Subject-specific material properties of the heel pad: An inverse finite element analysis.

Individuals with diabetes are at a higher risk of developing foot ulcers. To better understand internal soft tissue loading and potential treatment options, subject-specific finite element (FE) foot models have been used. However, existing models typically lack subject-specific soft tissue material properties and only utilize subject-specific anatomy.

Virtually optimized insoles for offloading the diabetic foot: A randomized crossover study.

Unlabelled: Integration of objective biomechanical measures of foot function into the design process for insoles has been shown to provide enhanced plantar tissue protection for individuals at-risk of plantar ulceration. The use of virtual simulations utilizing numerical modeling techniques offers a potential approach to further optimize these devices. In a patient population at-risk of foot ulceration, we aimed to compare the pressure offloading performance of insoles that were optimized via numerical simulation techniques against shape-based devices.

A preliminary study of patient-specific mechanical properties of diabetic and healthy plantar soft tissue from gated magnetic resonance imaging.

Foot loading rate, load magnitude, and the presence of diseases such as diabetes can all affect the mechanical properties of the plantar soft tissues of the human foot. The hydraulic plantar soft tissue reducer instrument was designed to gain insight into which variables are the most significant in determining these properties. It was used with gated magnetic resonance imaging to capture three-dimensional images of feet under dynamic loading conditions.

Towards human exploration of space: the THESEUS review series on muscle and bone research priorities.

Without effective countermeasures, the musculoskeletal system is altered by the microgravity environment of long-duration spaceflight, resulting in atrophy of bone and muscle tissue, as well as in deficits in the function of cartilage, tendons, and vertebral disks. While inflight countermeasures implemented on the International Space Station have evidenced reduction of bone and muscle loss on low-Earth orbit missions of several months in length, important knowledge gaps must be addressed in order to develop effective strategies for managing human musculoskeletal health on exploration class missions well beyond Earth orbit. Analog environments, such as bed rest and/or isolation environments, may be employed in conjunction with large sample sizes to understand sex differences in countermeasure effectiveness, as well as interaction of exercise with pharmacologic, nutritional, immune system, sleep and psychological countermeasures.

Replacement of daily load attenuates but does not prevent changes to the musculoskeletal system during bed rest.

The dose-response effects of exercise in reduced gravity on musculoskeletal health have not been well documented. It is not known whether or not individualized exercise prescriptions can be effective in preventing the substantial loss in bone mineral density and muscle function that have been observed in space flight and in bed rest. In this study, typical daily loads to the lower extremities were quantified in free-living subjects who were then randomly assigned to control or exercise groups.

Simplified versus geometrically accurate models of forefoot anatomy to predict plantar pressures: A finite element study.

Integration of patient-specific biomechanical measurements into the design of therapeutic footwear has been shown to improve clinical outcomes in patients with diabetic foot disease. The addition of numerical simulations intended to optimise intervention design may help to build on these advances, however at present the time and labour required to generate and run personalised models of foot anatomy restrict their routine clinical utility. In this study we developed second-generation personalised simple finite element (FE) models of the forefoot with varying geometric fidelities.

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

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.

Footwear and offloading interventions to prevent and heal foot ulcers and reduce plantar pressure in patients with diabetes: a systematic review.

Background: Footwear and offloading techniques are commonly used in clinical practice for preventing and healing of foot ulcers in persons with diabetes. The goal of this systematic review is to assess the medical scientific literature on this topic to better inform clinical practice about effective treatment.

Methods: We searched the medical scientific literature indexed in PubMed, EMBASE, CINAHL, and the Cochrane database for original research studies published since 1 May 2006 related to four groups of interventions: (1) casting; (2) footwear; (3) surgical offloading; and (4) other offloading interventions.

A novel computational method for evaluating osteochondral autografts in distal radius reconstruction.

Background: We describe a novel computational method for assessing the fit of an osteochondral graft. We applied our software to five normal wrist computed tomography (CT) scans to determine the fit of the scaphoid to the lunate fossa of the distal radius.

Methods: CT scans of five wrists were digitally rendered.

The biomechanical function of the anterolateral ligament of the knee.

Background: Recent anatomic investigations of the lateral structures of the knee have identified a new ligament, called the anterolateral ligament (ALL). To date, the anterolateral ligament has not been biomechanically tested to determine its function.

Hypothesis: The ALL of the knee will resist internal rotation at high angles of flexion but will not resist anterior drawer forces.

What has finite element analysis taught us about diabetic foot disease and its management? A systematic review.

Background: Over the past two decades finite element (FE) analysis has become a popular tool for researchers seeking to simulate the biomechanics of the healthy and diabetic foot. The primary aims of these simulations have been to improve our understanding of the foot's complicated mechanical loading in health and disease and to inform interventions designed to prevent plantar ulceration, a major complication of diabetes. This article provides a systematic review and summary of the findings from FE analysis-based computational simulations of the diabetic foot.

Simple finite element models for use in the design of therapeutic footwear.

Therapeutic footwear is frequently prescribed in cases of rheumatoid arthritis and diabetes to relieve or redistribute high plantar pressures in the region of the metatarsal heads. Few guidelines exist as to how these interventions should be designed and what effect such interventions actually have on the plantar pressure distribution. Finite element analysis has the potential to assist in the design process by refining a given intervention or identifying an optimal intervention without having to actually build and test each condition.

Prevention of recurrent foot ulcers with plantar pressure-based in-shoe orthoses: the CareFUL prevention multicenter randomized controlled trial.

Objective: To assess the efficacy of in-shoe orthoses that were designed based on shape and barefoot plantar pressure in reducing the incidence of submetatarsal head plantar ulcers in people with diabetes, peripheral neuropathy, and a history of similar prior ulceration.

Research Design And Methods: Single-blinded multicenter randomized controlled trial with subjects randomized to wear shape- and pressure-based orthoses (experimental, n = 66) or standard-of-care A5513 orthoses (control, n = 64). Patients were followed for 15 months, until a study end point (forefoot plantar ulcer or nonulcerative plantar forefoot lesion) or to study termination.

A novel lunar bed rest analogue.

Introduction: Humans will eventually return to the Moon and thus there is a need for a ground-based analogue to enable the study of physiological adaptations to lunar gravity. An important unanswered question is whether or not living on the lunar surface will provide adequate loading of the musculoskeletal system to prevent or attenuate the bone loss that is seen in microgravity. Previous simulations have involved tilting subjects to an approximately 9.

Optimising muscle parameters in musculoskeletal models using Monte Carlo simulation.

The use of musculoskeletal simulation software has become a useful tool for modelling joint and muscle forces during human activity, including in reduced gravity because direct experimentation is difficult. Knowledge of muscle and joint loads can better inform the design of exercise protocols and exercise countermeasure equipment. In this study, the LifeModeler™ (San Clemente, CA, USA) biomechanics simulation software was used to model a squat exercise.

Optimization of nonlinear hyperelastic coefficients for foot tissues using a magnetic resonance imaging deformation experiment.

Accurate prediction of plantar shear stress and internal stress in the soft tissue layers of the foot using finite element models would provide valuable insight into the mechanical etiology of neuropathic foot ulcers. Accurate prediction of the internal stress distribution using finite element models requires that realistic descriptions of the material properties of the soft tissues are incorporated into the model. Our investigation focused on the creation of a novel three-dimensional (3D) finite element model of the forefoot with multiple soft tissue layers (skin, fat pad, and muscle) and the development of an inverse finite element procedure that would allow for the optimization of the nonlinear elastic coefficients used to define the material properties of the skin muscle and fat pad tissue layers of the forefoot based on a Ogden hyperelastic constitutive model.

Design of an implant for first metatarsophalangeal hemi-arthroplasty.

This study was designed to examine the three-dimensional geometry of the head of the first metatarsal bone of the foot. Ninety-seven adult first metatarsal head (MTH1) bones were scanned using a laser scanner at 400 dpi. A best-fit ellipsoid was obtained from the articular surfaces of MTH1 for each size group using nonlinear unconstrained optimisation.

Clustering and classification of regional peak plantar pressures of diabetic feet.

High plantar pressures have been associated with foot ulceration in people with diabetes, who can experience loss of protective sensation due to peripheral neuropathy. Therefore, characterization of elevated plantar pressure distributions can provide a means of identifying diabetic patients at potential risk of foot ulceration. Plantar pressure distribution classification can also be used to determine suitable preventive interventions, such as the provision of an appropriately designed insole.

Comparison of hexahedral and tetrahedral elements in finite element analysis of the foot and footwear.

Finite element analysis has been widely used in the field of foot and footwear biomechanics to determine plantar pressures as well as stresses and strains within soft tissue and footwear materials. When dealing with anatomical structures such as the foot, hexahedral mesh generation accounts for most of the model development time due to geometric complexities imposed by branching and embedded structures. Tetrahedral meshing, which can be more easily automated, has been the approach of choice to date in foot and footwear biomechanics.

Miniaturized sensors to monitor simulated lunar locomotion.

Introduction: Human activity monitoring is a useful tool in medical monitoring, military applications, athletic coaching, and home healthcare. We propose the use of an accelerometer-based system to track crewmember activity during space missions in reduced gravity environments. It is unclear how the partial gravity environment of the Moorn or Mars will affect human locomotion.

Off-loading the diabetic foot for ulcer prevention and healing.

Retrospective and prospective studies have shown that elevated plantar pressure is a causative factor in the development of many plantar ulcers in diabetic patients and that ulceration is often a precursor of lower-extremity amputation. Herein, we review the evidence that relieving areas of elevated plantar pressure (off-loading) can prevent and heal plantar ulceration.There is no consensus in the literature concerning the role of off-loading through footwear in the primary or secondary prevention of ulcers.

Off-loading the diabetic foot for ulcer prevention and healing.

Retrospective and prospective studies have shown that elevated plantar pressure is a causative factor in the development of many plantar ulcers in diabetic patients and that ulceration is often a precursor of lower-extremity amputation. Herein, we review the evidence that relieving areas of elevated plantar pressure (off-loading) can prevent and heal plantar ulceration. There is no consensus in the literature concerning the role of off-loading through footwear in the primary or secondary prevention of ulcers.