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Lower limb orthotics iJeff Ericksen, MD iVCU/MCV Dept. of PM&R.

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Presentation on theme: "Lower limb orthotics iJeff Ericksen, MD iVCU/MCV Dept. of PM&R."— Presentation transcript:

1 Lower limb orthotics iJeff Ericksen, MD iVCU/MCV Dept. of PM&R

2 Goals iGait review ÝKey muscles, joint mechanics iCommon conditions for orthotics iLower limb orthotic approach iExamples

3 Normal gait = progression of passenger unit through space with stability and minimal energy output.* iKeep center of gravity in tightest spiral ÝMost efficient CG path = line, only with wheels uPerry, J Atlas of Orthotics

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6 Terminology iGait Cycle: Sequence of events from initial contact of one extremity to the subsequent initial contact on the same side

7 Gait terminology iStride length: Distance from initial contact of one extremity to the subsequent initial contact on the same side (x= 1.41 m) iStep length: Distance from initial contact of one extremity to the initial contact on the opposite side (x= 0.7 m)

8 Terminology iCadence: The step rate per minute (x= 113 steps per min) iVelocity: The speed at which one walks (x= 82 m/min)

9 Normal Gait Classic Gait Terms: 1) Heel Strike 2) Foot Flat 3) Midstance 4) Heel Off 5) Toe Off 6) Initial Swing/ Midswing/ Terminal Swing

10 Gait Events iPhases: 1) Stance Phase: 60% 2) Swing Phase: 40% iPeriods: 1) Weight Acceptance 2) Single Limb Support 3) Limb Advancement

11 Gait Events (Perry) 1. Initial Contact 2. Loading Response 3. Mid Stance 4. Terminal Stance 5. Pre-Swing 6. Initial Swing 7. Mid Swing 8. Terminal Swing

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15 Progression iMostly from forward fall of body mass as it progresses in front of loaded foot, ankle moves into DF with rapid acceleration as heel rises iSwing limb generates second progressional force as stance limb goes into single support phase, must occur to prepare for forward fall

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18 Energy consumption iAcceleration & deceleration needs iSwinging mass of leg must be decelerated by eccentric contraction of extensors and counterforce (acceleration) of body iForward falling body must be decelerated by shock absorption at initial contact = heel strike

19 Eccentric energy consumption is high iPretibial and quadriceps contraction at initial contact with eccentric control of tibial shank in loading phase on stance leg. iResults in 8:5 ratio for energy in deceleration or control activity vs. propulsion activity

20 Determinants of gait iFoot, ankle, knee and pelvis contributions to smoothing center of gravity motion to preserve energy ÝInman APMR 67

21 Determinants 1) Pelvic Rotation 2) Pelvic Tilt 3) Lateral pelvic motion 4) Knee flexion in midstance 5) Knee motion throughout gait cycle 6) Foot and ankle motion

22 Determinants iPelvic rotation 4 degrees saves 6/16 vertical drop iPelvic tilt 5 degrees, saves 3/16 vertical excursion iKnee flexion 15 degrees lowers CG 7/16 Ýtotal savings = 1 inch per leg iFoot & ankle motion ÝSmooths out abrupt changes in accel/decel & direction of body motion uKnee contributes also ÝConverts CG curve into smooth sine wave < 2 inch amplitude iCG horizontal translation reduced by leg alignment Ýreduces side to side sway for stability by > 4 inches

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25 Muscle activity in gait cycle*

26 Muscle activity*

27 Energy costs and gait* Forearm crutch use Normal subjects

28 Joint stability in gait iDetermined by relationship between muscle support, capsule & ligamentous support, articular relationships and lines of force

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34 Gait deviations iStructural bony issues iJoint/soft tissue changes iNeuromuscular functional changes

35 Leg length difference i < 1.5 in, see long side shoulder elevation with dipping on short leg side ÝCompensation with dropping pelvis on short side ÝExaggerated hip, knee, ankle flexion on long side i > 1.5 in, different compensation such as vaulting on short leg, trunk lean to short side, circumduct long leg

36 ROM loss or ankylosis will show proximal compensation with or without velocity changes.

37 Other orthopedic problems affect gait* iFoot equinus gives steppage gait to clear the relatively longer leg iCalcaneal deformity changes push off and initial contact

38 Gait changes from orthopedic issues iJoint instability gives unstable motion and fear, reduced stance phase iPain reduces stance typically ÝSpine pain may reduce gait speed to reduce impact

39 Hemiplegia gaits iExtensor synergy allows ambulation ÝHip & knee extension, hip IR, foot & toe PF and foot inversion iDifficulty in loading phase or clearing the longer plegic limb gives step-to gait.

40 Hemiplegia 1) Asymmetric Gait 2) Step length shortened on the plegic side 3) Decreased knee and hip flexion on swing phase 4) Shortened stance phase 5) Upper extremity held in flexion and adduction

41 Lower motor neuron gaits iHip extensor weakness gait ÝTrunk & pelvis posterior after heel strike iGlut medius limp Ýpelvis drops if uncompensated Ýtrunk shift if compensated iHip flexor weakness ÝLeg swung by trunk rotation pulling leg on hip ligaments

42 Lower motor neuron gaits iQuadricep weakness: forcible extension using hip flexors, heavy heel strike and forward lean over heel to keep force anterior to knee joint. iGastroc/soleus weakness: poor control of loading phase DF >> compensation is delay with resulting knee bending moment and more quad extensor needs. Reduced forward progression of limb with push off into swing*

43 Lower motor neuron gaits iDorsiflexor weakness gives steppage gait ÝFoot slap in fast walk with mild weakness and if some strength, may be noticable with fatigue as eccentric TA activity fails ÝForefoot = initial contact point if no strength for DF present

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46 LE Orthotics iWeakness iSkeletal & joint insufficiency

47 Leg joint alignment orthoses iUse with & without weight bearing features iMost common in knee support for RA induced ligamentous loss iForm fitting shells better than bands iAlignment of knee joint is key ÝTypically use single axis knee joints for these orthoses

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49 LE weakness orthoses iAFOs ÝDouble metal upright ÝPlastic uMolded uoff shelf ÝVAPC iKAFOs ÝMany designs for band configurations ÝMetal vs. plastic iHKAFOs iReciprocating Gait Orthosis iFunctional Electrical Stimulation (FES)

50 AFOs iMost common orthotic iStabilizes ankle in stance iHelps clear toe in swing iGives some push off in late stance to save energy iRemember effects on knee!!

51 AFOs iDouble metal upright allows for anterior and posterior stops and spring assist for DF & PF force generation. ÝHinged molded AFO can be similar iMediolateral stability is good but can be enhanced with T-straps

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55 Knee effects of PF stops iPF stop helps weak DF & swing clearance but stops PF of foot at heel strike, force line behind knee destabilizes. ÝMinimal PF stop or just spring assist to pick toe up in swing should be used for flaccid paralysis and only few degrees of DF position for PF stop in spastic paralysis.

56 Posterior PF stop should allow adequate toe clearance in swing but not excessive DF to increase knee bending moment at heel strike.

57 Contact & loading phase knee effects of AFOs

58 Heel adjustments can help knee*

59 Effects of DF stops iAnterior DF stop (plus sole plate in shoe) enables push off and propulsion of limb and pelvis ÝNormal forces if DF stop in 5 o PF ÝUse for PF weakness, restores step length on opposite side and knee moments normalize. ÝSpring doesnt help ÝToo much PF angle gives genu recurvatum ÝStabilizes knee with absent gastroc/soleus eccentric knee extension help in stance

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61 Push off knee effects of AFOs

62 Single upright orthoses iReduces interference with contralateral orthoses or medial malleolus iNot useful for mediolateral stability problems

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64 Plastic AFOs iSimilar biomechanical analysis iTrim lines of posterior vertical component influence ankle rigidity

65 Plastic AFO components

66 Plastic AFO considerations iLight weight iVariable shoes can effect performance iSkin irritation very real risk ÝContraindicated in diabetic neuropathy or poorly compliant patient with skin checks iMinimal help for PF weakness, mostly for DF weakness iCan help with arch support

67 VAPC dorsiflexion assist orthosis

68 Knee orthoses iCommonly used for genu recurvatum ÝSwedish knee cage Ý3 way knee stabilizer iMedial/lateral laxity ÝJoint system with thigh & calf cuffs iAxial derotation braces ÝAxial rotation control plus angular control in sagittal and frontal planes

69 Knee extension control

70 Knee locks

71 KAFOs used in SCI, conus or cauda equina injuries iT10 is often cutoff level, use swing to gait with locked knees, considerable energy expenditure

72 Knee stability added when AFO not able to control knee iContinue to utilize rigid foot plate and DF stop to help push off and PF stop to clear toe in swing

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74 Knee stability via 3 force application iAnterior force to stop knee buckling i2 posterior counterforces at thigh & 1 at calf iShoe level counterforce keeps lower leg from posterior motion in closed chain loading

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76 HKAFOs iRarely used, indicated for hip extensor weakness iPelvic band often necessary for stabilization and suspension

77 Hip orthotics for dislocation risks iAdults iPediatrics ÝScottish Rite ÝPavlik Harness

78 Reciprocation Gait Orthosis iReleasable hip joint & knee joint for sitting iCable coupling of hip flexion to contralateral hip extension

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80 Questions


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