Biomechanical and functional alterations in the diabetic foot: Differences between type I and type II Diabetes

Introduction: Biomechanical alterations in the diabetic foot have been studied for decades, and are still under discussion [1]. In particular, an agreement is far to be reached in terms of a comprehensive, clinically relevant biomechanical model of foot segments loading during locomotion [2]. In order to get a better insight into this topic, a wide study has been designed and conducted which relies on an integrated pressure – kinematic methodology [3]. Main aim of the study is to detect and quantify the impact of Diabetesassociated modifications of foot function by isolating the role of each possible confounding factor. In this preliminary study we investigated the role of type I and type II Diabetes, while strictly controlling the remaining relevant biological and clinical variables. Methods: From January 2016, a wide sample of diabetic patients and healthy volunteers was examined through an integrated pressure-kinematic technique based on the Rizzoli Foot Model and five foot regions of interest [3,4]. At present, 140 participants have been enrolled and acquired under controlled, self-selected cadence. Five consistent trials have been collected for each foot. Patients were clinically stratified based on type I or type II Diabetes and, within each type, grouped according to: presence/absence of neuropathy; presence/absence of deformities or functional limitations; BMI; age; walking cadence. This preliminary combined study on pressure and kinematics was conducted on a sample of 30 feet, equally distributed among three subgroups: diabetics type I (T1), diabetics type II (T2), and age-matched healthy controls (C). For all subjects, walking cadence was in the range 50–55 spm, BMI was <30 kg/m2, deformity or functional limitation and Neuropathy were absent. Based on previous correlation studies [4], the range of motion (RoM, degrees) of the ankle joint in the frontal plane was selected as the relevant kinematic variable. Pressuretime integral (PTI, kPa*s) was used to investigate loading under the total foot and the five regions of interest. 1-way ANOVA (p < 0.05) with Bonferroni-Holm correction was applied to all parameters and groups. Results: T1 (who only differed from C for the presence of long-term Diabetes), with respect to C, showed a significant shift of loading from midfoot and forefoot to toes (T1, respectively: 19.2±7.4, 104.3±38.3, 47.0±29.3; C: 24.1±10.1, 118.9±26.3, 34.1±20.8), associated with a moderate – albeit not statistically significant – RoM reduction (T1: 6.9±2.4; C: 7.6±2.4). T2, with respect to C,showedsignificant changes in forefoot and toes loading (T2: 150.4±63.3, 28.4±15.6) and a significant ankle RoM reduction (6.0±1.2) likely due to Diabetes but also in possible association with older age. Further, T2 (61.0±14.2) significantly differed from T1 (69.6±17.2) for the lower loading at hindfoot. Lower loading was observed also at the toes, and higher loading at the forefoot. Discussion: The present results show that the Diabetes type alone, i.e. without neuropathy or deformity complications, is responsible for major biomechanical changes of foot function in the stance phase of walking.