Authors (including presenting author) :
HO SH(1)
Affiliation :
(1)Prosthetic and Orthotic Department, Pamela Youde Nethersole Eastern Hospital
Introduction :
Rheumatoid arthritis(RA) is an autoimmune chronic inflammatory disease which would affect patients’ joints and cause progressive disability. RA may influence patients’ feet and as a result causes deformities and pain. Michelson et al (1994) found that 35% of the patients had at least one big toe with moderate to severe hallux valgus, more than 40% had hammer toes and 60% had flat foot. Another study pointed out that more than 60% and about 50% of the patients’ forefoot and toes would have frequent pain while about 40% of their ankles would have frequent pain during their disease course, female patients experience more severe pain than male patients (Otter et.al, 2010). RA may also affect patients walk gait and even cause foot ulcer by influencing circulatory system and plantar pressure distribution.
Objectives :
Orthotic therapy provides comprehensive care to patients’ feet. It had been proven that foot orthosis could significantly reduce foot pain and disability (Woodurn et al., 2002; Magalhaes et al., 2006). Orthotic insole could also improve patients’ gait (MacSween et al., 1999). However, there is lack of prescription guidelines for orthotic therapy. This review article aims to generate an evidence-based technical guideline by reviewing existing research and academic articles.
Methodology :
Almost 40 journal articles and book chapters were reviewed. Most of them were from Google Scholar while the book chapters were from the author’s own library. The searching key terms were rheumatoid arthritis, foot, pain, deformity, plantar pressure, gait, effect, effectiveness, recommendation, guideline, foot orthosis, orthosis, insole and so on.
Result & Outcome :
To systematically prescribe suitable foot orthoses to patients, it is necessary to classify the RA foot into different stages. RA foot could be divided to 3 stages (Baumgartner et al., 2016). For stage 1, foot function is limited but can be corrected actively during full weightbearing (FWB). For stage 2, foot function is deteriorated and can only be corrected during non-weightbearing (NWB), which means the deformities may be still flexible. For stage 3, the deformities are rigid and cannot be corrected. For the first 2 stages, since RA foot is still flexible, the orthotic treatment goal should be preventing further deformities by stabilizing patient’s heel and supporting foot arches. Custom semi-rigid functional foot orthosis or total contact rigid EVA insole may be the most suitable design. NWB casting method and subtalar neutral suspension technique should be used for RA foot with correctable heel valgus deformity (Woodburn et al., 2018). Foot orthosis which fabricated by this casting method together with semi-rigid materials could provide adequate arch support and control the subtalar joint. For stage 3 RA foot, the orthotic treatment goal should be accommodating and cushioning rigid deformities to redistribute abnormal plantar pressure. Custom moulded cushioning EVA foot orthosis may be most suitable. Since the RA patients with severe deformities could not tolerate rigid arch support, a flexible custom moulded EVA foot orthosis may be more suitable for them (Suhuch, 1988). Subtalar neutral cast should be taken in semi- weight bearing (SWB) with the patient seated by using impression foam. The orthotic insole with SWB foot shape may be more effective in reducing plantar pressure over 2nd and 3rd MT heads comparing with that with NWB foot shape and FWB foot shape (Tsung et al., 2004). Moreover, it is common that the fatty- fibro padding which originally located under metatarsal heads dorso-anteriorly displaces together with forefoot deformity in RA foot and thus plantar pressure over metatarsal heads would increase (Helliwell et al., 2006). It may cause forefoot pain so relieving forefoot pressure is important for almost all RA foot. Metatarsal pad should be used to transfer metatarsal pressure to the necks and shafts of the metatarsal bones (Kavlak et al., 2003), hence reducing forefoot pain (Kang et al., 2006).
