Prospective Cohort Validation Study of a Novel Foot Offloading Device

Abstract

Pressure offloading is often considered a crucial factor affecting healing after a foot injury. We have devised a novel foot offloading device (PopSole) which allows for immediate customization of the area where there is foot pain and allows for adjustable arch support and metatarsal pad height while maintaining patient stability. We hypothesize that pain and function outcomes will improve significantly after use of the device over a 1-month period. Ten participants with foot pain for longer than 6 months completed five validated outcome questionnaires during three visits (initial screening, at 2 weeks, and at 4 weeks). Devices were deflated in areas of pain specific for each patient. Validated patient reported outcomes measures showed significant improvement in pain and function from baseline to week two (r = 0.644, P < 0.05), (r = 0.43, P < 0.05), and (r = 0.552, P < 0.05), respectively, and the Foot & Ankle Ability Measure (FAAM) showed improved ability in activities of daily living (r = 0.58, P < 0.05) and sports (r = 0.69, P < 0.05). All 10 patients reported pain relief during at least one visit and/or an ability to return to standing-based activities that they previously were unable to do. PopSole rapidly improved pain and function, with sustained relief through 4 weeks. Current studies are in progress to assess long-term durability of the device and potential modifications to be made before future randomized studies to assess pressure and gait assessment, shear forces, and diabetic foot ulcer mitigation.

Copyright © 2021 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of The American Society of Plastic Surgeons.

Figures

Fig. 1.

Validated patient reported outcome measure results. A, Foot and Ankle Ability Measure. FAAM responses to a variety of specified activities ranging from “no difficulty” to “unable to do.” A lower score indicated improved ability to perform ADLs and sports (r = 0.58, P < 0.0001 and r = 0.69, P < 0.0001), respectively. B, Mayo Pain Score and Manchester Foot Pain and Disability Index. Mayo Questionnaire Pain Score ranged from 0 (minimum) to 100 (maximum). Duration and intensity of pain, activity limitations, orthotic requirements, antalgic gait, neuropathy, and plantar heel tenderness are all graded and summated. Higher scores indicated improved pain and fewer limitations (r = 0.64, P = 0.002 from baseline to week 2). MFPDI responses to a variety of pain and specified activities ranging from “on most/every day(s)” to “none of the time.” Scores were surveyed at each time point where a lower score indicated improved functionality, pain, appearance, and work/leisure activities (r = 0.55, P = 0.0003).

Fig. 2.

The PopSole Device. A, Photograph of a PopSole device (at screening) for a 37-year-old female patient with central forefoot and heel pain for several years. She has been treated for neuromas with steroid injections and has failed conservative management with orthotic devices. The PopSole was fitted to her foot and bubbles were popped under the metatarsal’s heads and heel. B, Photograph of the same patient’s PopSole device at the 1-month check-in, demonstrating some unintended bubble deflation surrounding the bubbles that were initially popped, most notably in the heel area.