Brian Snyder MD/PhD Children s Hospital Harvard Medical School

Transcription

1 Brian Snyder MD/PhD Children s Hospital Harvard Medical School

2 Observe patient s gait pattern as walk into room Systematic musculoskeletal exam (range of motion, joint alignment while standing) Neurologic exam (muscle strength, presence of spasticity or dystonia, movement disorders) Evaluate for pain: Muscle pain or spasm, joint movement, neuropathic, with weight bearing

3 Range of motion across each joint Muscle strength assessment Balance assessment Joint alignment Leg lengths Observational gait assessment

4 Objectively measure temporal parameters (speed, cadence, step length, stride length) Kinematics = linear displacement, angular rotation Sagittal, Coronal and Transverse projections Kinetics = forces and moments generated Dynamic EMG of various muscles

5 Analysis 3D joint motion during gait cycle Linear and angular displacement, velocity and acceleration Range of motion Pattern Timing

6 Force platform embedded in walkway measures ground reaction forces and estimates kinetic components, i.e. force, torque (ground reaction force x distance), and power values applied to the joints

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8 Requires: Generation of mechanical energy muscle motor unit Absorption of mechanical energy eccentric lengthening of muscle: antagonist dampens activity agonist muscle Support to prevent collapse skeletal lever arms Upright posture and balance Clearance in swing

9 Strength = number of fibers in cross-section Excursion = length of fibers Spasticity = dynamic muscle contraction fixed shortening In CP: Decreased cross-section = weak muscle Shortened length = decreased joint range of motion

10 Muscle + ground reaction moments produce joint motion Moment = Force (F) acting perpendicular to rigid lever arm (D): M = F x D Skeleton provides rigid lever arms for muscle forces Joints provide fulcrum or pivot point for movement

11 Stability in stance Clearance in swing Preposition of foot in terminal swing Adequate step length Energy conservation Center of Mass located anterior S2, midway between hips From: Perry J. Gait Analysis: Normal and Pathological Function. Thorofare, NJ: SLACK, Inc.; 1992.

12 Minimizing excursion of center of mass Pelvic motion Coordinated movement knee and ankle Minimizing muscle contraction Position of CM line of action passively flexes / extends joint Ligaments provides passive restraint Momentum inertial motion swing (pendulum) Double joint muscles = transfer of energy between limb segments Storing potential energy in muscles by elongation before contraction or eccentric contraction before concentric contraction Motion in 3 Dimensions MSt single support CM PSw double support

13 Expressed as % to eliminate time, normalize across subjects, initial contact initial contact same limb=100% Stance Phase (60% gait cycle): period during which one (40%) or two feet (DOUBLE STANCE 20%) on the ground Swing Phase (40% gait cycle): period during which limb is advanced forward without foot contacting the ground Relative % of each phase is velocity dependent IC IC 60% gait cycle 40% cycle

14 Right foot heel strike (HS) Followed by left toe off (TO) Left foot heel strike Right foot toe off Ends with right foot heel strike Divided into 8 phases Initial contact (IC) heel strike Loading response (LR) Mid-stance (MST) Terminal Stance (TST) Pre-swing (PSW) toe off Initial swing (ISW) Mid-swing (MSW) Terminal swing (TSW)

15 Step length: distance between IC of alternating limbs (distance between feet during double limb stance Stride length: distance IC IC of same limb (right + left step lengths within a gait cycle)

16 Double Support: period when both feet in contact with ground at same time (2x 10% cycle) occurs 2x: beginning (LR) & end (PSw) of stance phase Single Support: period when only 1 foot in contact with ground = swing period of other limb (40% cycle) Cadence: number of steps per unit time (steps/min) Velocity: horizontal speed of body along plane of progression function of cadence and stride length (cm/sec) LR PSw 10% 10%

17 Numbers indicate start/stop muscle activity% cycle Gluteus Medius controls pelvic tilt during single limb support Iliopsoas advances limb pre- & mid-swing Quadriceps extends early stance, terminal swing Hamstrings eccentrically contract to decelerate swing leg Tibialis Anterior dorsiflexes midand terminal swing, max contraction HS to modulate ankle PF

18 Total ROM = 30 IC LR M/TSt PSw Stance Swing LR = PF (5-6 pf) ISw = continue PF (7 pf - 18 pf) MSt/TSt = DF (6 pf 12 df) MSw = DF to neutral (18 pf - 3 df) PSw = PF (12 df - 7 pf) TSw = minimal PF (2 df - 5 pf)

19 1 st Rocker (IC/LR)= Plantar-flexion eccentric contraction tib ant - controls lowering foot 2 nd Rocker (MSt/TSt) = Dorsi-flexion eccentric contraction GS controls forward motion of tibia/fibula shank over foot 3 rd Rocker (PSw) = Plantar-flexion concentric contraction GS ankle plantar-flexion 1st 2nd 3rd HS Foot flat Heel off

20 Too much plantar-flexion = spastic gastroc/soleus, tight GS/Achilles, weak tibialis anterior Too much dorsi-flexion = weak gastroc/soleus (beware of over-lengthened GS/Achilles) or fixed ankle deformity GS tight GS weak Toe walk Pes plano-valgus recurvatum crouch

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22 ROM = 6 LR PSw Stance Swing LR/MSt/TSt=progressive ER 8-10 ISw/MSw = ER 12 PSw = IR 4 er TSw = IR 4 er

23 Transverse plane: Foot progression angle Distinguish if deviations from hip (fem anteversion), tibia (torsion) or ankle (equino varus, pes plano valgus Coronal Plane: inversion / eversion Excessive varus = activity post stance, ant tibialis and toe swing, weak peroneals Excessive valgus = weakness of inverters or excessive peroneal action, pes planovalgus

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25 Total ROM = 60 IC LR TSt PSw Stance LR = Flex (8-15 fl) MSt/TSt = Ext (15-8 fl) PSw = Flex (8-35 fl) Swing ISw = Flex (35-64 fl) MSw = Ext (64-35 fl) TSw = Ext (35-8 fl)

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27 Erect Posture hamstrings - strong hip extensor, weak knee flexor (short head biceps femorus) Crouched Posture caused by Contracted Psoas + Hamstring Positional lever arm dysfunction Hip lever shortened + Knee lever lengthened = Hamstring better knee flexor and weaker hip extensor Weak Gastroc-Soleus (iatrogenic) eliminates PF/KE couple

28 Erect posture Glut Max + hamstring (30%) Quad (30%) GS (40%) moment arm forefoot generates plantarflexion/knee extension couple by GRF Crouched gait GRF falls behind knee Generates flexion hip and knee Hip and knee extensors continuously active to prevent collapse into flexion GRF front of knee Generates strong extension moment during mid-stance GS Iatrogenic Over-lengthening Gastroc-Soleus eliminates PF/KE Knee

29 Anterior double bump Flexed Flexed Dorsi Flexed

30 Normal gait: Rectus initial swing No muscle mid-swing (pendulum) Hamstring contracts terminal swing CP: rectus + hamstring contract during entire swing phase (damped pendulum) Flexed knee ROM normal

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33 Total ROM = 43 LR MSt Stance Swing LR/MSt/TSt = Ext (35fl -15 ex) PSw = Flex (6 ex - 0 ) ISw/MSw = Flex (0-37 fl) TSw = min Ext (37 fl- 35 fl)

34 Too much flexion = hip flexion contracture, tight iliotibial band, spasticity of hip flexors, pain or hip joint arthrodesis Too little hip flexion = poor active muscle control, weak Glut Max GMx CG Hyperlordosis to get CG behind hip

35 ROM = 13 LR MSt TSt Stance LR/MSt = Add (2-6 ad) TSt/PSw = Abd (6 ad-7 ab) Swing ISw = Abd (4 ab-7 ab) MSw/TSw = Add (7 ab-2 ad)

36 Excessive adduction Trendelenburg gait = weak Glut Medius (2.5x BW), spastic hip adductors, substitution of adductors for weak hip flexor, hip pain (joint force = 3.3x BW) Excessive abduction = hip abduction contracture, circumduction - compensation for actual or effective leg length discrepancy (i.e. foot drop, stiff knee) or weak hip flexors during swing, compensated Trendelenburg

37 ROM = 8 Stance LR = IR 5 MSt/TSt = IR 4 PSw = ER 4 Swing ISw = continue ER 3 MSw/TSw = oscillates ER to neutral

38 Too much internal rotation = femoral anteversion, medial hamstring over activity, adductor over activity, or substitution for weak hip flexors Too much external rotation = over activity TFL, SCFE, circumduction for excessive ankle plantar-flexion

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40 ROM = 4 Stance LR = Post rotation MSt/TSt = Ant rotation PSw = Post rotation Swing ISw = Post rotation MSw = Ant rotation TSw = Post rotation

41 ROM = 8 LR TSt MSw Stance Swing LR = ST limb pelvis rises 4 ISw = ST limb pelvis drops 1 MSt/TSt/PSw = ST limb pelvis MSw/TSw = ST limb pelvis drops 8 rises 8 Neutral Position twice in cycle

42 Neutral position 2x during gait cycle Stance LR/MSt= IR 4 ir TSt/PSw = ER 8 er Swing LR MSt PSw ISw/MSw = gradual IR 4 er TSw = continue IR 4 ir

43 Sagittal plane: Anterior = Proximal Hamstring contracture, hyperlordosis Posterior = Spondylolisthesis Double bump = sym. weak Glut Max spastic psoas, tight Hams Coronal Plane: Pelvic obliquity = scoliosis, hip pathology, circumduction to compensate for real or apparent leg length discrepancy (long) Transverse Plane: Rotation scoliosis, hemiplegia, circumduction gait

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45 Hip Flexion compensations lumbar lordosis, knee flexion to maintain COM over feet for stability (crouched gait) Knee Flexion compensations Concurrent hip flexion to maintain COM over feet toe walking (affected leg relatively shorter), flex contralateral hip & knee (steppage gait) since unaffected limb relatively longer Plantar flexion ankle (equinous) compensations Knee extension thrust (PF-knee extension IC of forefoot with floor flexion hip & knee (steppage gait) since affected limb relatively longer

46 In order to understand gait deviations, it is important to understand the relevance of findings on physical exam. Understanding how to treat the cause of the deviation(s) will help guide therapeutic interventions.