease plantar shear forces as intended. This might be caused by unrealistic in vitro testing conditions during the prototype development. Future designs should also consider friction at the lateral walls of the inserts, an increase in step repetition that accompanies a decrease in gait speed and/or step length, and a possible temperature increase within the shoe. We conclude that the future SRIs need to be redesigned based on comprehensive biomechanical guidelines.