Pedobarography | |
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Test of | gait biomechanics |
Pedobarography is the study of pressure fields acting between the plantar surface of the foot and a supporting surface. Used most often for biomechanical analysis of gait and posture, pedobarography is employed in a wide range of applications including sports biomechanics and gait biometrics. The term 'pedobarography' is derived from the Latin: pedes, referring to the foot (as in: pedometer, pedestrian, etc.), and the Greek: baros meaning 'weight' and also 'pressure' (as in: barometer, barograph).
The first documented pedobarographic study was published in 1882 and used rubber and ink to record foot pressures. [1] Numerous studies using similar apparatus were conducted in the early- and mid-twentieth century, [1] [2] but it was not until the advent of the personal computer that electronic apparatus were developed and that pedobarography became practical for routine clinical use. [3] It is now used widely to assess and correct a variety of biomechanical and neuropathic disorders. [4] [5]
Devices fall into two main categories: (i) floor-based, and (ii) in-shoe. The underlying technology is diverse, ranging from piezoelectric sensor arrays to light refraction, [2] [4] [6] [7] [8] but the ultimate form of the data generated by all modern technologies is either a 2D image or a 2D image time series of the pressures acting under the plantar surface of the foot. Currently, there are several commercial pressure measurement systems and they generally use capacitive or resistive sensors. [9] Studies have shown that capacitive sensors are more valid and reliable than resistive sensors when used continuously for a longer period of time. [10] From these data other variables may be calculated (see Data analysis).
There are a few differences between the types of information you will receive from these two systems, so depending on the application one system might be a better fit. For example, a floor-based system will provide spatial temporal information, like stride length that an in-shoe system cannot provide. Platform systems (or floor-based systems) will also allow for testing of patients with walking aids for assistive devices. However, there is some controversy about evaluating natural gait with a platform system due to patients potentially targeting the platform when walking. This is where an in-shoe system provides an advantage as it reduces the risk of targeting. Users should evaluate carefully the differences between the systems, the patients they will be evaluating and the type of data they are interested in when selecting a system. [11]
The spatial and temporal resolutions of the images generated by commercial pedobarographic systems range from approximately 3 to 10 mm and 25 to 500 Hz, respectively. Finer resolution is limited by sensor technology. Such resolutions yield a contact area of approximately 500 sensors (for a typical adult human foot with surface area of approximately 100 cm2). [12] For a stance phase duration of approximately 0.6 seconds during normal walking, [13] approximately 150,000 pressure values, depending on the hardware specifications, are recorded for each step.
To deal with the large volume of data contained in each pedobarographic record, traditional analyses reduce the data to a more manageable size in three stages: (1) produce anatomical or regional masks, (2) extract regional data, and (3) run statistical tests. Results are typically reported in tabular or bar graph formats. There are also a number of alternative analysis techniques derived from digital image processing methodology. [14] [15] [16] These techniques have also been found to be clinically and biomechanically useful, but traditional regional analyses are most common.
The most commonly analyzed pedobarographic variable is 'peak pressure', or the maximum pressure experienced at each sensor (or pixel, if the sensors fall on a regular square grid) over the duration of the step. Other variables like contact duration, pressure-time integral, center of pressure trajectory, for example, are also relevant to the biomechanical function of the foot.
The most widely researched clinical application of pedobarography is diabetic foot ulceration, [17] a condition which can lead to amputation in extreme cases [18] but for which even mild-to-moderate cases are associated with substantial health care expenditure. [19] Pedobarography is also used in a variety of other clinical situations including: post-surgery biomechanical assessment, [20] intra-operative assessment, [21] orthotics design [22] and assessment of drop-foot surgery. [5] In addition to clinical applications, pedobarography continues to be used in the laboratory to understand the mechanisms governing human gait and posture. [3] [7]
The use of pedobarographs in clinical settings is supported by researchers. According to Bowen, et al., "Pediobarograph measurements can be used to monitor and quantitatively assess the progressive changes of foot deformity over time. Pedobarograph is a reliable measurement that shows little variability between measurements at the same occasion and between measurements on different days." [23]
Anthropometry refers to the measurement of the human individual. An early tool of physical anthropology, it has been used for identification, for the purposes of understanding human physical variation, in paleoanthropology and in various attempts to correlate physical with racial and psychological traits. Anthropometry involves the systematic measurement of the physical properties of the human body, primarily dimensional descriptors of body size and shape. Since commonly used methods and approaches in analysing living standards were not helpful enough, the anthropometric history became very useful for historians in answering questions that interested them.
Gait analysis is the systematic study of animal locomotion, more specifically the study of human motion, using the eye and the brain of observers, augmented by instrumentation for measuring body movements, body mechanics, and the activity of the muscles. Gait analysis is used to assess and treat individuals with conditions affecting their ability to walk. It is also commonly used in sports biomechanics to help athletes run more efficiently and to identify posture-related or movement-related problems in people with injuries.
Diabetic neuropathy is various types of nerve damage associated with diabetes mellitus. Symptoms depend on the site of nerve damage and can include motor changes such as weakness; sensory symptoms such as numbness, tingling, or pain; or autonomic changes such as urinary symptoms. These changes are thought to result from a microvascular injury involving small blood vessels that supply nerves. Relatively common conditions which may be associated with diabetic neuropathy include distal symmetric polyneuropathy; third, fourth, or sixth cranial nerve palsy; mononeuropathy; mononeuropathy multiplex; diabetic amyotrophy; and autonomic neuropathy.
The plantar fascia or plantar aponeurosis is the thick connective tissue aponeurosis which supports the arch on the bottom of the foot. Recent studies suggest that the plantar fascia is actually an aponeurosis rather than true fascia. It runs from the tuberosity of the calcaneus forward to the heads of the metatarsal bones.
Plantar fasciitis or plantar heel pain is a disorder of the plantar fascia, which is the connective tissue which supports the arch of the foot. It results in pain in the heel and bottom of the foot that is usually most severe with the first steps of the day or following a period of rest. Pain is also frequently brought on by bending the foot and toes up towards the shin. The pain typically comes on gradually, and it affects both feet in about one-third of cases.
A gait is a manner of limb movements made during locomotion. Human gaits are the various ways in which humans can move, either naturally or as a result of specialized training. Human gait is defined as bipedal forward propulsion of the center of gravity of the human body, in which there are sinuous movements of different segments of the body with little energy spent. Varied gaits are characterized by differences such as limb movement patterns, overall velocity, forces, kinetic and potential energy cycles, and changes in contact with the ground.
Sensor fusion is the process of combining sensor data or data derived from disparate sources such that the resulting information has less uncertainty than would be possible when these sources were used individually. For instance, one could potentially obtain a more accurate location estimate of an indoor object by combining multiple data sources such as video cameras and WiFi localization signals. The term uncertainty reduction in this case can mean more accurate, more complete, or more dependable, or refer to the result of an emerging view, such as stereoscopic vision.
The arches of the foot, formed by the tarsal and metatarsal bones, strengthened by ligaments and tendons, allow the foot to support the weight of the body in the erect posture with the least weight.
A facultative biped is an animal that is capable of walking or running on two legs (bipedal), as a response to exceptional circumstances (facultative), while normally walking or running on four limbs or more. In contrast, obligate bipedalism is where walking or running on two legs is the primary method of locomotion. Facultative bipedalism has been observed in several families of lizards and multiple species of primates, including sifakas, capuchin monkeys, baboons, gibbons, gorillas, bonobos and chimpanzees. Different facultatively bipedal species employ different types of bipedalism corresponding to the varying reasons they have for engaging in facultative bipedalism. In primates, bipedalism is often associated with food gathering and transport. In lizards, it has been debated whether bipedal locomotion is an advantage for speed and energy conservation or whether it is governed solely by the mechanics of the acceleration and lizard's center of mass. Facultative bipedalism is often divided into high-speed (lizards) and low-speed (gibbons), but some species cannot be easily categorized into one of these two. Facultative bipedalism has also been observed in cockroaches and some desert rodents.
A removable shoe insert, otherwise known as a foot orthosis, insole or inner sole, accomplishes many purposes, including daily wear comfort, height enhancement, plantar fasciitis treatment, arch support, foot and joint pain relief from arthritis, overuse, injuries, leg length discrepancy, and other causes such as orthopedic correction and athletic performance.
Balance in biomechanics, is an ability to maintain the line of gravity of a body within the base of support with minimal postural sway. Sway is the horizontal movement of the centre of gravity even when a person is standing still. A certain amount of sway is essential and inevitable due to small perturbations within the body or from external triggers. An increase in sway is not necessarily an indicator of dysfunctional balance so much as it is an indicator of decreased sensorimotor control.
Force platforms or force plates are measuring instruments that measure the ground reaction forces generated by a body standing on or moving across them, to quantify balance, gait and other parameters of biomechanics. Most common areas of application are medicine and sports.
Diabetic shoes are specially designed shoes, or shoe inserts, intended to reduce the risk of skin breakdown in diabetics with existing foot disease and relieve pressure to prevent diabetic foot ulcers.
Orthotics is a medical specialty that focuses on the design and application of orthoses, sometimes known as braces or calipers. An orthosis is "an externally applied device used to influence the structural and functional characteristics of the neuromuscular and skeletal systems." Orthotists are professionals who specialize in designing these braces.
Parkinsonian gait is the type of gait exhibited by patients with Parkinson's disease (PD). It is often described by people with Parkinson's as feeling like being stuck in place, when initiating a step or turning, and can increase the risk of falling. This disorder is caused by a deficiency of dopamine in the basal ganglia circuit leading to motor deficits. Gait is one of the most affected motor characteristics of this disorder although symptoms of Parkinson's disease are varied.
In biomechanics, center of pressure (CoP) is the term given to the point of application of the ground reaction force vector. The ground reaction force vector represents the sum of all forces acting between a physical object and its supporting surface. Analysis of the center of pressure is common in studies on human postural control and gait. It is thought that changes in motor control may be reflected in changes in the center of pressure. In biomechanical studies, the effect of some experimental condition on movement execution will regularly be quantified by alterations in the center of pressure.
Neuromechanics of orthoses refers to how the human body interacts with orthoses. Millions of people in the U.S. suffer from stroke, multiple sclerosis, postpolio, spinal cord injuries, or various other ailments that benefit from the use of orthoses. Insofar as active orthoses and powered exoskeletons are concerned, the technology to build these devices is improving rapidly, but little research has been done on the human side of these human-machine interfaces.
Diabetic foot ulcer is a breakdown of the skin and sometimes deeper tissues of the foot that leads to sore formation. It may occur due to a variety of mechanisms. It is thought to occur due to abnormal pressure or mechanical stress chronically applied to the foot, usually with concomitant predisposing conditions such as peripheral sensory neuropathy, peripheral motor neuropathy, autonomic neuropathy or peripheral arterial disease. It is a major complication of diabetes mellitus, and it is a type of diabetic foot disease. Secondary complications to the ulcer, such as infection of the skin or subcutaneous tissue, bone infection, gangrene or sepsis are possible, often leading to amputation.
X-ray motion analysis is a technique used to track the movement of objects using X-rays. This is done by placing the subject to be imaged in the center of the X-ray beam and recording the motion using an image intensifier and a high-speed camera, allowing for high quality videos sampled many times per second. Depending on the settings of the X-rays, this technique can visualize specific structures in an object, such as bones or cartilage. X-ray motion analysis can be used to perform gait analysis, analyze joint movement, or record the motion of bones obscured by soft tissue. The ability to measure skeletal motions is a key aspect to one's understanding of vertebrate biomechanics, energetics, and motor control.
Gait deviations are nominally referred to as any variation of standard human gait, typically manifesting as a coping mechanism in response to an anatomical impairment. Lower-limb amputees are unable to maintain the characteristic walking patterns of an able-bodied individual due to the removal of some portion of the impaired leg. Without the anatomical structure and neuromechanical control of the removed leg segment, amputees must use alternative compensatory strategies to walk efficiently. Prosthetic limbs provide support to the user and more advanced models attempt to mimic the function of the missing anatomy, including biomechanically controlled ankle and knee joints. However, amputees still display quantifiable differences in many measures of ambulation when compared to able-bodied individuals. Several common observations are whole-body movements, slower and wider steps, shorter strides, and increased sway.