Peter Cavanagh

• University of Washington

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 e...

Background: Treadmills have been employed as both a form of exercise and a countermeasure to prevent changes in the musculoskeletal system on almost all NASA missions and many Russian missions since the early Space Shuttle flights. It is possible that treadmills may also be part of exercise programs on future Mars missions and that they may be a c...

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 pa...

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 gat...

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,...

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...

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 com...

Footwear science has made rapid progress in the last decade and this has led to safer and more efficient footwear for sports and expedition activities. While such topics as energy storage and return have been studied in the athletic footwear area, there is no indication that these concepts have been explored for military footwear, other than in the...

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. The ALL of the knee will resist internal rotation at high angles of flexion but will not resist anterior draw...

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 interventio...

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 eleme...

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. CT scans of five wrists were digitally rendered. The capitate facet of the scaphoid was fit to the lunate...

Understanding the skeletal effects of resistance exercise involves delineating the spatially heterogeneous response of bone to load distributions from different muscle contractions. Bone mineral density (BMD) analyses may obscure these patterns by averaging data from tissues with variable mechano-response. To assess the proximal femoral response to...

OBJECTIVE To assess the efficacy of in-shoe orthoses 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 su...

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 see...

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, th...

IntroductionLocomotor and some resistance exercises in space require a gravity replacement force in order to allow 1g-like ground reaction forces to be generated. Currently bungee cords, or other loading devices, interface with the crew member through a harness with a waist belt and shoulder straps. Crew members often find the application of the re...

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 mate...

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 optimisat...

PURPOSE To demonstrate MR imaging changes in cortical, trabecular bone and bone marrow changes in patients after 12 weeks of absolute bedrest simulating microgravity. METHOD AND MATERIALS Eleven healthy volunteer subjects (6 males and 5 females) underwent MRI examinations of lower extermities before and following 12 weeks of absolute bedrest simul...

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 dis...

Most estimates in the literature for the economic cost of treating a diabetic foot ulcer (DFU) are from industrialized countries. There is also marked heterogeneity between the complexity of cases considered in the different studies. The goal of the present article was to estimate treatment costs and costs to patients in five different countries (C...

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 co...

Prolonged weightlessness is associated with declines in musculoskeletal, cardiovascular, and sensorimotor health. Consequently, in-flight countermeasures are required to preserve astronaut health. We developed and tested a novel exercise countermeasure device (CCD) for use in spaceflight with the aim of preserving musculoskeletal and cardiovascular...

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 hu...

As a field, biomechanics comprises research from the molecular and cellular levels, to tissues, to organs, to organisms and their movements. In the past 50 years, the impact of biomechanics research on society has been amplified dramatically. Here, we provide five brief summaries of exemplar biomechanics results that have had substantial impact on...

PURPOSE Prolonged bedrest is a frequently used analog to study musculoskeletal changes that occur during long-duration space flight. This study was conducted to determine changes in the lumbar disc volumes before and after 12 weeks of absolute bed rest in control and exercise groups. METHOD AND MATERIALS 9 subjects, who were not habitual exerciser...

Long-duration exposure to microgravity has been shown to have detrimental effects on the human musculoskeletal system. To date, exercise countermeasures have been the primary approach to maintain bone and muscle mass and they have not been successful. Up until 2008, the three exercise countermeasure devices available on the International Space Stat...

This study examined the relationship between symptoms of depression and the development of diabetic foot ulcers. Participants were 333 patients (71% male; mean age 62 years; 73% with type 2 diabetes) with diabetic peripheral neuropathy (DPN), but without peripheral vascular disease (PVD). Severity of DPN and the presence of PVD were assessed by cli...

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 he...

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. In this article, we review the evidence that relieving areas of elevated plantar pressure (off-loading) can preve...

Characterization of the contact pressure patterns under the foot provides significant insight into pathological conditions such as diabetic peripheral neuropathy [1]. The finite element method (FEM) is widely used in foot biomechanics for predictive simulations of plantar pressures in barefoot and shod conditions [2–6]. In the analysis of the foot,...

Decreased bone mineral density (BMD) in astronauts returning from long-duration spaceflight missions has been well documented, but the altered mechanical loading environment experienced by the musculoskeletal system, which may contribute to these changes, has not been well characterized. The current study describes the loading environment of the lo...

Decrements in muscular strength during long-duration missions in space could be mission-critical during construction and exploration activities. The purpose of this study was to quantify changes in muscle volume, strength, and endurance of crewmembers on the International Space Station (ISS) in the context of new measurements of loading during exer...

Introduction: It has been hypothesized that bone loss arising from long-duration space travel is caused by a reduction in mechanical stimuli to the skeleton. The daily load stimulus (DLS) theory was first proposed to relate daily time histories of mechanical loading from ground reaction forces to bone homeostasis. In this methods paper, an enhance...

The recurrence of foot ulcers is a significant problem in people with diabetic neuropathy. The purpose of this study was to measure in-shoe plantar pressures and other characteristics in a group of neuropathic patients with diabetes who had prior foot ulcers which had remained healed. This was an epidemiological cohort study of patients from diabet...

Loss in bone mineral density and muscle strength in astronauts following long-duration spaceflight have been well documented, but the altered force and movement environments in microgravity which may contribute to these changes have not been well characterized. This paper describes the instrumentation, software, and data collection procedures devel...

The International Foot and Ankle Biomechanics Community (i-FAB) is an international collaborative activity which will have an important impact on the foot and ankle biomechanics community. It was launched on July 2nd 2007 at the foot and ankle session of the International Society of Biomechanics (ISB) meeting in Taipei, Taiwan. i-FAB is driven by t...

The aim of the study was to determine whether diabetic peripheral neuropathy (DPN) is a risk factor for depressive symptoms and examine the potential mechanisms for this relationship. This longitudinal study (9 and 18 month follow-up) of 338 DPN patients (mean age 61 years; 71% male; 73% type 2 diabetes) examined the temporal relationships between...

Management of diabetic foot ulcers presents a major clinical challenge. The response to treatment is often poor and the outcome disappointing, while the costs are high for both healthcare providers and the patient. In such circumstances, it is essential that management should be based on firm evidence and follow consensus. In the case of the diabet...

This review will highlight evidence from crew members flown on space missions >90days to suggest that the adaptations of the skeletal system to mechanical unloading may predispose crew members to an accelerated onset of osteoporosis after return to Earth. By definition, osteoporosis is a skeletal disorder—characterized by low bone mineral density (...

Footwear and offloading techniques are commonly used in clinical practice for the prevention and treatment of foot ulcers in diabetes, but the evidence base to support this use is not well known. The goal of this review was to systematically assess the literature and to determine the available evidence on the use of footwear and offloading interven...

Bus, S A

The purpose of this study was to determine whether custom insoles tailored to contours of the barefoot pressure distribution and shape of a patient's foot can reduce plantar pressures in the metatarsal head (MTH) region to a greater extent than conventional custom insoles. Seventy regions of elevated barefoot pressures (mean peak 834 kPa under MTHs...

It is well known that mechanical forces acting within the soft tissues of the foot can contribute to the formation of neuropathic ulcers in people with diabetes. Presently, only surface measurements of plantar pressure are used clinically to estimate risk status due to mechanical loading. It is currently not known how surface measurements relate to...

PURPOSE To determine changes in the total lipid/creatine of vastus lateralis muscle before and after 12 weeks of absolute bed rest. METHOD AND MATERIALS 6 volunteers, 3 women and 3 men with ages ranging from 23 to 35(average 28 years) years were on absolute bed rest in six degrees tilt head down position for 12 weeks to simulate conditions of a sp...

Fixation of tendon transfers with a bioabsorbable interference-fit screw has several advantages over other fixation methods: decreased dissection, operative time, and blood loss; preservation of tendon length; no interference with radiographic studies; no need for implant removal; and no barrier to revision surgery. Whether strength of fixation is...

Disorders of the first ray of the foot (defined as the hard and soft tissues of the first metatarsal, the sesamoids, and the phalanges of the great toe) are common, and therapeutic interventions to address these problems range from alterations in footwear to orthopedic surgery. Experimental verification of these procedures is often lacking, and thu...

Bone and muscle are both compromised during long-term space flight. Experiments are, therefore, in progress using surface electromyography (EMG) and joint angle measurements to compare muscle action on earth and in space over complete working days. To date, there is little information on the reliability of such long-term EMG measurements available...

Older adults have less confidence in their ability to reach upward compared to reaching forward. The forward reach test may, therefore, not be ideally suited for detecting functional deficits that directly affect daily activities. A new test of upward reach and forward reach (along a 50-degree track) were administered to young and older adults. Rea...

This study represents the first step toward testing the hypothesis that hypergravity can be used as a unique resistance training modality for maintaining the health and function of skeletal muscle in microgravity. The primary objectives of this study were to use a human-powered short-arm centrifuge for the following: 1) to determine whether subject...

The enhanced Zero-gravity Locomotion Simulator (eZLS) at NASA Glenn Research Center is described and summary data from a pilot research study comparing comfort and pressure data from two different International Space Station crew exercise harness designs are presented. This new ground-based simulation capability was developed to help address the de...

Using the common-sense model of illness behavior, we developed and validated a self-report instrument for assessment of patients' cognitive and emotional representations of diabetic peripheral neuropathy (DPN) influencing foot self-care. The Patient Interpretation of Neuropathy (PIN) questionnaire, generated from discussions with clinicians and int...

We have outlined an approach to the nonsurgical treatment of diabetic foot ulcers based on an understanding of their etiology. We have emphasized the importance of off-loading as the crucial element to success in healing foot ulcers and preventing their recurrence in those with diabetes. Computerized design of custom insoles can allow the unloading...

During treadmill exercise on the International Space Station (ISS), a restoring load from a subject load device (SLD) is applied through a shoulder-and-waist harness to pull the exercising crewmember toward the treadmill surface. The capacity of this arrangement to provide 1-g-like reaction forces may be critical for effective use of the treadmill...

IntroductionStress and Stress ConcentrationNeuropathy and High Pressure – The Key CombinationMechanisms for Elevated PressurePrimary Prevention: The 30-Second Foot ExaminationPrimary Prevention: The 2-Minute Foot ExaminationBiomechanical Issues in Treating a Plantar UlcerPrimary and Secondary Prevention – The Importance of FootwearSummaryReferences

Since the publication of the third edition of The Foot in Diabetes, there have been important developments in the field of diabetic foot care and its scientific basis, including: The introduction of new technologies such as vacuum therapy, new casting techniques, the use of hormones and growth factors in wound healing; Advances in the understanding...

Finite element (FE) analysis has shown promise for the evaluation of elastomeric foam personal protection devices. Although appropriate representation of foam materials is necessary in order to obtain realistic simulation results, material definitions used in the literature vary widely and often fail to account for the multi-mode loading experience...

harcot neuroarthropathy, or, as it is also known, neuropathic joint dis- ease (NJD), is a particularly severe form of osteoarthritis. It is recognized by severe joint damage in the context of rel- atively little pain in the presence of neu- ropathy and associated with characteristic radiographic changes in well-established disease. Patients with di...

Spaceflight has been shown to cause atrophy, reduced functional capacity, and increased fatigue in lower-limb skeletal muscles. The mechanisms of these losses are not fully understood but are thought to result, in part, from alteration in muscle usage. Knee-joint angles and lower-extremity muscle activity were measured continually, via elecrogoniom...

Plantar heel pain is a common condition that is often exacerbated by the repetitive stresses of walking. Treatment usually includes an in-shoe intervention designed to reduce plantar pressure under the heel by using insoles and a variety of off-the-shelf products. The design process for these products is often intuitive in nature and does not alway...

A numerical-experimental approach has been developed to characterize heel-pad deformation at the material level. Left and right heels of 20 diabetic subjects and 20 nondiabetic subjects matched for age, gender and body mass index were indented using force-controlled ultrasound. Initial tissue thickness and deformation were measured using M-mode ult...

The pathogenesis of the acute Charcot foot of diabetes remains unclear. All patients with this condition have evidence of peripheral neuropathy, with loss of protective sensation and abnormal foot biomechanics. However, the acute Charcot foot is also characterised by a pronounced inflammatory reaction and the pathogenic significance of this inflamm...

People with diabetes develop foot ulcers because of neuropathy (sensory, motor, and autonomic deficits), ischaemia, or both. The initiating injury may be from acute mechanical or thermal trauma or from repetitively or continuously applied mechanical stress. Patients with clinically significant limb ischaemia should be assessed by a vascular surgeon...

We examined the association between severity of diabetic peripheral neuropathy and depressive symptoms and investigated the potential mediators of this association. The Hospital Anxiety and Depression Scale (HADS) was used to assess depressive symptoms in 494 patients (mean age 62 years; 70% male; 72% type 2 diabetic) with diabetic neuropathy diagn...

A major goal of therapeutic footwear in patients with pain or those at risk for skin injury is to relieve focal loading under prominent metatarsal heads. One frequent approach is to place plugs of compliant material into the midsole of the shoe. This study investigated 36 plug designs, a combination of three materials, six geometries, and two place...

Stair design and environmental conditions may play a role in slip accidents on stairs in the workplace, but little is known about the slip resistance requirements on stairs compared to level walking. Older adults have an increased risk of falling compared to younger adults and may be at greater risk during stair negotiation. The purpose of this stu...

Bone loss in the lower extremities and lumbar spine is an established consequence of long-duration human space flight. Astronauts typically lose as much bone mass in the proximal femur in 1 month as postmenopausal women on Earth lose in 1 year. Pharmacological interventions have not been routinely used in space, and countermeasure programs have dep...

lthough the benefits of total contact casting for healing plantar neuro- pathic ulcers are consistent throughout a large body of available liter- ature, the method of cast application var- ies (1-17). Cast structure at the ulcer site provides one major variance, i.e., should thecastcreatetotalcontactwiththeentire plantar surface of the foot or shou...

It is likely that many stair accidents result from a trip during stair negotiation, yet few studies have examined the exact nature of balance loss during falls on stairs. The purpose of this study was to investigate potential age-related differences in the minimum clearance of the foot during stair descent, and to explore whether the minimum foot c...

The aim of this study was to quantify the association between claw/hammer toe deformity and changes in submetatarsal head (sub-MTH) fat-pad geometry in diabetic neuropathic feet. Thirteen neuropathic diabetic subjects (mean age 56.2 years) with toe deformity, 13 age- and sex-matched neuropathic diabetic control subjects without deformity, and 13 ag...

Diabetes is the leading cause of nontraumatic lower-extremity amputations in the United States. Most amputations are preceded by an ulcer, and ulcers are costly in their own right. Most ulcers are neuropathic in etiology and plantar in location. They occur typically at sites of high mechanical loading because of repetitive trauma in people with los...

To study the effects of custom-made insoles on plantar pressures and load redistribution in neuropathic diabetic patients with foot deformity. Cross-sectional. Although custom-made insoles are commonly prescribed to diabetic patients, little quantitative data on their mechanical action exists. Regional in-shoe peak pressures and force-time integral...