Motion Analysis Lab Outline Part I: Introduction of motion analysis Basic introduction Research methods in motion analysis Instrumentation Data collection Data analysis Part II : Application Gait analysis Clinical application Sports medicine
Motion Analysis Lab Part I: Introduction of motion analysis Basic introduction Research methods in motion analysis Instrumentation Data collection Data analysis
Motion Analysis Lab Introduction What is motion analysis ? When and why do we need to analyze motion? What knowledge do we need before research?
Motion Analysis Lab Introduction Kinematics ( 運動學） Kinematics is concerned with the geometry of motion and deal with relationships among displacement, velocity, acceleration, and time without any reference to the cause of motion To describe the motions we see
Motion Analysis Lab Introduction Kinetic ( 力動學 ) Kinetics deal with relationships among forces, mass, and motion of the body, it is concerned with the cause of motion To understand why the motions occur force / torque
Motion Analysis Lab Anthropometry ( 人體測量學） Involving body and limb measurements - -mass of segment - -location of mass center - -segment length - -center of rotation - -angle of muscles - -mass and cross-sectional area of muscles - -moment of inertia Introduction
Motion Analysis Lab BM = Total Body Mass; BH = Body Height I = %I*Segment Mass*Segment Length 2 Segment L (%BH) Mass (%BM)Child < 14 y Mass (kg) %L CoM (%BH) (from distal joint) Child < 14y %L CoM (%BH) %I * (in kg.m 2 ) Head *age Torso *age *age50.3 Upper arm *age *age Forearm *age *age Hand Thigh *age *age32.3 Shank *age *age30.2 Foot *age *age47.5
Motion Analysis Lab Introduction Muscle and joint biomechanics Characteristics of muscle and joint - length-tension relationship - force-velocity relationship - joint type
Motion Analysis Lab Introduction Electromyography ( 肌電圖） - the study of muscle electrical activities providing information about the control and execution of voluntary movement
Motion Analysis Lab Steps of motion analysis Setting the purpose Choosing the appropriate instrumentation Data collection Data analysis Results and interpretation
Motion Analysis Lab
Instrument_ kinematics （ Electro) goniometers ( 量角器） - a device for measuring joint angles
Motion Analysis Lab Instrument_ kinematics Accelerometer ( 加速規） - a device that measures acceleration types: strain gauge piezoresistive piezoelectric
Motion Analysis Lab Instrument_ kinematics Imaging system Cinematograph digital video charge-couple device (CCD) cameras: - Motion analysis, VICON, Qualisys system
Motion Analysis Lab
Eagle Digital RealTime System Hz selectable frame rates Passive (retroreflective) markers
Motion Analysis Lab EVa Real-Time Software (EVaRT) 3D Display XYZ Graphs Analog Graphs
Motion Analysis Lab Instrument_ kinetic Force transducers - measure the applied forces types: Piezoresistive Piezoelectric
Motion Analysis Lab Instrumentation_ kinetic Force plate - most commonly used type of force transducer - measuring ground reaction force (GRF) type: Strain gauge Piezoelectric
Motion Analysis Lab Instrumentation_ kinetic Kistler force plate
Motion Analysis Lab Steps of motion analysis Setting the purpose Choosing the instrumentation (kinematics, kinetic, EMG…..) Data collection Data analysis Results and interpretation
Motion Analysis Lab Data collection Calibration - to define the global coordinate system
Motion Analysis Lab Data collection Preparation - measurements of basic data - placement of EMG electrodes - marker attachment on the landmark (marker set) - others
Motion Analysis Lab Data collection Placement of EMG electrodes Others: setting the appropriate mode - sampling rate - collection time - amplify….
Motion Analysis Lab Steps of motion analysis Setting the purpose Choosing the instrumentation (kinematics, kinetic, EMG…..) Data collection Data reduction & analysis Results and interpretation
Motion Analysis Lab Data reduction & analysis Signal output Signal processing - data smoothing - interpolation - filter: low pass, band pass, high pass filter…... - re-sampling Setting the appropriate parameters
Motion Analysis Lab Data analysis Calculation - kinematics Translation and Rotation of different coordinate systems Step 1: compute Step 2: compute Step 3: compute Resolve the joint angles :
Motion Analysis Lab Data analysis Calculation kinetic(ground reaction force, joint moment) Inverse dynamics EMG: Rectified Linear envelope Integrated……..
Motion Analysis Lab Take home message How to choose the appropriate instrument? - according to the research purpose - understanding the pros and cons How to collect data well? - following the manuscript - setting the appropriate mode What should be noticed in data analysis? - avoid distortion after signal processing - understanding the limitation and problems of different computing method What should be noticed while reading the report? - does the result make sense?
TAKE A BREAK
Motion Analysis Lab Part II : Applications Projects in motion analysis laboratory Gait analysis Clinical applications Sports medicine
Motion Analysis Lab Gait analysis Bipedal locomotion, or gait, is a functional task requiring complex interactions and coordination among most of the major joints of the body, particularly of the lower extremity.
Motion Analysis Lab Anatomical considerations_ hip joint flexion-extension occurs about a mediolateral axis. adduction-abduction occurs about an anteroposterior axis. internal-external rotation occurs about a longitudinal axis.
Motion Analysis Lab Anatomical considerations_ knee joint 3 degrees of freedom of angular rotation are also possible during gait. The primary motion is knee flexion-extension. Knee internal-external rotation and adduction- abduction may also occur, but with less consistency and amplitude among healthy individuals owing to soft tissue and bony constraints to these motion.
Motion Analysis Lab Anatomical considerations_ ankle and foot Ankle motion is restricted by the morphological constraints of the talocrural joint, which permits only plantarflexion (extension) and dorsiflexion (flexion). In gait analysis as a rigid segment, the foot is required to act as both a semirigid structure and a rigid structure that permits adequate stability
Motion Analysis Lab Gait Cycle Stance phase:60%, including foot flat, midstance, terminal stance, and pre-swing. Swing phase: 40%, including initial swing, midswing, and terminal swing.
Motion Analysis Lab Time-distance variable Ranges of normal values for time-distance parameters of adult gait at free walking velocity Stride or cycle time1.0 to 1.2 sec Stride or cycle length1.2 to 1.9 m Step length0.56 to 1.1 m Step width7.7 to 9.6 cm cadence90 to 140 step/min velocity0.9 to 1.8 m/sec
Chair-rise in Patients after Total Knee Arthroplasty Fong-Chin Su, Kuo-An Lai, Wei-Hsien Hong Clin Biomech 13: , 1998
Motion Analysis Lab Objectives To understand the biomechanics and compensatory mechanisms of chair-rise in patients after TKA. Functional evaluation of pre-op patients compared to the normal elderly.
Motion Analysis Lab subject N age body height body weight (yr) (cm) (kg) normal elderly OA patient TKA patien t 12 14* 12* ± ± ± ± ± ± ± ± ± 8.00 * : OA patients ( 10 bilateral, 4 unilateral ) TKA patients ( 8 unilateral, 4 bilateral ) Subjects
Motion Analysis Lab Experiment Setup
Motion Analysis Lab Marker Set
Motion Analysis Lab Sit-to-Stand a b c d a - b : flexion momentum phase a - b : flexion momentum phase b - c : momentum transfer phase b - c : momentum transfer phase c - d : extension phase c - d : extension phase * 4 chair heights: 115%, 100%, 80%, 65% knee height
Motion Analysis Lab elderly TKA patient Fh Fk Fa
Motion Analysis Lab elderlyTKA patient COM Joint Moment
Motion Analysis Lab Conclusion TKA patient has larger displacement and horizontal velocity of COM compared to the normal elderly. No significant difference in angles of three joints. TKA patients has special pattern in nearly knee full extension. TKA has larger ankle and hip moments. Increased chair height, decreased joint angles and moments.
Common Abnormal Kinetic Patterns of the Knee in Gait in Cerebral Palsy C.J. Lin, L.Y. Guo, F.C. Su, Y.L. Chou Gait & Posture, 11: , 2000
Motion Analysis Lab Objectives To investigate the detailed kinetic characteristics of each abnormality. 23 children suffering from cerebral palsy with spastic diplegia, were recruited 46 limbs into four groups: jump (n = 7) crouch (n = 8) recurvatum (n = 14) mild (n = 17)
Motion Analysis Lab Crouch Gait Results show that crouch gait usually has larger and long-lasting knee extensor moments at stance. This reveals that rectus femoris has relatively high activation.
Motion Analysis Lab Recurvatum Knee Knee flexor moments are large and long-lasting during stance. The biceps femoris muscle shows less activation in EMG the soft tissue behind the knee joint provides this flexor moment. This may result in worse recurvatum knee due to overstretch by the external forces.
Motion Analysis Lab Aims To employ a computerized motion analysis system to identify the effect of ankle arthrodesis on three-dimensional kinematic and kinetic behaviors of the rear and fore foot and muscle activities of the lower extremity during level walking.
Motion Analysis Lab Subjects Patients: 10 (7 males and 3 females) with single-side solid arthrodesis of the ankle performed due to trauma, degenerative osteoarthritis or rheumatic arthritis, were recruited for this study. The mean age was 39.6 years old (13 to 64 y/o). The mean duration of follow-up after arthrodesis was 1.7 years (0.5 to 4 years). Controls: 10 normal subjects, mean age 28.8 yrs (20 to 35 y/o)
Motion Analysis Lab Markers set & coordinate system x f z f x h x t x f x t x h z t z h y f y t y h
Motion Analysis Lab Experiments
Motion Analysis Lab RANGE OF MOTION
Motion Analysis Lab Hindfoot Motion
Motion Analysis Lab Forefoot Motion
Motion Analysis Lab Ground Reaction Force % Stance Phase % BW F1-T1 F2-T2 F3-T3 Ankle arthrodesis Normal VerticalForce white: no change red: increase green: decrease
Motion Analysis Lab Ground Reaction Force % Stance Phase % BW F4-T4 F5-T5 F6-T6 Fore-aft force Ankle arthrodesis Normal white: no change red: increase green: decrease
Motion Analysis Lab Ground Reaction Force % BW % Stance Phase F7-T7 F8-T8 F9-T9Medial-lateralforce Ankle arthrodesis Normal white: no change red: increase green: decrease
Motion Analysis Lab Pressure distribution in stance phase 12 34
Motion Analysis Lab
Motion Analysis Lab Conclusion - motion Hindfoot No 2nd rocker Increased eversion and external rotation throughout whole gait cycle. Forefoot Increased third rocker motion at toe-off. Increased adduction Significant increased eversion at toe-off.
Motion Analysis Lab Rage of Motion Ankle fusion causes decrease of sagittal movements of hindfoot. increase of transverse movements of hindfoot. increase of forefoot motion in three planes.
Motion Analysis Lab Ground Reaction Force Decreased loading rate. Weak body support in midstance and push- off in preswing. Smaller fore-aft shear force. Greater lateral shear force.
Motion Analysis Lab Force and Pressure in 10 Masks Affected side : pressure and force in rearfoot, forefoot and toe areas lack of the force absorption and forward progression pressure and force in two midfoot areas supposing pronated gait
Biomechanical Evaluation of New Type Stair Climbing Machine (S770)
Motion Analysis Lab Purpose To investigate the biomechanics of new type stair climbing machine (S770). (1) kinematics: - movement range of hip, knee, and ankle joints (2) kinetics: - foot contact force - joint moment (3) muscle activities
Motion Analysis Lab Methods_ subject 12 healthy young adults - 2 females, 10 males - Age: 24.5±1.2 y/o - Body height: 171.1±5.5 cm - Body weight: 64.0±9.6 kg
Motion Analysis Lab Methods_ instrumentation 6-axis load cell:6-axis load cell: - embedded in the left foot pedal Surface EMG system:Surface EMG system: - MA 300 Motion analysis system: - 8 Eagle digital cameras - 15 reflective markers
Methods _ data collection Four conditions: - step to end range, trunk static - step to end range, trunk shift - step at selected range, trunk static - step at selected range, trunk shift Stepping at selected speeds 3 trials/condition, 15 secs/trial
Motion Analysis Lab Animation_ step to end range Trunk static Trunk shift
Motion Analysis Lab Animation_ trunk static Step to end range Step at selected range