Indentation assessment of plantar foot tissue in diabetic patients

Zheng, YP; Choi, Young-Gwon; Wong, K.P.; Mak, Arthur F.T.

doi:10.1109/iembs.1999.802712

Cited by 4 publications

(3 citation statements)

References 3 publications

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“…This level of correlation is likely to be the result of data analysis after separating by loss of sensation. By comparison, previous reports 11,16 presented low values of negative correlation coefficients between foot sole tissue thickness and foot pressures and in a few plantar areas, and this suggests that the techniques described in this report may be more valuable to studying the pathogenesis of plantar ulcers.…”

Section: Discussionsupporting

confidence: 49%

The Role of Skin Hardness, Thickness, and Sensory Loss on Standing Foot Power in the Development of Plantar Ulcers in Patients with Diabetes Mellitus—A Preliminary Study

Thomas

Patil

Radhakrishnan

et al. 2003

The International Journal of Lower Extremity Wounds

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This article presents the results of a study on patients with diabetic neuropathy to find the relationships between the foot pressures characterized by power ratio (PR), foot sole hardness (Shore values), and foot sole soft tissue thickness. The results showed that the increase in PR values for diabetic patients in the upper sensation loss levels (S = 7.5 to 10 g) compared to the corresponding increase in lower sensation loss (S=3 to 4.5 g)were of the order of 5 times in the lateral heel and big toe, respectively, and 4 times in the first metatarsal head regions. The increase in PR values for diabetic patients in the upper Shore value regions (30 to 40) compared to the corresponding increase in lower Shore value regions (20 to 30) were of the order of 3.4 times in lateral heel and 2.4, 2.0, and 2.3 times in the first, second, and lateral metatarsal head regions, respectively. At sites contiguous to frank ulcers for foot sole hardness (Shore values of 50) at sensation level > 10 g PR was as high as 59, and foot sole thickness values were also greater than the corresponding normal values. The study shows all measured parameters may play a part in the development of plantar ulcers.

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Section: Discussionsupporting

confidence: 49%

The Role of Skin Hardness, Thickness, and Sensory Loss on Standing Foot Power in the Development of Plantar Ulcers in Patients with Diabetes Mellitus—A Preliminary Study

Thomas

Patil

Radhakrishnan

et al. 2003

The International Journal of Lower Extremity Wounds

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“…The elastic moduli of the PAAM substrates in this study were chosen carefully to match the values reported for various tissues and organs in vivo. For example, the Young’s modulus for skin has been shown to vary between 14 kPa and 60 kPa based upon the underlying muscular contractions . The elastic modulus of cartilage has been observed to be in the 20 kPa to 30 kPa range and the values for the elastic modulus of the liver ranges between 20 and 60 kPa , .…”

Section: Discussionmentioning

confidence: 99%

Cell Migration at the Interface of a Dual Chemical-Mechanical Gradient

Yang

Rajagopalan

2010

ACS Appl. Mater. Interfaces

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Cell migration plays a critical role in numerous physiological processes, such as wound healing, response to inflammation, and cancer metastasis. In recent years, accumulating evidence indicates that cell movement is regulated not only by chemical signals but also by mechanical stimuli. In this study, the primary goal is to identify whether a chemical or mechanical stimulus plays the decisive role in directing cell migration. Measuring the motility of cells when they are presented with a combination of chemical and mechanical cues will provide insight into the complex physiological phenomena that guide and direct migration. A novel polyacrylamide hydrogel was designed with an interfacial region where the chemical and mechanical properties varied in opposing directions. One side of the interface was stiff (high Young's modulus) with a low protein concentration, whereas the other side of the interface was compliant (low Young's modulus) with a high protein concentration. The chemical gradient was created by varying the collagen (type I) concentration and the mechanical gradient was introduced by changing the extent of cross-linking in the polymer. The length of the interface with opposing chemical-mechanical profiles was found to be approximately 100 mum. Our results demonstrate that when Balb/c 3T3 fibroblasts were presented with a choice, they either migrated preferentially toward the high-collagen-compliant (low Young's modulus) side of the interfacial region or remained on the high-collagen region, suggesting a more dominant role for chemical stimuli in directing fibroblast locomotion.

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“…The hardness of plantar skin in diabetic neuropathic feet is higher than in control subjects (PIAGGESSI et al, 1999). it is reported that foot sole soft-tissue thicknesses of diabetic subjects are also less than those of control subjects (ZHENG et al, 1999). The foot models available in the literature (JACOB and PATIL, 1999;WENG-PIN et al, 2001) have considered isotropic properties for foot sole soft tissue.…”

Section: Introductionmentioning

confidence: 97%

Three-dimensional stress analysis for the mechanics of plantar ulcers in diabetic neuropathy

Thomas

Patil

Radhakrishnan

2004

Med. Biol. Eng. Comput.

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In diabetic neuropathic subjects, the hardness of foot sole soft tissue increases, and its thickness reduces, in different foot sole areas. Finite element analysis (FEA) of a three-dimensional two-arch model of the foot was performed to evaluate the effect of foot sole stresses on plantar ulcer development. Three sets of foot sole soft-tissue properties, i.e. isotropic (with control hardness value), diabetic isotropic (with higher hardness value) and anisotropic diabetic conditions, were simulated in the push-off phase, with decreasing foot sole soft-tissue thicknesses in the forefoot region, and the corresponding stresses were calculated. The results of the stress analyses for diabetic subject (anisotropic) foot models showed that, with non-uniformly increased hardness and decreased foot sole soft-tissue thickness, the normal and shear stresses at the foot sole increased (compared with control values) by 52.6% and 53.4%, respectively. Stress analyses also showed high ratios of gradients of normal and shear stresses of the order of 6.6 and 3.3 times the control values on the surface of the foot sole, and high relative values of stress gradients for normal and shear stresses of 6.25 and 4.35 times control values, respectively, between the foot sole surface and the adjacent inner layer of the foot sole, around a particular region of the foot sole with anisotropic properties. These ratios of high gradients and relative gradients of stresses due to changes in soft-tissue properties may be responsible for the development of plantar ulcers in diabetic neuropathic feet.

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Indentation assessment of plantar foot tissue in diabetic patients

Cited by 4 publications

References 3 publications

The Role of Skin Hardness, Thickness, and Sensory Loss on Standing Foot Power in the Development of Plantar Ulcers in Patients with Diabetes Mellitus—A Preliminary Study

The Role of Skin Hardness, Thickness, and Sensory Loss on Standing Foot Power in the Development of Plantar Ulcers in Patients with Diabetes Mellitus—A Preliminary Study

Cell Migration at the Interface of a Dual Chemical-Mechanical Gradient

Three-dimensional stress analysis for the mechanics of plantar ulcers in diabetic neuropathy

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