Functionally Optimized Orthoses for Early Rheumatoid Arthritis Foot Disease: A Study of Mechanisms and Patient Experience

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.