Gait Introduction 2024 PDF

DPT 512: Biomechanics/Kinesiology II Gait - Introduction Eric Folkins, PT, DPT, DHSC Nov 2024 Learning objectives After today’s class, the students will be able to: 1. Differentiate between walking & gait 2. Describe standard context for OGA (Observational Gait Analysis). 3. Describe 4 measuremen...

DPT 512: Biomechanics/Kinesiology II Gait - Introduction Eric Folkins, PT, DPT, DHSC Nov 2024 Learning objectives After today’s class, the students will be able to: 1. Differentiate between walking & gait 2. Describe standard context for OGA (Observational Gait Analysis). 3. Describe 4 measurement categories of biomechanical analysis of gait. 4. Describe how gait speed measure is affected by excluding acceleration/deceleration phases and distance used 5. Describe two components of gait speed. How they contribute to gait speed adjustment (including aging)? 6. Describe basic gait spatio-temporal variables 7. Describe gait phases using the Rancho Los Amigo terminology system Walking vs. Running A method of locomotion involving the use of the two legs, alternately, to provide both support and propulsion, at least one foot in contact with the ground at all times. Flight phase (a.k.a. double floating) This is observed during running, that there is time when no foot is in contact with the ground Walking – context matters Factors affecting individuals walk in a natural environmental factor External factors o Shoes (special case: high-heel, Scuba diving shoes) o Ambient light condition o Slippery floor o Walking in a crowd Internal factors o Age (details in lifespan course) o Gender o Habit, occupational training (such as ballerina) o Specific neurological, orthopedic diagnoses (details in neuro- ortho- courses) Intention or task-at-hand o Texting while walking o Holding a glass full of hot water Gait Pattern (joint posture/movements etc.) of how an individual walks. Each person tends to walk with a specific gait pattern. So gait pattern can be used as biometrics (e.g., forensic gait analysis) Pictures: Gait recognition using CCTV surveillance recording Gait Gait: The pattern (manner, style) of walking It is preferable to measure gait with a standardized protocol So comparison across clinics is meaningful Standardization of gait test is not always done in the clinic At least you need to be consistent with yourself Clinically, PT uses OGA (Observational Gait Analysis), which is limited to what can be observed by human eyes There are 4 categories of biomechanical measures for gait analysis only 1 category can be observed by eyes Precise measurement of gait will need instruments OGA (Observational Gait Analysis) Can’t observe all 4 categories of biomechanical gait analysis Kinematics (Observable by eyes) Kinetics (not observable by eyes) Muscle activity (not observable by eyes) Energy consumption (not observable by eyes) OGA accuracy depends on observers’ ability Need extensive training It is recommended to use standardized form to do OGA (We will use Rancho Los Amigo full body form) NPTE will have video tests (NPTE video items) Labs will provide opportunities to practice OGA using videos Standard context for OGA Speed to be tested (self-selected, fast, and slow) Control external factors that can affect gait Give clear instruction about task-at-hand Example: Walk straight and do not turn Walk along a straight line Example: Is it a good idea to take the straight-line walking of TUG (Timed-Up & Go) as standard gait test? No dual-task test for standardized gait test Examples of dual-task walking o Talking while walking o Counting numbers while walking Specified the distance used for gait test Gait speed (a.k.a. gait velocity) Most commonly reported gait variable Bears significant functional meaning Every OGA starts with a gait speed measurement All gait kinematics and temporospectral variables are affected by gait speed Gait speed bears significant functional meaning It is called the 6th vital sign for older adults Sensitive to mobility decline It predicts all-cause mortality It is a strong health-span predictor Strong association with past & future functional status Strong association with adverse health outcomes (such as falls) It predicts health care costs Gait speed interpretation - What is an appropriate norm to use for gait speed? Age Male Female Gender Age 20’s 3.57 3.47 ft/sec Population-specific 30’s 4.17 3.81 ft/sec (example: PD, THR) 40’s 3.72 3.53 ft/sec Ethnicity? 50’s 3.07 3.59 ft/sec Culture? 60’s 3.11 2.85 ft/sec Challenges for individual 70’s 3.08 2.79 ft/sec interpretation (especially for Frail 1.18 1.38 ft/sec diagnosis, prediction, as a biomarker) 1.1-1.2 m/s Lab Question 1 Gait speed test – Does it include acceleration, deceleration phases? Quiz as you learn – Which test method includes acceleration/deceleration? Quiz as you learn – Which test method will yield slower gait speed measurement? Gait speed measurement Speed Distance walked per unit time (distance/time) Unit: meter/second, ft/second Please calculate Mary walks 9 meters in 12 seconds, what is her gait speed? _____________ m/s Most people thinks it is very easy to measure gait speed Just need a space for walking, and stop watch In reality, many factors affect the measured gait speed o Do testers following the suggestion of a standardized gait test protocol? Reported gait speed varies a lot in published papers Each PT clinic should check their reliability in gait speed test 2 components of gait velocity 2 components of gait velocity  2 components of gait velocity - Cadence Cadence: Number of steps per unit of time Adult males: 111 steps/minute Adult females: 121 steps/minute Cadence itself is not a good measure of gait quality A patient with Parkinson's disease may show shuffling gait Which is many fast steps (i.e., high cadence) However, this patients may have very small step length Resulting is a very slow gait speed 2 components of gait velocity – Step length Step length: Distance between 2 consecutive steps Stride length: Distance between 2 steps of the same leg Average stride length ≈ 2 * Step length 2 components of gait velocity 2 components of gait velocity Lab Question 2 Lab Question 3 2 components of gait velocity – Men vs. women Gait speed (without normalization) Men walk faster than women Cadence Women have higher cadence Step length Men have longer step length Gait speed adjustment – increase step length or cadence? At the beginning of walking faster, ↑ cadence and ↑ stride length together At very high speed: ↑ cadence (step length reaches plateau) If continue to ↑ cadence : start to run Gait speed adjustment – Effect of aging Older people walk slower. Along the aging process, which component starts to decrease first? Basic spatial gait variables Foot placement determines spatial gait variables Normal width is 8-10 cm Normal toe out 8-10 degrees Basic spatial gait variables – Step length can be asymmetrical Right step length is longer than left step length Basic spatial gait variables – Step length can be negative Left side has a negative step length (step backward) Basic spatial gait variables – Step width can be negative Left side has a negative step width (cross-over step) https://youtu.be/1IsM08Sh_wg?t=9 Lab Question 4 Basic temporal gait variables Gait cycle time: Duration between two successive same events of the same limb (example: from Right heel strike to next right heel strike) Stance phase time: Duration when the leg is in contact with the floor (about 60% of gait cycle) Swing phase time: Duration when foot is not in contact with the floor (about 40% of gait cycle) Single stance (support) time: Duration when only one foot in contact with the floor (about 40% of gait cycle) Double stance (support) time: Duration when both legs are in contact with the floor (about 20% of the gait cycle) Double- single- stance, or swing? When R’t leg is in double stance, L’t leg is in double stance phase When R’t leg is in single stance, L’t leg is in swing Phase When L’t leg is in double stance, R’t leg is in double support phase When L’t leg is in single stance, R’t leg is in swing phase Gait cycle time Duration between two successive same events of the same limb (example: from Right heel strike to next right heel strike) Include one stride (1 step from right, 1 step from left) Gait cycle is about 1 to 1.1 seconds in healthy adults John has a cadence of 150 steps/minute, what is his average gait cycle time 1 ÷ (150 steps/minute ÷ 2 (steps/stride) ÷ 60 seconds/minute) = 1 ÷ (150/2/60) = 0.8 second/stride Time vs. % phase Gait phases are standardized to time by % Gait cycle starts @ 0%, ends @ 100% Robert has a gait cycle of 1.2 seconds Right leg is in contact with floor for 0.7 second o Right stance time is ? o Right stance phase % is ? Right leg is in the air for 0.5 second o Right stance time is ? o Right stance phase % is ? Time vs. % phase Gait phases are standardized to time by % Gait cycle starts @ 0%, ends @ 100% Robert has a gait cycle of 1.2 seconds Right leg is in contact with floor for 0.7 second o Right stance time is 0.7 second o Right stance phase % is (0.7/1.2) ^ 100% = 58.3% Right leg is in the air for 0.5 second o Right swing time is 0.5 second o Right swing phase % is (0.5/1.2) ^ 100% = 41.7% With faster walking speed – increase or decrease for each variable Cadence Gait cycle time Stance time Stance phase % Single stance time Single stance % Double stance time Double stance % Swing time Swing phase % With faster walking speed Cadence ↑ Gait cycle time ↓ Stance time ↓ Stance phase % ↓ Single stance time ↓ Single stance % ↓ Double stance time ↓ Double stance % ↓ (decrease more than single stance %) Swing time ↓ Swing phase % ↑  Gait phases – Clinical terminologies Heel Strike Foot Flat Mid Stance Heel Off Toe Off Acceleration Mid Swing Deceleration Stance Phase (60 %) Swing Phase (40 %)  Gait phases - Rancho Los Amigos Terminologies Initial Loading Mid Terminal Pre Early Mid Late Contact Response Stance Stance Swing Swing Swing Swing Stance Phase (60 %) Swing Phase (40 %)  Gait phases – compare clinical vs. RLA terminologies Heel Strike Foot Flat Mid Stance Heel Off Toe Off Acceleration Mid Swing Deceleration Stance Phase (60 %) Swing Phase (40 %) Initial Loading Mid Terminal Pre Initial Mid Terminal Contact Response Stance Stance Swing Swing Swing Swing Right leg is the reference leg for all the following slides IR (Initial contact) and LR (Loading Response) IC (Initial contact) R’t foot contacts the floor Typical contact is by heel strike LR (Loading response) From R’t IC to right before L’t toe-off It is in double-support Transfer weight from L’t to R’t leg L’t leg is unloading, R’t leg is loading Initial Loading R’t foot becomes flat on the ground Contact Response MS (mid-stance) phase MS (Mid-stance) phase From L’t toe-off to Body over R’t foot “Up hill” COM @ highest position Weight continues transferring to R’t leg L’t leg swings forward. It is in swing phase. R’t leg is in single stance Loading Mid Response Stance TSt (Terminal stance) phase TSt (Terminal stance) phase From Body rolls over foot to right before L’t IC “Down hill” COM becomes lower than @ MSt Weight is transferred to R’t foot R’t heel rises L’t leg has not contacted floor yet. L’t leg is in swing phase. R’t leg is still in single stance Mid Terminal Stance Stance PSw (Pre-swing) phase PSw (Pre-swing) phase From L’t IC to right before R’t toe-off Transfer weight from R’t to L’t leg R’t leg is unloading, L’t leg is loading R’t leg has not left the floor yet. And L’t already contacts the floor. So it is double support phase R’t toe off right after PSw ends Terminal Pre Stance Swing *PSw (Pre-swing) phase is part of stance phase Swing phase is divided into 3 shorter phases Pre Inital Mid Terminal Swing Swing Swing Swing ISw (Initial Swing) R’t Toe Off to R’t Max Knee Flex MSw (Mid-Swing) R’t Max Knee Flex to R’t Tibial Vertibal TSw (Terminal Swing) R’t tibial Vertical to R’t IC  Relationship of gait phases b/w two legs Stance Phase (62 %) L’t IC (Swing Phase (38 %) L R 0% 12% 31% 50% 62% 75% 87% 100% R’t IC Gait phase relationship b/w two legs When R’t leg is in PSw, L’t leg is in ? phase When L’t leg is in PSw, R’t leg is in ? phase Double support phase is composed of two parts IC (L) Stance Phase (62 %) (Swing Phase (38 %) L R 0% 12% 50% 62% 100% IC (R) Double support = + = 12% + 12% = 24% One leg in swing, then the other leg is in single stance IC (L) Stance Phase (62 %) (Swing Phase (38 %) L R 0% 12% 50% 62% 100% IC (R) R Single Stance = L Swing = 38% R Swing = L Single Stance = 38%