GAIT CYCLE & CLINICAL GAIT ANALYSIS
- 1. CLINICAL GAIT ANALYSIS PRESENTED BY: FIONA VERMA MPO 1ST YEAR, 2023 ROLL NO: 03 6TH BATCH 1
- 2. CONTENTS • GAIT CYCLE • CYCLE DIVISIONS • STRIDE AND STEP LENGTH • DIVISIONS OF GAIT CYCLE • WEIGHT ACCEPTANCE • SINGLE LIMB SUPPORT • LIMB ADVANCEMENT • CLINICAL GAIT ANAYSIS • VISUAL GAIT ANAYSIS • GAIT ASSESSMENT • EXAMINATION BY VIDEO RECORDING • TEMPORAL-DISTANCE GAIT PARAMETERS 2
- 3. • TIMING THE GAIT CYCLE • FOOTSWITCHES • CONDUCTIVE WALKWAYS • ELECTROGONIOMETERS • POTENTIOMETER • FLEXIBLE STRAIN GAUGES • PRESSURE BENEATH THE FOOT • GLASS PLATE EXAMINATION • PEDOBAROGRAPH • FORCE SENSOR SYSTEM • ELECTROMYOGRAPHY • SURFACE ELECTRODES • FINE WIRE • NEEDLE ELECTRODES • FORCE PLATFORMS • KINEMATIC GAIT ANAYSIS SYSTEMS • ACTIVE MARKER SYSTEM 3
- 4. GAIT CYCLE • A gait cycle spans two successive events of the same extremity. During one gait cycle, each extremity passes through two major phases: a stance phase (one limb serves as a mobile source of support) and a swing phase (while other limb advances itself to new support site), then the limb reverse their role. This series of event is repeated by each limb. CYCLE DIVISIONS STANCE 60% SWING 40% INITIAL DOUBLE STANCE 10% SINGLE LIMB SUPPORT 40% TERMINAL DOUBLE SUPPORT 10% 4
- 5. STRIDE AND STEP LENGTH: The gait cycle also has been identified by the descriptive term stride. i.e. stride is equivalent of a gait cycle. 5
- 6. DIVISION OF GAIT CYCLE GAIT CYCLE STANCE SWING WEIGHT ACCEPTANCE SINGLE LIMB SUPPORT LIMB ADVANCEMENT INITIAL CONTACT LOADING RESPONSE MID STANCE TERMINAL STANCE PRE SWING INITIAL SWING MID SWING TERMINAL SWING PERIODS TASKS PHASES 6
- 7. WEIGHT ACCEPTANCE GAIT PHASE GC INTERVAL OBJECTIVE HIP KNEE ANKLE INITIAL CONTACT 0-2% The limb is positioned to start stance with a heel rocker 30 ֯ O-5 ֯ 90 ֯ OR 0 LOADING RESPONSE 0-10% • Shock-absorption • Weight- bearing • Preservation of progression 20 ֯ flexion 15-20 ֯ flexion 5-10 ֯ PF 7
- 8. SINGLE LIMB SUPPORT GAIT PHASE GC INTERVAL OBJECTIVE HIP KNE E ANKLE MID STANCE 10-30% • Progression over stationary foot • Limb and trunk stability 0 ֯ O-5 ֯ flex 5 ֯ DF TERMINAL STANCE 30-50% • Progression of body beyond the supporting foot -20 ֯ hyper- extension 0-5 ֯ flex 10 ֯ DF 8
- 9. LIMB ADVANCEMENT GAIT PHASE GC INTERVAL OBJECTIVE HIP KNEE ANKLE PRE-SWING 50-60% • Position the limb for Swing -10 ֯ HE 40 ֯ flexion 15 ֯ PF INITIAL SWING 60-73% • Foot clearance of the floor • Advancement of the limb from it’s trailing position 15 ֯ flexion 60-70 ֯ flexion 10 ֯ DF MID SWING 73-87% • Limb advancement • Foot clearance from the floor 20 ֯ flexion 30֯ flexion 0 ֯ TERMINAL SWING 87-100% • Complete limb advancement • Prepare the limb for stance 30 ֯ flexion 0-5 ֯ flexion 0 ֯ -3 ֯ DF 9
- 10. CLINICAL GAIT ANALYSIS Gait analysis is used for two very different purposes: • To aid directly in the treatment of individual patients • To improve our understanding of gait through research. There are several methods which starts with no equipment required to progressively elaborate systems:- 1. Visual gait analysis • Gait assessment • Examination by video-taping • Temporal-distance gait parameters 2. Timing gait cycle (footswitches and instrumented walkways) 3. Electro-goniometers • Potentiometer devices • Flexible strain gauges 10
- 11. 5. Electromyography • Surface electrodes • Fine wire electrodes • Needle electrodes 7. Force platforms 8. Kinematic analysis system 11
- 12. VISUAL GAIT ANAYSIS Simplest form of gait analysis made by unaided human eye. It is the most complicated & versatile form of analysis. Limitations of VGA: It is giving no permanent record The eye cannot observe high-speed events Only movements, not forces Depends on skills of the observer A thorough visual gait analysis involves watching the subject while he/she makes numbers of walk, some of which are observed from : • Both the sides • Front • back 12 reference: Gait Analysis, Michael W. Whittle, Fourth Edition
- 13. • Minimum length required for gait analysis walkway is kept about 8m (26ft) which is minimum for use with fit young people. • The width required for walkway depends on what equipment if any is being used to make measurements. Layout of a small gait laboratory for Visual Gait Analysis, videotaping and measurement of general gait parameters. 13
- 14. GAIT ASSESSMENT • Simply observing the gait and noting abnormalities but is of little value itself. • It needs to be followed by gait assessment, which is the synthesis of gait observations with other information about the subject from history & physical examination. • Visual gait analysis is entirely subjective & the quality depends on the skill of the person performing it. Common gait abnormalities and their observation direction Gait abnormalities Observing direction Lateral trunk bending Front or back Anterior trunk bending Front or back Posterior trunk bending Front or back Increased lumbar lordosis Side Circumduction Front or back Hip hiking Front or back Excessive knee flexion/extension Side Abnormal walking base Front or back 14
- 15. EXAMINATION BY VIDEO RECORDING • The widespread use of video recording and direct recording to a DVD, memory card or computer became useful enhancement to gait analysis. • It helps to overcome two limitations of visual gait analysis: • Lack of a permanent record • Difficulty observing high-speed event 15
- 16. When using videotape, the most practical system consists of a Camera-recorder also know as Camcorder and a separate VCR to replay the tapes. The requirements of camcorders are: • Zoom lens • Automatic focus • The ability to operate in normal room lighting • An electronically shuttered CCD sensor, to eliminate blurring due to movement. Now, many gait laboratories record video data directly into a computer. It is often possible to enhance visibility of anatomical landmarks on the recording- by marking subject’s skin. 16
- 17. TEMPORAL-DISTANCE PARAMETERS • Temporal –distance parameters are general gait parameters including cycle time or cadence, stride length and speed. • It is the simplest form of objective gait evaluation and use only stopwatch, tape measure and optionally talcum powder. 1. Cycle time or cadence measurement: Measured with the aid of a stopwatch, by counting number of individual steps taken during a known period of time. Cycle time (s) = time (s) × 2/ steps counted Cadence is calculated using the formula: Cadence(steps/min) = steps counted × 60/time(s) 17
- 18. 2. Stride length: Stride length can be measured by 2 ways: direct and indirect method. Direct method: Simply by measuring the strides taken while the subject covers a known distance. For this, the subject will dip both feet in talcum powder & then walk across a polished floor or a strip of brown/colored paper – leaving trail of footprints. Left & right Stride length is then measured. Left and right Step length, walking width and toe out angle can also measured with this method. 18
- 19. • Indirect method to measure stride length: If both the cycle time and the speed have been measured, stride length may be calculated using the formula: Stride length (m) = speed (m/s) × cycle time (s) The equivalent calculation using cadence is:- Stride length (s) = speed (m/s) × 2 × 60/ cadence (steps/min) 3. Speed: The speed is measured by timing the subject while he or she walks a known distance e.g. between two marks on the floor or between two pillars in a corridor. The distance walked is as per convenience but it should be in the region of 6-10m The speed is calculated as follows: Speed(m/s) = distance (m)/ time(s) 19
- 20. TIMING THE GAIT CYCLE Number of systems are available to automatically measure the timing of gait cycle. It is divided into 2 classes:- • Foot switches • Instrumented walkways Footswitches: • one footswitch is fixed beneath the heel and one beneath the forefoot will measure the timing of initial contact, heel-rise and toe-off and the duration of the stance phase. • Data from two or more strides will calculate the cycle time and swing phase timing. 20
- 21. • Various designs are made to make them reliable as these foot switches are exposed to high forces. • Output obtained from the device is show in the fig below. Output from Footswitch under heel, 4 metatarsals and hallux of both feet 21
- 22. Instrumented walkways: • conductive walkway: Covered with electrically conductive substance with suitably positioned electrical contacts on the subject’s shoes to complete the electrical circuit. Timing information from foot contact is used to calculate the temporal & spatial gait parameters. • Walkways with embedded switch contact: Alternative arrangement is to have the walkway itself contain a large number of switch contact, which will detect the position of the foot. Some commercial systems also provide information on the magnitude of forces b/w foot and ground. Fig: GAIT-Rite Walkway 22
- 23. ELECTROGONIOMETERS An electrogoniometer is a device for making continuous measurements of the angle of the joint. Output of an electrogoniometer is usually plotted as a chart of joint angle against time. They are of different designs: • Potentiometer • Flexible strain gauges Potentiometer devices: A rotary potentiometer is a variable resistor of the type in which turning the central spindle produces a change in electrical resistance, which can be measured by an external circuit. The position of potentiometer is adjusted to be as close to the joint axis as possible. Fig: subject is wearing triaxial goniometer on hip, knee and ankle 23
- 24. Flexible strain gauges electrogoniometer: The flexible strain gauge consists of a flat, thin strip of metal, one end of which is fixed to the limb on each side of the joint being studied. The bending of the metal as the joint moves is measured by strain gauges and their associated electronics. To measure more than one axis, a two-axis goniometer may be used, or 2 or 3 separate goniometers may be fixed around the joint. 24
- 25. PRESSURE BENEATH THE FOOT The measurement of the pressure beneath the foot is a specialized form of gait analysis, which may be of particular value in conditions in which pressure is uneven e.g. excessive pressure in diabetic neuropathy. The SI unit for pressure is the Pascal (Pa). Practically measurements are made in kilopascals (kPa) or megapascals (MPa). Typical pressures beneath the foot are: • 80-100 kPa in standing • 200-500 kPa in walking up to 1500 kPa in some sporting activities. Methods used to measure such pressure beneath foot:- Glass plate examination Pedobargraph Force sensor system 25
- 26. Glass plate examination: Semi-quantitative information on the pressure beneath the foot can be obtained by having the subject stand on or walk across, a glass plate which is viewed below the subject using mirror or camera. It is easy to see which areas of the sole of foot comes into contact with the walking surface. Pedobarograph: The pedobarograph uses an elastic mat, laid on top of an edge-lit glass plate. When subject walks on the mat it is compressed onto the glass, which loses its reflectivity, becoming progressively darker with increasing pressure. This darkening provides the means for quantitative measurement. Force sensor system: Subject walks across an array of force sensors, each of which measures the vertical force beneath a particular area of the foot. Glass plate examination Force sensor system 26
- 27. ELECTROMYOGRAPHY Electromyography (EMG) is the measurement of the electrical activity of a contracting muscle, which is often referred to as the motor unit action potential (MUAP). Since it is a measure of electrical and not mechanical activity, the EMG cannot be used to distinguish between concentric, isometric and eccentric contractions. It is particularly good in determining the onset and termination of various muscles contraction during gait cycle analysis. 3 method of recording the EMG: • Surface electrodes • Fine wire electrodes • Needle electrodes 27
- 28. Surface electrodes: Surface EMG is by far the most widely used method for gait analysis. Surface electrodes are fixed to the skin over the muscle. Most of the signal comes from within 25mm of the skin surface, so this type of recording is not suitable for deep muscles such as iliopsoas. Fine wire electrodes: Fine wire electrodes are introduces directly into a muscle, using a hypodermic needle which is then withdrawn, leaving the wires in place. Needle electrodes: A hypodermic needle is used, this record EMG signal from a very local area within the muscle into which it is inserted, usually a single motor unit. 28
- 29. FORCE PLATFORM SYSTEM The force platform which is known as ‘force-plate’ is used to measure the ground reaction force acting as the subjects walk on it. The typical design of force-plate is about 100mm high with a flat rectangular upper surface measuring 400mm by 600mm. The sensors are placed in different orientations enabling the direction and magnitude of forces in all 3 axis to be obtained. 29
- 30. KINEMATIC SYSTEMS Kinematic is the measurement of movement or more specifically the geometric description of motion. This system is used in gait analysis to record the position and orientation of the body segments, the angles of joints and corresponding linear and angular velocities and accelerations. Active marker system: • Use of active marker system typically LEDs and a special optoelectronic camera. Typically, these systems use invisible infra-red radiation. • The camera measures the position of the marker by analyzing the light coming from it. • The LEDs are arranged to flash on and off in sequence, so that one is illuminated at any instant of time. 30
- 31. THANK YOU 31