Functionally Optimized Orthoses for Early Rheumatoid Arthritis Foot Disease: A Study of Mechanisms and Patient Experience KELLIE S. GIBSON, 1 JAMES WOODBURN, 1 DUNCAN PORTER, 2 AND SCOTT TELFER 1 Objective. To investigate the mode-of-action and patient experience of functionally optimized foot orthoses in patients with early rheumatoid arthritis (RA). Methods. We conducted an investigation of 2 functionally optimized foot orthoses (selective laser sintering [SLS] and fused deposition modelling [FDM]) in 15 patients with RA of <2 years duration. The novel devices were optimized for 3 biomechanistic targets exploiting computer-aided design and additive manufacturing. A third standard device was used as the comparator (standard foot orthosis [SFO]). Foot and ankle biomechanical effects were compared. Adverse reactions, orthotic fit and comfort, and short-term symptom benefits were also monitored. Results. Both FDM (P  0.028) and SLS (P < 0.0001) orthoses significantly reduced peak rearfoot motion in comparison to shod. The average ankle internal moment was significantly decreased in the SFO (P  0.010) and approached significance in the SLS (P  0.052) orthosis. SFO, FDM, and SLS orthoses significantly increased the peak height of the medial foot arch between 3.6 to 4.4 mm (P < 0.001). Peak pressures in the medial (P  0.018) and lateral forefoot (P  0.022) regions of interest were significantly reduced for the SLS orthosis. SFO, FDM, and SLS orthoses significantly increased midfoot contact area (P < 0.001 for all conditions). In comparison to SFO, SLS and FDM orthoses provided equivalent or better patient experience. No adverse reactions were reported. Conclusion. Functional optimization is a feasible approach for orthoses prescription in early RA and has the potential to provide superior mode-of-action responses for biomechanical therapeutic targets compared to standard devices. INTRODUCTION There is a high prevalence of foot involvement in early rheumatoid arthritis (RA), with up to 70% of patients reporting pain and swelling in at least 1 metatarsophalan- geal (MTP) joint and 60% reporting walking disability (1,2). Consequently, there have been calls for nonpharma- cologic treatments such as orthotics to be targeted earlier in the course of the disease (3,4). Custom foot orthoses have been designed to conform to individual foot shape to redistribute load from weight-bearing sites, particularly painful MTP joints (5,6). Active peritalar disease is asso- ciated with acquired pes plano valgus and there is evi- dence this can occur early in RA (7). Here custom orthoses have been prescribed to correct the medial longitudinal arch shape and control subtalar and midtarsal joint motion and forces (8,9). Our recent systematic review and meta- analyses indicated that custom foot orthoses may be ben- eficial in reducing pain and elevated forefoot pressures (10). Furthermore, van der Leeden et al (11) suggest that greater improvements in self-reported foot pain and dis- ability can be achieved in younger patients with shorter disease duration when there is less irreversible joint dam- age and foot deformity (11). However, definitive studies are lacking and further research is required (3,10,12). We have recently developed viable, mechanically based therapeutic targets by translating discoveries in fundamen- tal biomechanics associated with RA foot and ankle im- pairments to orthotic design rules (13,14). Against these targets we have developed novel, functionally optimized foot orthoses, the design of which is objectively deter- mined based on instrumented analysis of the patient’s gait, as opposed to traditional subjective approaches. These novel devices exploit new capabilities in computer-aided design and additive manufacturing (3-dimensional [3-D] printing) (15,16). Additive manufacturing offers geometric design freedom and accurate control of manufacturing stages over a range of platforms varying in scale, cost, and Supported by the European Commission Framework Seven Program (grant NMP2-SE-2009-228893) as part of the A-FOOTPRINT Project (www.afootprint.eu). 1 Kellie S. Gibson, PhD (current address: University of East London, London, UK), James Woodburn, PhD, Scott Telfer, EngD: Glasgow Caledonian University, Glasgow, UK; 2 Duncan Porter, MD: University of Glasgow, Glasgow, UK. Address correspondence to Scott Telfer, EngD, Glasgow Caledonian University, School of Health and Life Sciences, 70 Cowcaddens Road, Glasgow, Scotland G4 OBA, United Kingdom. E-mail: scott.telfer@gcu.ac.uk. Submitted for publication April 22, 2013; accepted in revised form June 3, 2013. Arthritis Care & Research Vol. 66, No. 10, October 2014, pp 1456 –1464 DOI 10.1002/acr.22060 © 2014, American College of Rheumatology ORIGINAL ARTICLE 1456