Three-Spike Insole Can Substitute the Total Contact Insole (TCI) in Refractory Plantar Fasciitis: Randomized Control Trial

Abstract

Category: Hindfoot Introduction/Purpose: Plantar fasciitis is one of the common foot complaints that is chronic and can induce dysfunction. Approximately 80% of patients improve with conservative management such as stretching exercise, ice bag massage, and splint. Refractory plantar fasciitis, unresponsive to conservative care for more than 6months, can be treated with insole, extracorporeal shockwave therapy, injection, and surgery etc. Total contact insole (TCI) is effective in reducing pain with just putting it in the shoes but quite expensive and time consuming for the custom production. Therefore, we produced alternative three-spike insole that can press about half of patient’s plantar fascia using 3-dimensional (D) printing and compared the clinical outcomes with it and TCI. Methods: A pragmatic, participant-blinded randomized trial was carried out from February 2019 to January 2020. Inclusion criteria was refractory plantar fasciitis and the duration of follow-up for each patient was 6 months. Three-dimensional printing used thermoplastic polyurethane (TPU) for the material of insole and the hardness was 58 +- 5 Shore-A. Twenty-eight patients were randomly allocated to use a three-spike insole or a TCI (Figure 1). The following assessment tools were used; visual analog scale for pain, American Orthopaedic Foot & Ankle Society (AOFAS) score, Foot and Ankle Outcome Score (FAOS), Karlsson- Peterson (KP) score, Medical Outcomes Study Short Form-36 (SF-36) for quality of life, and Foot Function Index (FFI). The groups were evaluated by a blinded assessor at baseline and after 6, 12, and 24 weeks. Results: The groups were homogenous for the majority of variables at baseline. Overall patient reported satisfaction showed improvement from mean 5.2 (range, 1 - 12) weeks of wearing and patient’s wearing time in a day was mean 2.4 (range, 0.5 - 3.0) hours. All the subscales except for sports in FAOS and mental component summary in SF-36 showed significant improvement from 6 weeks in both groups. There was no significant difference in all parameters between both groups at 6 weeks but AOFAS score, some of FAOS subscales, KP score, SF-36, and FFI showed significantly better outcome in three-spike insole group at 12 weeks. Those significant differences in outcome parameters tended to diminish at 24 weeks. Conclusion: We reaffirmed that insole is effective in plantar fasciitis and showed the three-spike insole restores function rapidly comparing to TCI. Three-spike design that supports not the whole longitudinal arch but about half of it was efficient enough. We can manufacture the three-spike insole for the popularization that can lower the price and producing time.