Fiber Bragg Grating Based Sensing'Platform for Foot Plantar Pressure Measurement

presented an application of using 3 D printing technique for the design and fabrication of a novel fiber Bragg grating( FBG)based sensing platform for foot planar pressure measurement.Pressure sensing unit was fabricated using 3 D printing technique by layering of extruded polylactic acid( PLA) material and mounting FBG sensor at the center of each sensing unit for pressure measurement. Performance of the sensing system was validated by applying load step by step as well as cyclic load on FBG pressure sensors. A simulation study was carried out using the sensing platform to assess foot plantar pressure distribution arises from weight gaining and losing processes of pregnant woman. The monitored four different foot positions such as first metatarsus,second metatarsus,mid-foot and heel exhibited obvious differences during testing process. Foot plantar pressure of heel was 1. 7 times of the pressure occurred at the first and second metatarsus( fore-foot),while there was limited pressure occurred at the mid-foot position during weight gaining process of a female subject. The occurred pressures at the two metatarsus areas were around 90%( pressure ratio) of heel and decreased continuously as the increase of subject weight,but weight losing process had very limited influence on this pressure ratio. Center of gravity of pregnant woman was found to shift backward substantially during the weighting gaining process,leading to a significant rise of the heel pressure. Hence, the protection of the heel position for female is highly important during both pregnancy and after baby delivery.

Negative pressure for diabetic foot:Evaluation based on calcitonin gene-related peptide in the limb skin of dogs

BACKGROUND: Very good therapeutic effect has been obtained for limb negative pressure in treating limb ischemic diseases. But its mechanism in treating diabetic foot needs further investigation. OBJECTIVE: To observe the changes of calcitonin gene related peptide (CGRP) in sensory nerve fiber of skin of dogs with diabetic foot before and after limb negative pressure treatment, and make a comparison with normal dogs, then analyze the mechanism of limb negative pressure in treating diabetic foot. DESIGN: A randomized controlled animal experiment. SETTING: Third Department of General Surgery, Xijing Hospital, Fourth Military Medical University of Chinese PLA. MATERIALS: Fifteen healthy hybrid dogs, of either gender, weighing 12-18 kg, were provided by Animal Room, Xijing Hospital of the Fourth Military Medical University of Chinese PLA. After being numbered, the involved dogs were randomly assigned into 3 groups: treatment group, model group and normal control group, 5 dogs each. Limb negative pressure therapeutic machine (self-made); Anti-CGRP serum (primary antibody, Watpa Company, England); rabbit anti-BigG (second antibody), ABC compound solution, DAB reagent, glucose oxidase reagent, Trixon-X100 solution (Sigma company, USA), ammonium nickelous sulfate reagent (Xi'an Chemical Reagent Factory), neutral gum-solution (import, Shanghai Reagent Co.,Ltd.); Leitz1400 sliding freezing microtome (Leitz Company, Germany); Leica1800 cryostat microtome (Leica Company, Germany); Quantimet570 image analyzer (Leica Company, Germany). METHODS: This experiment was carried out in the Animal Room, Xijing Hospital, Fourth Military Medical University of Chinese PLA from October 2005 to June 2006. ① After the dogs in the treatment and model groups were anesthetized, their pancreatic tissues were removed completely and animal models of type Ⅰ diabetes mellitus were developed. All the femoral artery branches including deep femoral artery were ligated and cut off. A helical wire was inserted into the distal femoral artery cavity for narrowing femoral artery 1/2, then contributing to ischemic status of this limb, thus, dog models of diabetic foot of posterior limbs were developed. When the dogs in the treatment group were successfully modeled, negative pressure treatment was conducted on their affected limbs after 14 days. When the dogs were lightly anesthetized, depilation was performed on the base of left posterior limb in ring form. Then, their depilated limbs were placed in self-made negative pressure cabin for 15 minutes of -12 kPa negative pressure treatment every day within 10 days successively. Negative pressure treatment on affected limbs was omitted in the model group. The dogs in the normal control group were not modeled or given negative pressure treatment. ②After 10 days of treatment, 3 groups of animals all subjected to immunohistochemical staining of toe skin of affected limb for detecting CGRP-immunoreactive positive nerve fibers. Analysis of variance and LSD-t test were used for comparison of measurement data. MAIN OUTCOME MEASURES: Changes of CGRP in sensory nerve fibers of skin of 3 groups of animals. RESULTS: CGRP-immunoreactive positive nerve fibers in the skin of animals of model group were (53.24±5.6) μm/mm2, which were significantly more than those of control group [(11.73±2.3) μm/mm2,t =16.94,P < 0.01]. CGRP-immunoreactive positive nerve fibers in the skin of animals of treatment group were (32.49±2.9) μm/mm2, which were less than those of model group (t =8.47,P < 0.01), but were still more than those of normal control group (t =8.47,P < 0.01). CONCLUSION: ① Following the onset of diabetic foot, CGRP-immunoreactive positive nerve fibers in the skin of distal limb are obviously increased, which may be a self-protective mechanism of body. ② Limb negative pressure treatment can treat diabetic foot, which attributes to that the release of CGRP in the sensory nerve fibers can promote vasodilatation.

Effects of Shoe Heel Height on Loading and Muscle Activity for Trans-Tibial Amputees During Standing

This study accesses the effects of shoe heel heights on loading, muscle activity, and plantar foot pressure of trans-tibial amputees during standing. Five male subjects with unilateral trans-tibial amputation volunteered to participate in this study. Three pairs of shoes with zero, 20 mm, and 40 mm heel heights were used. The loading line of the prosthetic side, the plantar foot pressure, and the surface electromyography （EMG） of 10 muscles were simultaneously recorded. With increasing shoe heel heights during standing, the loading line of the prosthetic side shifted from the anterior to the posterior side of the knee center, the peak pressure was increased in the medial forefoot region, and the peak pressure was reduced in the heel region. The EMG of the medial and lateral gastrocnemius of the sound leg almost doubled and that of the rectus fomris, vastus lateralis, and vastus medialis of the prosthetic side increased to different extents with in- creasing heel heights from zero to 40 mm. These results show a high correlation with human physical be- havior. Changing of the heel heights for trans-tibial amputees during standing actually had similar effects to altering the prosthetic sagittal alignment. The results suggest that an alignment change is necessary to accommodate heel height changes and that prosthesis users should be cautious when choosing shoes.