2Outline Part I: Introduction of motion analysis Basic introduction Research methods in motion analysisInstrumentationData collectionData analysisPart II : ApplicationGait analysisClinical applicationSports medicine
3Part I: Introduction of motion analysis Basic introductionResearch methods in motion analysisInstrumentationData collectionData analysis
4Introduction What is motion analysis ? When and why do we need to analyze motion?What knowledge do we need before research?
5Introduction 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 seeKinematics: what we see
6Introduction 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
7Introduction Anthropometry (人體測量學） Involving body and limb measurementsmass of segmentlocation of mass centersegment lengthcenter of rotationangle of musclesmass and cross-sectional area of musclesmoment of inertiaImportant For kinetic
8BM = Total Body Mass; BH = Body Height Segment L (%BH)Mass (%BM)Child < 14 y Mass (kg)%LCoM (%BH) (from distal joint)Child < 14y %LCoM (%BH) %I * (in kg.m2)Head9.67.8*age5049.5Torso31.646.84*age*age50.3Upper arm16.42.70.084*age+2.256.4-0.028*age+55.732.2Forearm13.72.30.015*age+1.2550.19*age+56.130.3Hand8.20.629.7Thigh188.8.131.524*age+6.63456.7*age32.3Shank184.108.40.206*age+3.80957*age30.2Foot11.71.40.015*age+1.87*age47.5BM = Total Body Mass; BH = Body HeightI = %I*Segment Mass*Segment Length2
9Introduction Muscle and joint biomechanics Characteristics of muscle and joint- length-tension relationship- force-velocity relationship- joint type
10Introduction Electromyography (肌電圖） - the study of muscle electrical activities providing information about the control and execution of voluntary movement
11Steps of motion analysis Setting the purposeChoosing the appropriate instrumentationData collectionData analysisResults and interpretation
33Take home message How to choose the appropriate instrument? - according to the research purpose- understanding the pros and consHow to collect data well?- following the manuscript- setting the appropriate modeWhat should be noticed in data analysis?- avoid distortion after signal processing- understanding the limitation and problems of different computing methodWhat should be noticed while reading the report?- does the result make sense?
35Part II : Applications Projects in motion analysis laboratory Gait analysisClinical applicationsSports medicine
36Gait analysisBipedal 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.
37Anatomical 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.
38Anatomical 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.
39Anatomical 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
40Gait CycleStance phase:60%, including foot flat, midstance, terminal stance, and pre-swing.Swing phase: 40%, including initial swing, midswing, and terminal swing.
41Time-distance variable Ranges of normal values for time-distance parameters of adult gait at free walking velocityStride or cycle time1.0 to 1.2 secStride or cycle length1.2 to 1.9 mStep length0.56 to 1.1 mStep width7.7 to 9.6 cmcadence90 to 140 step/minvelocity0.9 to 1.8 m/sec
61ConclusionTKA 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.
62Common Abnormal Kinetic Patterns of the Knee in Gait in Cerebral Palsy C.J. Lin, L.Y. Guo, F.C. Su, Y.L. ChouGait & Posture, 11: , 2000
63ObjectivesTo investigate the detailed kinetic characteristics of each abnormality.23 children suffering from cerebral palsy with spastic diplegia, were recruited46 limbs into four groups:jump (n = 7)crouch (n = 8)recurvatum (n = 14)mild (n = 17)
64Crouch GaitResults show that crouch gait usually has larger and long-lasting knee extensor moments at stance.This reveals that rectus femoris has relatively high activation.
65Knee 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.Recurvatum Knee
69AimsTo 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.
70Subjects 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)
82Conclusion - motion Hindfoot No 2nd rocker Increased eversion and external rotation throughout whole gait cycle.ForefootIncreased third rocker motion at toe-off.Increased adductionSignificant increased eversion at toe-off.
83Rage of Motion Ankle fusion causes decrease of sagittal movements of hindfoot.increase of transverse movements of hindfoot.increase of forefoot motion in three planes.
84Ground Reaction Force Decreased loading rate. Weak body support in midstance and push-off in preswing.Smaller fore-aft shear force.Greater lateral shear force.
85Force 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
86Biomechanical Evaluation of New Type Stair Climbing Machine (S770)
87PurposeTo 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
88Methods_ 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
89Methods_ instrumentation 6-axis load cell:- embedded in the left foot pedalSurface EMG system:- MA 300Motion analysis system:- 8 Eagle digital cameras- 15 reflective markers
92Methods _ 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 shiftStepping at selected speeds3 trials/condition, 15 secs/trial* The resistance was consistent
93Animation_ step to end range Trunk staticTrunk shift
94Animation_ trunk static Step to end rangeStep at selected range
95Results_ joint angle PF(+) DF(-) Flex(+) Ext(-) Abd(+) Abd(+) Add(-) Angular displacement change in a cycle.
96Result_ foot contact force Three directions of foot contact force in a cycleBlue line (ML) mediolateral directionGreen line (AP) anteroposterior direction
97Results_ foot contact force Trunk shift > Trunk staticTrunk shiftEnd rangeTrunk shiftSelected rangeTrunk staticEnd rangeTrunk staticSelected rangeStair climbing machine (S770) < walking and normal stair climbing ( > 1 BW)