Introduction to Gait Analysis PDF

Introduction to Gait Analysis http://www.brightmindcenter.com/wp-content/uploads/blog-gait-650x429.jpg  Objectives Describe the purposes of the gait assessment Define terms used to describe normal gait cycle Identify the phases of gait Describe basic kinematic variables...

Introduction to Gait Analysis http://www.brightmindcenter.com/wp-content/uploads/blog-gait-650x429.jpg  Objectives Describe the purposes of the gait assessment Define terms used to describe normal gait cycle Identify the phases of gait Describe basic kinematic variables examined during gait Identify & describe major muscles/groups active during gait cycle  Gait Assessment Ranges from very simple (observation) to very complex (lab setting) – Qualitative or quantitative – Often determined by equipment availability Goal is to identify: – Effectiveness and efficiency of walking – Possible impairments limiting ambulation – Safety and balance – Guide interventions Understanding normal gait characteristics can assist with identifying typical gait dysfunctions associated with specific mechanisms Postural Assessment Gait assessment begins with static postural assessment  The Gait Cycle/Stride: Spatial Descriptors Step: heel strike of one foot to heel strike of the other foot Stride: From heel strike of one foot to heel strike of that same foot – Stride: synonymous with gait cycle Stride length – distance from heel to same heel Step length – distance from one heel strike to the to the opposite extremity Step width – distance between heels Spatial Descriptors of Gait  Gait Cycle: Temporal Descriptors Cadence: number of steps per minute –Usual Walking: 110-120 steps/min Extremely high variability –Running: 170-180 steps/min Step time: time for right or left step Stride time: time for 1 full gait cycle/stride https://images-na.ssl-images-amazon.com/images/I/41R4ClcP3nL._SY355_.jpg  Spatial-Temporal Descriptor Walking speed: distance over time (m/s) or (mph) Avg: 1.37m/sec (3mph) –10m walk test –6-min walk test –“self-selected pace” –Fast pace –Pre-determined pace  Normal Value Considerations Age – With increase in age, gait speed decreases, but cadence increases. Why? How might that lead to an intervention? When does it matter?  Stance and Swing in Walking During 1 gait cycle: –Stance = ~60% –Swing = ~40%  Ranchos Los Amigos Terminology (periods of gait cycle) Stance Phase Swing Phase – Initial Contact (IC) Initial Swing – Loading Response Midswing (LR) Terminal Swing – Midstance – Terminal Stance https://www.youtube.com/watch?v=5 mDbF1zHHjw – Preswing https://news.stanford.edu/news/2014/april/images/13763-walking_news.jpg  Initial Contact (IC) 0% gait cycle Instant the foot touches the floor Immediate reaction to body weight transfer 1. Begins stance phase 2. Impact deceleration  Loading Response (LR) 0-10% gait cycle Initial double limb stance period Continues from IC until contralateral foot lifted for swing 1. Shock absorption 2. Weight bearing stability 3. Preservation of progression  Mid-Stance 10-30% gait cycle First ½ of SLS interval Begins when contra limb leaves ground and continues until body weight is over forefoot 1. Progression over stationary foot 2. Limb and trunk stability  Terminal Stance 30-50% gait cycle Completes SLS Begins with heel rise and continues until contra limb has IC. Body weight moves ahead of the forefoot 1. Progression of the body beyond the supporting foot 2. Limb and trunk stability  Pre-Swing 50-60% gait cycle Final phase of stance, second double limb stance interval Begins with IC of contralateral limb and ends with ipsilateral toe off “Weight release” or “Weight transfer” Muscle activated for progression 1. Positions the limb for swing 2. Accelerate progression  Initial Swing 60-73% gait cycle ~ 1/3 of swing period Begins when foot is lifted off surface and ends when swing foot is opposite stance foot 1. Foot clearance 2. Advancement of limb from trailing position  Mid-Swing 73-87% gait cycle Middle 1/3 of swing Begins when swing foot is opposite contra foot, ends when swing limb is fwd and tibia is vertical 1. Limb advancement 2. Foot clearance  Terminal Swing 87-100% gait cycle Begins with vertical tibia and ends with IC Limb advancement completed, leg/shank moves ahead of thigh 1. Complete limb advancement 2. Prepare limb for stance  Displacement of Center of Mass Normal Values 5 cm vertical 4 cm medial-lateral The two peaks of CoM displacement occur together at ~30% and ~80 of gait cycle Mid stance for left and right  Joint Kinematics: gait analysis Sagittal Plane Frontal Plane Horizontal Plane Head Arm Trunk Pelvis Hip Knee Foot https://www.youtube.com/watch?v=Q AnEhz6Eqn4 Bottom-Up or Top-Down  Sagittal Plane Kinematics Total Arc of Segment Motion Motion Anterior and Pelvis 2-4 degrees posterior tilt Flexion and Hip ~ 40 degrees extension Flexion and Knee ~ 60 degrees extension Dorsiflexion and Ankle (TC) ~ 30 degrees plantarflexion Sagittal Plane Kinematics  Frontal Plane Mechanics Total Arc of Segment Motion Motion Up and down Pelvis obliquity 6-8 degrees (abd/adduction) Abduction and Hip ~ 10 degrees adduction Abduction Knee (valgus) and ~ 5 degrees adduction (varus) Inversion and Ankle (STJ) ~ 8 degrees eversion Frontal Plane Kinematics  Horizontal Plane Kinematics Total Arc of Segment Motion Motion Anterior/Posterior Pelvis rotation ~ 6-8 degrees (forw/back) Internal and Hip ~ 15 degrees external rotation Internal and Knee ~ 10 degrees external rotation Ankle negligible n/a Horizontal Plane Kinematics  Summary of Horizontal Plane Kinematics Direction of motion, not absolute joint position During 1st half of stance –Pelvis, femur, tibia IR –STJ everting, MTJ increasing pliability During 2nd half of stance –Pelvis, femur, tibia ER –STJ inverting, MTJ increasing stability During swing –Pelvis, femur, tibia IR –STJ everting, MTJ increasing pliability  Muscle Activity during Walking Most muscles have 1-2 short bursts (100- 400 ms) for ~ 10-40% of gait cycle Gait deviations can be better understood and treated when the clinician understands muscle function during ambulation –Will go into specifics in Movement Science II –But to give you a sense of how important understanding the contracting muscles… Hip Extensors Types of Quantitative Gait Analysis  Gait Rite System 14 Foot long assessment mat with over 16,000 sensors  Plantar Pressure Tekskan or Novel, Pedar System  3D Coordinate System Optical based system where markers are added to limbs and joints Multiple force plates Marker Placement  Pediatric Gait Analysis Children’s Hospital, Zurich Switzerland Royal Children’s Children’s Memorial Hospital, Melbourne AUS Hospital, Chicago IL  Electromyography Tells when muscle is active or in-active Surface or fine-wire (in- dwelling) –Small wire inserted with a small gauge needle  Common Pathological Mechanisms of Gait 1. Structural Deformity 2. Muscle Weakness 3. Sensory Loss 4. Pain 5. Impaired Muscle Performance  Recommendations Identify the REFERENCE limb – When speaking about gait, need to specify which limb Observe someone walk a LOT (not just down and back) – In lab someone may need to walk for 5-10mins – In clinic, you maybe have ~30sec to get an accurate assessment  so practice now! Systematically approach the gait assessment – Top-down or Down-Up Understand and appreciate each phase of the gait cycle and know when one phase stops and one phase starts – Observe for these markers