Gait analysis is the systematic study of
animal locomotionAnimal locomotion, which is the act of self-propulsion by an animal, has many manifestations, including running, swimming, jumping and flying. Animals move for a variety of reasons, such as to find food, a mate, or a suitable microhabitat, and to escape predators...
, more specific as a study of human motion, using the eye and the brain of observers, augmented by
instrumentationInstrumentation is defined as the art and science of measurement and control of process variables within a production, or manufacturing area....
for measuring body movements,
body mechanicsBiomechanics is the application of mechanical principles to biological systems, such as humans, animals, plants, organs, and cells. Perhaps one of the best definitions was provided by Herbert Hatze in 1974: "Biomechanics is the study of the structure and function of biological systems by means of...
, and the activity of the muscles. Gait analysis is used to assess, plan, and treat individuals with conditions affecting their ability to walk. It is also commonly used in
sports biomechanicsSports biomechanics is a quantitative based study and analysis of professional athletes and sports' activities in general. It can simply be described as the Physics of Sports...
to help athletes run more efficiently and to identify posture-related or movement-related problems in people with injuries.
The study encompasses
quantificationQuantification has several distinct senses. In mathematics and empirical science, it is the act of counting and measuring that maps human sense observations and experiences into members of some set of numbers. Quantification in this sense is fundamental to the scientific method.In logic,...
, i.e. introduction and analysis of measurable parameters of
gaitGait is the pattern of movement of the limbs of animals, including humans, during locomotion over a solid substrate. Most animals use a variety of gaits, selecting gait based on speed, terrain, the need to maneuver, and energetic efficiency...
s, as well as interpretation, i.e. drawing various conclusions about the animal (health, age, size, weight, speed, etc.) from its gait.
History
The pioneers of scientific gait analysis were Aristotle in
De Motu Animalium (On the Gait of Animals) and much later in 1680,
Giovanni Alfonso BorelliGiovanni Alfonso Borelli was a Renaissance Italian physiologist, physicist, and mathematician. He contributed to the modern principle of scientific investigation by continuing Galileo's custom of testing hypotheses against observation...
also called
De Motu Animalium (I et II). In the 1890s, the German anatomist
Christian Wilhelm BrauneChristian Wilhelm Braune was a German anatomist and professor of topographical anatomy at the University of Leipzig. He is known for his excellent lithographs regarding cross-sections of the human body, and his pioneer work in biomechanics...
and Otto Fischer published a series of papers on the biomechanics of human gait under loaded and unloaded conditions.
With the development of
photographyPhotography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...
, it became possible to capture image sequences which reveal details of human and animal locomotion that are not noticeable by watching the movement with the naked eye.
Eadweard MuybridgeEadweard J. Muybridge was an English photographer who spent much of his life in the United States. He is known for his pioneering work on animal locomotion which used multiple cameras to capture motion, and his zoopraxiscope, a device for projecting motion pictures that pre-dated the flexible...
and
Étienne-Jules MareyÉtienne-Jules Marey was a French scientist and chronophotographer.His work was significant in the development of cardiology, physical instrumentation, aviation, cinematography and the science of labor photography...
were pioneers of this in the early 1900s. It was photography which first revealed the detailed sequence of the horse "gallop" gait, which is usually mis-represented in paintings made prior to this discovery, for example.
Although much early research was done using
film camerasThe movie camera is a type of photographic camera which takes a rapid sequence of photographs on strips of film which was very popular for private use in the last century until its successor, the video camera, replaced it...
, the widespread application of gait analysis to humans with pathological conditions such as
cerebral palsyCerebral palsy is an umbrella term encompassing a group of non-progressive, non-contagious motor conditions that cause physical disability in human development, chiefly in the various areas of body movement....
,
Parkinson's diseaseParkinson's disease is a degenerative disorder of the central nervous system...
, and
neuromuscular disorderNeuromuscular disease is a very broad term that encompasses many diseases and ailments that either directly, via intrinsic muscle pathology, or indirectly, via nerve pathology, impair the functioning of the muscles....
s, began in the 1970s with the availability of
video cameraA video camera is a camera used for electronic motion picture acquisition, initially developed by the television industry but now common in other applications as well. The earliest video cameras were those of John Logie Baird, based on the electromechanical Nipkow disk and used by the BBC in...
systems which could produce detailed studies of individual patients within realistic cost and time constraints. The development of treatment regimes, often involving orthopaedic surgery, based on gait analysis results, advanced significantly in the 1980s. Many leading orthopaedic
hospitalA hospital is a health care institution providing patient treatment by specialized staff and equipment. Hospitals often, but not always, provide for inpatient care or longer-term patient stays....
s worldwide now have gait labs which are routinely used in large numbers of cases, both to design treatment plans, and for follow-up monitoring.
Development of modern computer based systems occurred independently during the late 1970s and early 1980s in several hospital based research labs, some through collaborations with the aerospace industry. Commercial development soon followed with the emergence of Vicon Motion Systems and BTS, marketing gait analysis hardware systems in the mid-1980s.
Equipment and techniques
Gait analysis commonly involves the measurement of the movement of the body in space (kinematics) and the forces involved in producing these movements (
kineticsIn physics and engineering, kinetics is a term for the branch of classical mechanics that is concerned with the relationship between the motion of bodies and its causes, namely forces and torques...
).
KinematicsKinematics is the branch of classical mechanics that describes the motion of bodies and systems without consideration of the forces that cause the motion....
can be recorded using a variety of systems and methodologies:
- Chronophotography
Chronophotography is an antique photographic technique from the Victorian era , which captures movement in several frames of print. These prints can be subsequently arranged either like animation cels or layered in a single frame...
is the most basic method for the recording of movement. Strobe lighting at known frequency has been used in the past to aid in the analysis of gait on single photographic images.
- Cine film
Ciné is usually used to refer to one or more of the home movie formats including 8 mm, 9.5 mm, 16 mm film, and Super 8. It is not generally used to refer to video formats or professional formats ....
or videoVideo is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.- History :...
recordings using footage from single or multiple cameras can be used to measure joint angles and velocities. This method has been aided by the development of analysis software that greatly simplifies the analysis process and allows for analysis in three dimensions rather than two dimensions only.
- Passive marker systems, using reflective markers (typically reflective balls), allows for very accurate measurement of movements using multiple cameras (typically five to twelve cameras), simultaneously. The cameras utilize high-powered strobes (typically red, near infrared or infrared) with matching filters to record the reflection from the markers placed on the body. Markers are located at palpable anatomical landmarks. Based on the angle and time delay between the original and reflected signal, triangulation of the marker in space is possible. Software is used to create three dimensional trajectories from these markers which are subsequently given identification labels. A computer model is then used to compute joint angles from the relative marker positions of the labeled trajectories. These are also used for motion capture
Motion capture, motion tracking, or mocap are terms used to describe the process of recording movement and translating that movement on to a digital model. It is used in military, entertainment, sports, and medical applications, and for validation of computer vision and robotics...
in the motion picture industry.
- Active marker systems are similar to the passive marker system but use "active" markers. These markers are triggered by the incoming infra red signal and respond by sending out a corresponding signal of their own. This signal is then used to triangulate the location of the marker. The advantage of this system over the passive one is that individual markers work at predefined frequencies and therefore, have their own "identity". This means that no post-processing of marker locations is required, however, the systems tend to be less forgiving for out-of-view markers than the passive systems.
- Inertial (cameraless) systems based on MEMS inertial sensors, biomechanical models, and sensor fusion algorithms. These full-body or partial body systems can be used indoors and outdoors regardless of lighting conditions.
A typical modern gait lab has several to many cameras (video and/or infrared) placed around a walkway or treadmill, which are linked to a computer. The patient has single markers applied to anatomical landmarks, such as palpable bony landmarks (e.g., the iliac spines of the
pelvisIn human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
, the
malleoliEach leg is supported by two bones, the tibia on the inner side of the leg and the fibula on the outer side of the leg.The medial malleolus is the prominence on the inner side of the ankle, formed by the lower end of the tibia....
of the
ankleThe ankle joint is formed where the foot and the leg meet. The ankle, or talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus bone in the foot...
, and the condyles of the
kneeThe knee joint joins the thigh with the leg and consists of two articulations: one between the fibula and tibia, and one between the femur and patella. It is the largest joint in the human body and is very complicated. The knee is a mobile trocho-ginglymus , which permits flexion and extension as...
), or clusters of markers applied to the middle of body segments. The patient walks down the walkway or the treadmill and the computer calculates the trajectory of each marker in three dimensions. A model is applied to compute the underlying motion of the bones. This gives a full breakdown of the motion at each joint.
In addition, to calculate movement
kineticsIn physics and engineering, kinetics is a term for the branch of classical mechanics that is concerned with the relationship between the motion of bodies and its causes, namely forces and torques...
, most laboratories have floor-mounted
load transducersA load cell is a transducer that is used to convert a force into electrical signal. This conversion is indirect and happens in two stages. Through a mechanical arrangement, the force being sensed deforms a strain gauge. The strain gauge measures the deformation as an electrical signal, because the...
, also known as
force platformForce 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.The simplest force...
s, which measure the ground reaction forces and moments, including magnitude, direction, and location (called
centre of pressureThe center of pressure is the point on a body where the total sum of a pressure field acts, causing a force and no moment about that point. The total force vector acting at the center of pressure is the value of the integrated vectorial pressure field. The resultant force and center of pressure...
). The spatial distribution of forces can also be measured using
pedobarographicPedobarography 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...
equipment. Adding this to the known dynamics of each body segment, enables the solution of equations based on the Newton–Euler equations of motion permitting computations of the net forces and the net moments of force about each joint at every stage of the gait cycle. The computational method for this is known as
inverse dynamicsInverse dynamics is an inverse problem. It commonly refers to either inverse rigid body dynamics or inverse structural dynamics. Inverse rigid-body dynamics is a method for computing forces and/or moments of force based on the kinematics of a body and the body's inertial properties...
.
This use of kinetics, however, does not result in information for individual muscles but muscle groups, such as the extensor or flexors of the limb. To detect the activity and contribution of individual muscles to movement, it is necessary to investigate the electrical activity of muscles. Many labs also use surface electrodes attached to the skin to detect the electrical activity or electromyogram (EMG) of, for example, a muscles of the leg. In this way it is possible to investigate the activation times of muscles and, to some degree, the magnitude of their activation—thereby assessing their contribution to gait. Deviations from normal kinematic,
kineticIn physics and engineering, kinetics is a term for the branch of classical mechanics that is concerned with the relationship between the motion of bodies and its causes, namely forces and torques...
, or
EMGElectromyography is a technique for evaluating and recording the electrical activity produced by skeletal muscles. EMG is performed using an instrument called an electromyograph, to produce a record called an electromyogram. An electromyograph detects the electrical potential generated by muscle...
patterns are used to diagnose specific pathologies, predict the outcome of treatments, or determine the effectiveness of training programs.
Medical diagnostics
Pathological gait may reflect compensations for underlying pathologies, or be responsible for causation of symptoms in itself. Cerebral palsy and stroke patients are commonly seen in gait labs. The study of gait allows diagnoses and intervention strategies to be made, as well as permitting future developments in
rehabilitation engineeringRehabilitation engineering is the systematic application of engineering sciences to design, develop, adapt, test, evaluate, apply, and distribute technological solutions to problems confronted by individuals with disabilities...
. Aside from clinical applications, gait analysis is used in professional sports training to optimize and improve athletic performance.
Gait analysis techniques allow for the assessment of gait disorders and the effects of corrective Orthopedic surgery. Options for treatment of cerebral palsy include the paralysis of spastic muscles using Botox or the lengthening, re-attachment or detachment of particular
tendonA tendon is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fasciae as they are all made of collagen except that ligaments join one bone to another bone, and fasciae connect muscles to other...
s. Corrections of distorted bony anatomy are also undertaken (
osteotomyAn osteotomy is a surgical operation whereby a bone is cut to shorten, lengthen, or change its alignment. It is sometimes performed to correct a hallux valgus, or to straighten a bone that has healed crookedly following a fracture. It is also used to correct a coxa vara, genu valgum, and genu varum...
).
It is used in the assessment of sports and investigations into the movement of a large variety of other animals.
Biometric identification and forensics
Minor variations in gait style can be used as a
biometric identifierBiometrics As Jain & Ross point out, "the term biometric authentication is perhaps more appropriate than biometrics since the latter has been historically used in the field of statistics to refer to the analysis of biological data [36]" . consists of methods...
to
identifyForensic identification is the application of forensic science, or "forensics", and technology to identify specific objects from the trace evidence they leave, often at a crime scene or the scene of an accident. Forensic means "for the courts"....
individual people. The parameters are grouped to spatial-temporal (step length, step width, walking speed, cycle time) and kinematic (joint rotation of the hip, knee and ankle, mean joint angles of the hip/knee/ankle, and thigh/trunk/foot angles) classes. There is a high correlation between step length and height of a person.
Gait analysis was proposed as authentication for portable electronic devices.
For slip and fall investigations, the incident walking surface slip resistance can be measured. The surface can be tested to identify if it is above or below accepted levels or slip thresholds.
The English XL slip meter, also known as a VIT (Variable Incidence Tribometer) is a leading edge portable "slip tester", which is designed to test the coefficient of friction or "slip index" on various walking surfaces, level or incline (even steps), under dry and wet (or otherwise contaminated) conditions by mimicking certain pedestrian biomechanical parameters. The objective measurements that can be analyzed and compared with "normal" walking forces and industry standards regarding flooring slip resistance.
Popular media
- G. K. Chesterton
Gilbert Keith Chesterton, KC*SG was an English writer. His prolific and diverse output included philosophy, ontology, poetry, plays, journalism, public lectures and debates, literary and art criticism, biography, Christian apologetics, and fiction, including fantasy and detective fiction....
premised one of his Father BrownFather Brown is a fictional character created by English novelist G. K. Chesterton, who stars in 52 short stories, later compiled in five books. Chesterton based the character on Father John O'Connor , a parish priest in Bradford who was involved in Chesterton's conversion to Catholicism in 1922...
mysteries, "The Queer Feet", on gait recognition.
- Cory Doctorow
Cory Efram Doctorow is a Canadian-British blogger, journalist, and science fiction author who serves as co-editor of the blog Boing Boing. He is an activist in favour of liberalising copyright laws and a proponent of the Creative Commons organization, using some of their licences for his books...
makes much of gait recognition as a security technique used in a high school in his book Little BrotherLittle Brother is a novel by Cory Doctorow, published by Tor Books. It was released on April 29, 2008. The novel is about several teenagers in San Francisco who, in the aftermath of a terrorist attack on the San Francisco – Oakland Bay Bridge and BART system, defend themselves against the...
.
See also
- Gait Analysis: Normal and Pathological Function, Second Edition
Gait Analysis: Normal and Pathological Function, Second Edition is a textbook that focuses on human gait analysis and is written by Drs. Jacquelin Perry and Judith M. Burnfield. It is an updated and revised version of Gait Analysis: Normal and Pathological Function , a text many consider to be a...
- Gait Abnormality Rating Scale
Gait Abnormality Rating Scale is a videotape-based analysis of 16 facets of human gait. It has been evaluated as a screening tool to identify patients at risk for injury from falls. and has been used in remote gait evaluation...
- Terrestrial locomotion in animals
Terrestrial locomotion has evolved as animals adapted from aquatic to terrestrial environments. Locomotion on land raises different problems than that on water, with reduced friction being replaced by the effects of gravity....
External links