G. Guarneri

Integrated kinematics-kinetics-plantar pressure data analysis: A useful tool for characterizing diabetic foot biomechanics

The fundamental cause of lower-extremity complications in diabetes is chronic hyperglycemia leading to diabetic foot ulcer pathology. While the relationship between abnormal plantar pressure distribution and plantar ulcers has been widely investigated, little is known about the role of shear stress. Moreover, the mutual relationship among plantar pressure, shear stress, and abnormal kinematics in the etiology of diabetic foot has not been established. This lack of knowledge is determined by the lack of commercially available instruments which allow such a complex analysis. This study aims to develop a method for the simultaneous assessment of kinematics, kinetics, and plantar pressure on foot subareas of diabetic subjects by means of combining three commercial systems. Data were collected during gait on 24 patients (12 controls and 12 diabetic neuropathics) with a motion capture system synchronized with two force plates and two baropodometric systems. A four segment three-dimensional foot kinematics model was adopted for the subsegment angles estimation together with a three segment model for the plantar sub-area definition during gait. The neuropathic group exhibited significantly excessive plantar pressure, ground reaction forces on each direction, and a reduced loading surface on the midfoot subsegment (p<0.04). Furthermore the same subsegment displayed excessive dorsiflexion, external rotation, and eversion (p<0.05). Initial results showed that this methodology may enable a more appropriate characterization of patients at risk of foot ulcerations, and help planning prevention programs.

Characterizing multisegment foot kinematics during gait in diabetic foot patients

BackgroundThe prevalence of diabetes mellitus has reached epidemic proportions, this condition may result in multiple and chronic invalidating long term complications. Among these, the diabetic foot, is determined by the simultaneous presence of both peripheral neuropathy and vasculopathy that alter the biomechanics of the foot with the formation of callosity and ulcerations. To diagnose and treat the diabetic foot is crucial to understand the foot complex kinematics. Most of gait analysis protocols represent the entire foot as a rigid body connected to the shank. Nevertheless the existing multisegment models cannot completely decipher the impairments associated with the diabetic foot.MethodsA four segment foot and ankle model for assessing the kinematics of the diabetic foot was developed. Ten normal subjects and 10 diabetics gait patterns were collected and major sources of variability were tested. Repeatability analysis was performed both on a normal and on a diabetic subject. Direct skin marker placement was chosen in correspondence of 13 anatomical landmarks and an optoelectronic system was used to collect the data.ResultsJoint rotation normative bands (mean plus/minus one standard deviation) were generated using the data of the control group. Three representative strides per subject were selected. The repeatability analysis on normal and pathological subjects results have been compared with literature and found comparable. Normal and pathological gait have been compared and showed major statistically significant differences in the forefoot and midfoot dorsi-plantarflexion.ConclusionEven though various biomechanical models have been developed so far to study the properties and behaviour of the foot, the present study focuses on developing a methodology for the functional assessment of the foot-ankle complex and for the definition of a functional model of the diabetic neuropathic foot. It is, of course, important to evaluate the major sources of variation (true variation in the subjects gait and artefacts from the measurement procedure). The repeatability of the protocol was therefore examined, and results showed the suitability of this method both on normal and pathological subjects. Comparison between normal and pathological kinematics analysis confirmed the validity of a similar approach in order to assess neuropathics biomechanics impairment.

Microangiopathy is independently associated with presence, severity and composition of carotid atherosclerosis in type 2 diabetes.

BACKGROUND AND AIMS Common mechanisms for the development of micro- and macroangiopathic diabetic complications have been suggested. We aimed to cross-sectionally investigate strength and characteristics of the association between carotid atherosclerosis and microangiopathy in type 2 diabetic patients. METHODS AND RESULTS Common carotid artery intima-media thickness (cIMT), carotid plaque (CP) type and degree of stenosis were evaluated by ultrasound, along with the determination of anthropometric parameters, HbA1c, lipid profile, assessment of diabetic retinopathy and nephropathy, in 662 consecutive patients with type 2 diabetes mellitus (T2DM). Patients were divided according to high/low cIMT, presence/absence of CP and of retinopathy and nephropathy. Patients with CP were older, more prevalently males, past smokers, had longer diabetes duration, significantly lower HDL cholesterol and more prevalent ischemic heart disease (all p<0.05) as compared to those with cIMT < 1 mm. Microangiopathies were more prevalent in patients with CP than in those without. At multivariate logistic regression, factors independently associated with the presence of CP were age, past smoke, HDL cholesterol, retinopathy and retinopathy plus nephropathy. A significant independent correlation of CP stenosis with stage of retinopathy and nephropathy was found. Finally, echolucent CPs were associated with a lower prevalence of proliferative retinopathy than CP containing calcium deposits. CONCLUSION In T2DM, retinopathy, alone or in combination with nephropathy, is independently associated to CP, and severity of microangiopathy correlates with severity of carotid atherosclerosis. These observations, together with the different prevalence of proliferative retinopathy according to CP types, point to possible common pathogenic mechanisms in micro- and macrovascular complications.

The role of foot morphology on foot function in diabetic subjects with or without neuropathy

The aim of this study was to investigate the role of foot morphology, related with respect to diabetes and peripheral neuropathy in altering foot kinematics and plantar pressure during gait. Healthy and diabetic subjects with or without neuropathy with different foot types were analyzed. Three dimensional multisegment foot kinematics and plantar pressures were assessed on 120 feet: 40 feet (24 cavus, 20 with valgus heel and 11 with hallux valgus) in the control group, 80 feet in the diabetic (25 cavus 13 with valgus heel and 13 with hallux valgus) and the neuropathic groups (28 cavus, 24 with valgus heel and 18 with hallux valgus). Subjects were classified according to their foot morphology allowing further comparisons among the subgroups with the same foot morphology. When comparing neuropathic subjects with cavus foot, valgus heel with controls with the same foot morphology, important differences were noticed: increased dorsiflexion and peak plantar pressure on the forefoot (P<0.05), decreased contact surface on the hindfoot (P<0.03). While results indicated the important role of foot morphology in altering both kinematics and plantar pressure in diabetic subjects, diabetes appeared to further contribute in altering foot biomechanics. Surprisingly, all the diabetic subjects with normal foot arch or with valgus hallux were no more likely to display significant differences in biomechanics parameters than controls. This data could be considered a valuable support for future research on diabetic foot function, and in planning preventive interventions.

3D finite element model of the diabetic neuropathic foot: A gait analysis driven approach

Diabetic foot is an invalidating complication of diabetes that can lead to foot ulcers. Three-dimensional (3D) finite element analysis (FEA) allows characterizing the loads developed in the different anatomical structures of the foot in dynamic conditions. The aim of this study was to develop a subject specific 3D foot FE model (FEM) of a diabetic neuropathic (DNS) and a healthy (HS) subject, whose subject specificity can be found in term of foot geometry and boundary conditions. Kinematics, kinetics and plantar pressure (PP) data were extracted from the gait analysis trials of the two subjects with this purpose. The FEM were developed segmenting bones, cartilage and skin from MRI and drawing a horizontal plate as ground support. Materials properties were adopted from previous literature. FE simulations were run with the kinematics and kinetics data of four different phases of the stance phase of gait (heel strike, loading response, midstance and push off). FEMs were then driven by group gait data of 10 neuropathic and 10 healthy subjects. Model validation focused on agreement between FEM-simulated and experimental PP. The peak values and the total distribution of the pressures were compared for this purpose. Results showed that the models were less robust when driven from group data and underestimated the PP in each foot subarea. In particular in the case of the neuropathic subjects model the mean errors between experimental and simulated data were around the 20% of the peak values. This knowledge is crucial in understanding the aetiology of diabetic foot.

Hypovitaminosis D is associated with lower urinary tract symptoms and benign prostate hyperplasia in type 2 diabetes

Lower urinary tract symptoms (LUTS) may develop more commonly in men with type 2 diabetes mellitus (T2DM). LUTS are often associated with benign prostate hyperplasia (BPH), in general population. An association between LUTS and hypovitaminosis D, and between hypovitaminosis D and type 2 diabetes (T2DM), has also been suggested. Thus, we aim to evaluate possible relationships between hypovitaminosis D, LUTS, and BPH in T2DM men. In this prospective observational study, 67 T2DM males (57.9 ± 9.28 years) underwent medical history collection, International Prostate Symptom Score (IPSS) questionnaire, that allows the identification and grading of LUTS, physical examination, biochemical/hormonal blood tests (fasting plasma glucose, glycated haemoglobin, total cholesterol, high‐density lipoprotein cholesterol, triglycerides, creatinine, LH, total testosterone, estradiol (E2), 25‐OH‐vitamin D, PTH, calcium, phosphate, and PSA) and ultrasound transrectal prostate examination. Subdividing patients into three groups, on the base of 25‐OH‐vitamin D concentration (sufficiency ≥50; insufficiency >25 < 50; and deficiency ≤25 nm), a significant progressive increase of prostate volume (p = 0.037), IPSS score (p = 0.019), diastolic blood pressure (p = 0.018), and a significant decrease in HDL cholesterol (p = 0.038) were observed. 25‐OH‐Vitamin D levels were inversely correlated with both IPSS (R = −0.333; p = 0.006) and prostate volume (R = −0.311; p = 0.011). At multivariate analysis, hypovitaminosis D remained an independent predictor of both IPSS and prostate volume. In conclusion, we showed, for the first time, an association between 25‐OH‐vitamin D deficiency, LUTS, and BPH in T2DM men.

Altered EMG patterns in diabetic neuropathic and not neuropathic patients during step ascending and descending.

Diabetic peripheral neuropathy (DPN) causes motor control alterations during daily life activities. Tripping during walking or stair climbing is the predominant cause of falls in the elderly subjects with DPN and without (NoDPN). Surface Electromyography (sEMG) has been shown to be a valid tool for detecting alterations of motor functions in subjects with DPN. This study aims at investigating the presence of functional alterations in diabetic subjects during stair climbing and at exploring the relationship between altered muscle activation and temporal parameter. Lower limb muscle activities, temporal parameters and speed were evaluated in 50 subjects (10 controls, 20 with DPN, 20 without DPN), while climbing up and down a stair, using sEMG, three-dimentional motion capture and force plates. Magnitude and timing of sEMG linear envelopes peaks were extracted. Level walking was used as reference condition for the comparison with step negotiation. sEMG, speed and temporal parameters revealed significant differences among all groups of patients. Results showed an association between earlier activation of lower limb muscles and reduced speed in subjects with DPN. Speed and temporal parameters significantly correlated with sEMG (p<0.05). The findings of this study are encouraging and could be used to improve rehabilitation programs aiming at reducing falls risk in diabetic subjects.

Identification of diabetic neuropathic patients at risk of foot ulceration through finite element models and cluster analysis

Background Diabetic foot is an invalidating complication of diabetes mellitus that can lead to foot ulceration and amputations. While experimental analyses are limited solely to measurements of interfacial variables, three-dimensional (3D) patient specific finite element models (FEMs) of the foot can provide both the interfacial pressures and insight into internal stresses and strains tolerated by the plantar tissue [1]. FEMs allows quantifying the loads developed in the different anatomical structures of the foot and to understand how these affect foot tissue [2]. The aim of this study was to identify the neuropathic subjects at risk of ulceration with a cluster analysis classification of simulated plantar pressures and internal stresses. Simulations were ran with gait analysis data acquired 5 years prior to ulcerations.

Foot type biomechanics in diabetic and not diabetic subjects

Background The aim of this study was to investigate the role of foot morphology with respect to diabetes and peripheral neuropathy in altering foot kinematics, kinetics and plantar pressure (PP) during gait. Materials and methods Simultaneous 3-dimensional multisegment foot kinematics [1], kinetics and PP [2] of healthy and diabetic subjects with different type of foot were determined. 120 feet were examined (cavus, valgus heel and hallux

Comparison of lower limb muscle strength between diabetic neuropathic and healthy subjects using OpenSim

Diabetes neuropathy and vasculopathy are the two major complications of diabetes mellitus, leading to diabetic foot disease, of which the worst consequences are plantar ulcers and amputations. Motor impairments like joint stiffness and loss of balance are distinctive effects of diabetes and they have been extensively explored. However, while altered muscle function has been also assessed through experimentally measured surface electromyography, little is known about muscle forces. The objective of this study was to estimate muscle forces in subjects with diabetes and to use these data to identify differences with respect to a population of healthy subjects matched for age and BMI. This was obtained by generating musculoskeletal models of 10 diabetic and 10 control subjects in OpenSim starting from experimentally recorded data. Dynamic simulations of motion were run and hence muscle forces calculated. Student T test (p<0.05) was used to compare joints kinematics, kinetics and muscle forces between the two populations. Significant changes were observed between lower limb muscle forces and activation of diabetic and healthy subjects, as well as between joints kinematics and kinetics. In particular muscles related to foot movements proved to be stronger in the healthy population. The typical ankle rigidity of the diabetic population was confirmed by a lower range of motion registered at the ankle plantar/flexion angle associated with weaker dorsal-plantar flexor muscles. The information provided by this methodology can help planning specific training programs aiming at augmenting muscle strength and joints mobility, and they can also improve the evaluation of the potential benefits.