DPN Diabetes Foot Ulcer Risk And Foot Orthosis Design

With the rapid development of the national economy,people’s diet contains a lot of foods with high fat and high sugar.Lack of physical activity in work and life leads to a rapid increase in the number of diabetic patients.Diabetic foot is one of the most common long-term complications of diabetes.It often causes foot ulcers and even lower extremity amputation.Studies have shown that deep soft tissue deformation is an important cause of diabetic foot ulcers,and the finite element biomechanical model can be used to analyze the loading and stress state of human tissue in detail.At the same time,personalized customized insoles have been gradually used in the prevention and rehabilitation of many foot and ankle related diseases,and have become the focus of attention in the field of medical and health care.Therefore,we investigated the potential relationship between the above factors and the initial occurrence of ulcers by investigating the differences in the characteristics of the soft tissue and the main muscles of the lower extremities in patients with DPN(peripheral neuropathic diabetes)and DM(without peripheral neuropathic diabetes).It provides a theoretical basis for the prediction of ulcer risk and the design of rehabilitation devices for foot orthosis.The main research work is as follows:(1)Based on ultrasound elastography,the differences of soft tissue characteristics in plantar tissues and muscles between DPN group(26 cases),DM group(28 cases)and diabetic group(27 cases)were studied.The measured tissues include heel,midfoot,second metatarsal head,fifth metatarsal head,plantar tissue of big toe,plantar fascia and main muscles of lower leg.The results showed that there was no significant difference in the thickness of plantar soft tissue between DPN group and healthy group.The plantar soft tissue in DPN group was softer than that in healthy group and DM group;The experimental results of plantar fascia showed that the stiffness and thickness of plantar fascia in DPN group and DM group were higher than those in healthy group;The experimental results of lower limb muscles showed that compared with the lower limb muscle characteristics of DM,the elastic modulus of abductor muscle in DPN patients decreased,and the cross-sectional area of abductor muscle also decreased significantly(P < 0.001).(2)Based on the hall model of human lower limb established by the research group in the early stage,the typical lower limb foot and ankle models of DPN,DM and normal people were constructed by coupling the geometric personalization of soft tissue materials and anatomical structure,and the dynamic gait simulation was carried out to compare and analyze the difference of biomechanical response between the three groups of models.The results show that only in terms of changing the stiffness of plantar soft tissue,the peak plantar pressure of DPN group is lower than that of normal group in the five stages of gait process in the process of right foot support,and the maximum deviation is 9.5%.This trend also appears in the comparison of peak plantar pressure between DPN group and DM group.Compared with healthy subjects,the strain of deep soft tissue in the four important areas concerned by DPN patient model is greater,and the maximum deviation is 16.4%;The same difference is also reflected in the comparison between DM patient model and DPN patient model.(3)In view of the abnormal pressure center line of diabetes patients,a bionic fishbone orthosis was designed based on the gait pressure line correction principle.The effectiveness of the fishbone orthosis was evaluated by biomechanical model.Finally,a small batch of insoles was produced through 3D printing,and its effectiveness was evaluated based on volunteer experiments.The results show that the bionic fishbone foot orthosis can correct the angle between the coronal plane of calcaneus and the ground to varying degrees,up to 11 ° and achieve 93% correction;The plantar contact area can be corrected up to 45% through the supported arch;The peak plantar pressure decreased by 64%.After wearing foot orthosis,the plantar pressure distribution of patients also tended to the healthy population.To sum up,this paper explores the differences of plantar soft tissue characteristics and muscle characteristics among DPN patients,DM patients and healthy people,and analyzes the effects of plantar soft tissue differences on foot ankle dynamic response,especially plantar pressure and deep soft tissue strain.Finally,a small batch of first generation bionic fish bone foot orthosis is designed,analyzed and manufactured based on the correction and reduction of plantar pressure based on the pressure centerline,The rationality and effectiveness of the design are verified by volunteer experiments.This study provides a theoretical basis for risk prediction,prevention and rehabilitation of diabetic foot ulcers.