Graded stiffness offloading insoles better redistribute heel plantar pressure to protect the diabetic neuropathic foot

Background: Diabetic heel ulceration is a common, detrimental, and costly complication of diabetes. This study investigates a novel graded-stiffness offloading method, which consists of a heel support with increasing levels of stiffness materials to better redistribute plantar pressure for heel ulcer prevention and treatment. Research question: Is the novel graded-stiffness solution better able to redistribute heel pressure and reduce focal stress concentration areas of the heel? Methods: Twenty healthy young men walked with four, 3D-printed, insole configurations. The configurations included the graded-stiffness insoles with and without an offloading hole under the heel tissue at risk for ul-cerations and two conventional offloading supports of flat insoles with no offloading and simple holed offloading insoles. In-shoe plantar pressure was measured using the Pedar-X system. Peak pressure and pressure dose were measured at three heel regions: offloaded region, perimeter of offloaded region, and periphery region. Results: The simple offloading configuration reduced pressure at the offloaded region; however, pressure at the perimeter of the offloading region significantly increased. With respect to ANOVA, the graded-stiffness off-loading configurations were more effective than existing tested solutions in reducing and redistributing heel peak pressure and pressure dose, considering all heel regions. Significance: The graded-stiffness offloading solution demonstrated a novel flexible and customized solution that can be manufactured on-demand through a precise selection of the graded-stiffness offloading location and material properties to fit the shape and size of the ulcer. This study is a follow-up in-vivo pilot study, in a healthy population group, to our previous computation modeling work that reported the efficiency of the graded-stiffness configuration, and which emphasizes its potential for streamlining and optimizing the prevention and treatment of diabetic heel ulcers.