New-Design Orthotic Footwear for Tactile Stimulation: A Pilot Study on Two Distinct Stimuli

Abstract

Diabetic peripheral neuropathy (DPN) causes tactile impairment and leads to foot ulcers and lower limb disabilities. Reducing vibration perception threshold (VPT) and preventing foot ulceration are recommended goals of tactile enhancement for DPN. In this study, a new-design vibrational foot orthosis (VFO) with a novel vibratory stimulus, a square wave pulse integrated with pseudorandom noise (PRN) via a stochastic resonance (SR) technique, was developed to improve tactile sensitivity. A pilot study was conducted to investigate the effectiveness of using the VFO for tactile stimulation in twenty DPN patients with two distinct interventions: 1) a 100 Hz square wave pulse stimulus combined with PRN by a SR technique; and 2) a random 0-100 Hz square wave pulse stimulus combined with PRN by a SR technique. VPT values at the 1st metatarsophalangeal joint (MTP) and 5th MTP were assessed in a pretest and posttest as the outcome. The results indicated that both interventions could significantly decrease VPT values (P<.001); however, intervention 2 might effectively lower VPT values more than intervention 1 by around threefold. In conclusion, the VFO can improve tactile sensitivity, particularly the random stimulus mixed with PRN by a SR technique, which may provide a greater advantage than no random stimulus. The VFO can address the challenges of a total contact design, appropriate manufacturing for diabetic feet, and fabrication with medical-grade materials. Contributions: The VFO may be useful for neurorehabilitation, avoiding foot ulcers and their recurrence, as well as preventing lower limb amputation.