Roentgenographic Measurement of Skin and Heel-Pad Thickness in the Diagnosis of Acromegaly

Fields, Murray L.; Greenberg, Benjamin H.; Burkett, Luther L.

doi:10.1097/00000441-196710000-00017

Cited by 15 publications

(4 citation statements)

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“…A single-acting, master/slave hydraulic loading device produced triangle or sine shaped displacement curves of 10 mm maximum amplitude at theoretical loading rates up to 6 Hz and a maximum load of 1500 N. These parameters exceed the largest displacement necessary to approximate strain under body weight loading of the maximum plantar fat pad thickness expected. 12–18 They also simulate the frequency content of gait 19 and allow for 1.2 × body weight forces for most people.…”

Section: Methodsmentioning

confidence: 99%

“…A literature review found that unloaded adult plantar soft tissue under the metatarsals and calcaneus is generally between 5.4 and 26.5 mm thick, and that the maximum strain in the soft tissue beneath either location under body weight is approximately 0.45. [12][13][14][15][16][17][18] For each test, the actual displacement of the loading platen versus the prescribed displacement was analyzed at maximum extension for each cycle. Data from the first 10 cycles were excluded from that analysis due to preconditioning of the silicone gel.…”

Section: Verification Testingmentioning

confidence: 99%

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The design and validation of a magnetic resonance imaging–compatible device for obtaining mechanical properties of plantar soft tissue via gated acquisition

Williams

Stebbins

Cavanagh

et al. 2015

Proc Inst Mech Eng H

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Changes in the mechanical properties of the plantar soft tissue in people with diabetes may contribute to the formation of plantar ulcers. Such ulcers have been shown to be in the causal pathway for lower extremity amputation. The hydraulic plantar soft tissue reducer (HyPSTER) was designed to measure in vivo, rate-dependent plantar soft tissue compressive force and three-dimensional deformations to help understand, predict, and prevent ulcer formation. These patient-specific values can then be used in an inverse finite element analysis to determine tissue moduli, and subsequently used in a foot model to show regions of high stress under a wide variety of loading conditions. The HyPSTER uses an actuator to drive a magnetic resonance imaging-compatible hydraulic loading platform. Pressure and actuator position were synchronized with gated magnetic resonance imaging acquisition. Achievable loading rates were slower than those found in normal walking because of a water-hammer effect (pressure wave ringing) in the hydraulic system when the actuator direction was changed rapidly. The subsequent verification tests were, therefore, performed at 0.2 Hz. The unloaded displacement accuracy of the system was within 0.31%. Compliance, presumably in the system's plastic components, caused a displacement loss of 5.7 mm during a 20-mm actuator test at 1354 N. This was accounted for with a target to actual calibration curve. The positional accuracy of the HyPSTER during loaded displacement verification tests from 3 to 9 mm against a silicone backstop was 95.9% with a precision of 98.7%. The HyPSTER generated minimal artifact in the magnetic resonance imaging scanner. Careful analysis of the synchronization of the HyPSTER and the magnetic resonance imaging scanner was performed. With some limitations, the HyPSTER provided key functionality in measuring dynamic, patient-specific plantar soft tissue mechanical properties.

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Section: Methodsmentioning

confidence: 99%

Section: Verification Testingmentioning

confidence: 99%

The design and validation of a magnetic resonance imaging–compatible device for obtaining mechanical properties of plantar soft tissue via gated acquisition

Williams

Stebbins

Cavanagh

et al. 2015

Proc Inst Mech Eng H

View full text Add to dashboard Cite

show abstract

“…Locations such as the finger, elbow and the wrist which have a significant curvature were modelled as curved spherical surfaces, and the rest of the sections were modelled as flat cylindrical stacks of skin layers and bone, as shown in Figure 5.20. The thickness of the different skin layers were chosen based on the extensive human skin thickness data available in literature [180][181][182][183][184][185][186][187][188][189][190][191][192][193]. The approximate dimensions of the skin and bone section geometries used in our work are presented in Figure 5.20, and the thickness values adopted for different skin and bone section layers are listed in Table 5.3.…”

Section: Geometrical Modelingmentioning

confidence: 99%

Biofidelic soft composites–experimental and computational modeling

Chanda¹

2018

Preprint

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Biofidelic soft composites or tissues form the building blocks of the human body. Understanding the complex mechanics of these soft composites is the key to understanding the genesis and progression of disease. Biomechanically, soft composites exhibit anisotropic mechanical behavior and comprise of multiple fiber layers within a soft matrix. To date, there is a lack of understanding of the anisotropic mechanical behavior of soft composites, primarily due to unavailability of a robust characterization framework. In this dissertation, novel multiscale computational and experimental investigation models are developed to simulate and characterize anisotropic soft composite mechanical behavior. Soft composite surrogates were first developed to simulate various tissues in the human body namely the skin, brain, artery and vaginal tissues. Novel anisotropic soft composite models were also fabricated taking into consideration the tissue anisotropy and multifunctional properties. Hyperelastic anisotropic constitutive relationships were formulated to precisely characterize the mechanical behavior of soft composite considering varying fiber and matrix contributions, fiber-matrix interactions, fiber orientations and multiple fiber layers. Coupled with high fidelity experimental and computational models, microscopy, and Digital Image Correlation (DIC) studies, the damage and repair of soft composite surrogates are also discussed in this dissertation, with relevance to soft tissue wounds and suture. Computational modeling to understand the interaction between multiple soft composite systems and its effect on soft composite damage are also highlighted in this work. Some specific soft composite interaction systems modeled were the female pelvic system under abdominal loads, whole body impact due to blast, and ulceration in diabetic foot. This dissertation lays the foundation for micro and macro scale anisotropic soft composite modeling and characterization using high fidelity experimental and numerical techniques which will be indispensable for studying tissue mechanics and other soft composite applications in engineering and medicine.

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“…6,7 For example, the heel pad is grossly hypertrophied in acromegaly, as measured by x-rays. 5 Amyloid deposition has been described in the body fat of rheumatoid arthritis patients. 1…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Heel Pad Fat in Rheumatoid Arthritis

et al. 1999

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The heel fat pad is organized, both in structure and in composition, to bear the stresses and strains of normal activities and to permit pain-free weightbearing. The fatty acid composition of heel pads in 11 patients with rheumatoid arthritis, a disease process frequently associated with heel fat pad atrophy, was analyzed using gas-liquid chromatography and was compared with that of patients without systemic disease. The heels of patients with rheumatoid arthritis demonstrated a significant change in the composition of saturated fatty acids when compared with heels of nonrheumatoid patients. This composition reflects an increased fat viscosity, which decreases the ability of the heel to absorb and dissipate the energy generated during ambulation. This factor could cause degeneration of the heel septal system, with resulting fat pad atrophy.

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Roentgenographic Measurement of Skin and Heel-Pad Thickness in the Diagnosis of Acromegaly

Cited by 15 publications

References 0 publications

The design and validation of a magnetic resonance imaging–compatible device for obtaining mechanical properties of plantar soft tissue via gated acquisition

The design and validation of a magnetic resonance imaging–compatible device for obtaining mechanical properties of plantar soft tissue via gated acquisition

Biofidelic soft composites–experimental and computational modeling

Analysis of the Heel Pad Fat in Rheumatoid Arthritis

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