Foot-specific exercise intervention for forefoot deformity in individuals with type 2 diabetes and peripheral neuropathy: A randomized controlled clinical trial with 3-year follow-up

Background Diabetes with peripheral neuropathy can lead to metatarsophalangeal joint (MTPJ) deformity. The purpose of this study was to estimate the effect of a foot-specific intervention on MTPJ deformity. Secondary aims were determining MTPJ deformity progression over 3 years and predictors of MTPJ deformity progression. Methods Sixty people with type 2 diabetes and peripheral neuropathy were recruited for this randomized controlled clinical trial. Participants were assessed at baseline, 6 months (post-intervention), 1.5 years, and 3 years. A 6-month, foot-specific intervention in the experimental group was compared to a shoulder intervention in the control group. The primary outcome was change in 2nd MTPJ angle assessed with computed tomography (CT). Results There was no effect of intervention on 2nd MTPJ angle (main effect of group p = 0.56, main effect of visit p = 0.56, group*visit interaction p = 0.79). In combined experimental and control groups, 26 % and 9 % of participants met the cutoff threshold for MTPJ angle progression at 1.5 and 3 years, respectively. Change in 2nd metatarsal bone mineral density from baseline to 3 years predicted 2nd MTPJ angle progression at 3 years (Rescaled R² = 0.22, p = 0.01). Conclusion The study intervention was unable to yield a detectible improvement in 2nd MTPJ angle. The intervention may not have been of sufficient intensity to induce positive changes or there may be limited capacity for the neuropathic foot to respond to traditional modes of exercise. While useful in improving other outcomes, exercise-based intervention may not be an effective method of reducing or delaying forefoot deformity progression.