Design and pilot testing of the DVA/Seattle Footwear System for diabetic patients with foot insensitivity

Clinical epidemiology studies suggest the majority of lower limb amputations were preceded by a minor traumatic event, often footwear-related, and lower limb ulcers. To reduce foot trauma and ulcers, the diabetic patient with foot insensitivity has unique footwear needs. To address these needs for patients not requiring custom shoes, the DVA/Seattle Footwear System was developed. The six components of this system include: 1) a specially designed shoe last based on the geometry of the diabetic foot and research findings on foot regions at highest risk of ulceration, 2) a depth-inlay shoe, "Custom Stride by PRS," designed to be paired with either a custom-fabricated cork insole or a preformed polyurethane insole, 3) a laser digitizing system that captures 3-D plantar foot contours, 4) DVA/Seattle ShapeMaker software adaptation for modifying plantar surface contours and applying free-form and template modifications to increase or relieve loading, 5) software that translates files into code used by a milling machine to define the cutting path and carve cork blockers into custom insoles, and 6) a preformed polyurethane insole thicker than a typical insole to accommodate the extra volume and the interior dimensions of the shoe. A 6-month pilot cross-over trial of 24 diabetic male veterans without prior foot ulcers was conducted to determine the feasibility of producing, and the safety of wearing, these depthinlay shoes and both types of insoles. During the first 4 weeks, patients were assigned to the study shoes and one type of insole. During the next 4 weeks, they wore the other type of insole, and during the final 4 months, they chose which pair of insoles to wear with the study shoes. Over 150 person-months of footwear observation revealed no breaks in the cutaneous barrier with use of either cork or polyurethane insoles and the study shoes. Patient compliance with the footwear was 88%. Patients were highly satisfied with the appearance, stability, and comfort of the shoes and the comfort of both types of insole. However, 75% of the patients noted that the study shoes felt heavier than their customary shoes. Further research is needed to determine the long-term effectiveness of footwear in prevention of foot ulcers in the population at highest risk for diabetic reulceration and amputation.