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  1. 1. Lower limb orthoticsJeff Ericksen, MDVCU/MCV Dept. of PM&R
  2. 2. GoalsGait review Key muscles, joint mechanicsCommon conditions for orthoticsLower limb orthotic approachExamples
  3. 3. Normal gait = progression of passenger unit through space with stability and minimal energy output.* Keep center of gravity in tightest spiral Most efficient CG path = line, only with wheels Perry, J Atlas of Orthotics
  4. 4. Initial Loading Mid Terminal Pre- Initial Mid- TerminalContact Response Stance Stance Swing Swing Swing SwingWeight Acceptance Single Limb Support Limb Advancement Stance Phase Swing Phase
  5. 5. TerminologyGait Cycle: Sequence of events frominitial contact of one extremity tothe subsequent initial contact on thesame side
  6. 6. Gait terminologyStride length: Distance from initial contactof one extremity to the subsequent initialcontact on the same side (x= 1.41 m)Step length: Distance from initial contactof one extremity to the initial contact onthe opposite side (x= 0.7 m)
  7. 7. TerminologyCadence: The step rate per minute (x= 113 steps per min)Velocity: The speed at which onewalks (x= 82 m/min)
  8. 8. Normal GaitClassic Gait Terms:1) Heel Strike2) Foot Flat3) Midstance4) Heel Off5) Toe Off6) Initial Swing/ Midswing/ Terminal Swing
  9. 9. Gait EventsPhases:1) Stance Phase: 60%2) Swing Phase: 40%Periods:1) Weight Acceptance2) Single Limb Support3) Limb Advancement
  10. 10. Gait Events (Perry)1. Initial Contact2. Loading Response3. Mid Stance4. Terminal Stance5. Pre-Swing6. Initial Swing7. Mid Swing8. Terminal Swing
  11. 11. ProgressionMostly from forward fall of bodymass as it progresses in front ofloaded foot, ankle moves into DF withrapid acceleration as heel risesSwing limb generates secondprogressional force as stance limbgoes into single support phase, mustoccur to prepare for forward fall
  12. 12. Energy consumptionAcceleration & deceleration needsSwinging mass of leg must bedecelerated by eccentric contractionof extensors and counterforce(acceleration) of bodyForward falling body must bedecelerated by shock absorption atinitial contact = heel strike
  13. 13. Eccentric energy consumption is highPretibial and quadriceps contractionat initial contact with eccentriccontrol of tibial shank in loadingphase on stance leg.Results in 8:5 ratio for energy indeceleration or control activity vs.propulsion activity
  14. 14. Determinants of gaitFoot, ankle, knee and pelviscontributions to smoothing center ofgravity motion to preserve energy Inman APMR 67
  15. 15. Determinants1) Pelvic Rotation2) Pelvic Tilt3) Lateral pelvic motion4) Knee flexion in midstance5) Knee motion throughout gait cycle6) Foot and ankle motion
  16. 16. Determinants Foot & ankle motionPelvic rotation 4 degrees Smooths out abruptsaves 6/16 vertical drop changes in accel/decelPelvic tilt 5 degrees, & direction of bodysaves 3/16 vertical motionexcursion Knee contributes alsoKnee flexion 15 degrees Converts CG curve intolowers CG 7/16 smooth sine wave < 2 inch amplitude total savings = 1 inch CG horizontal translation per leg reduced by leg alignment reduces side to side sway for stability by > 4 inches
  17. 17. Muscle activity in gait cycle*
  18. 18. Muscle activity*
  19. 19. Energy costs and gait* Forearm crutch use Normal subjects
  20. 20. Joint stability in gaitDetermined by relationship betweenmuscle support, capsule & ligamentoussupport, articular relationships andlines of force
  21. 21. Gait deviationsStructural bony issuesJoint/soft tissue changesNeuromuscular functional changes
  22. 22. Leg length difference < 1.5 in, see long side shoulderelevation with dipping on short legside Compensation with dropping pelvis on short side Exaggerated hip, knee, ankle flexion on long side > 1.5 in, different compensation suchas vaulting on short leg, trunk lean toshort side, circumduct long leg
  23. 23. ROM loss or ankylosis willshow proximal compensation with or without velocity changes.
  24. 24. Other orthopedic problems affect gait*Foot equinus gives steppage gait to clearthe relatively longer legCalcaneal deformity changes push off andinitial contact
  25. 25. Gait changes from orthopedic issuesJoint instability gives unstable motionand fear, reduced stance phasePain reduces stance typically Spine pain may reduce gait speed to reduce impact
  26. 26. Hemiplegia gaitsExtensor synergy allows ambulation Hip & knee extension, hip IR, foot & toe PF and foot inversionDifficulty in loading phase or clearingthe “longer” plegic limb gives step-togait.
  27. 27. Hemiplegia1) Asymmetric Gait2) Step length shortened on the plegic side3) Decreased knee and hip flexion on swing phase4) Shortened stance phase5) Upper extremity held in flexion and adduction
  28. 28. Lower motor neuron gaitsHip extensor weakness gait Trunk & pelvis posterior after heel strikeGlut medius limp pelvis drops if uncompensated trunk shift if compensatedHip flexor weakness Leg swung by trunk rotation pulling leg on hip ligaments
  29. 29. Lower motor neuron gaitsQuadricep weakness: forcible extensionusing hip flexors, heavy heel strike andforward lean over heel to keep forceanterior to knee joint.Gastroc/soleus weakness: poor control ofloading phase DF >> compensation is delaywith resulting knee bending moment andmore quad extensor needs. Reducedforward progression of limb with push offinto swing*
  30. 30. Lower motor neuron gaitsDorsiflexor weakness gives steppagegait Foot slap in fast walk with mild weakness and if some strength, may be noticable with fatigue as eccentric TA activity fails Forefoot = initial contact point if no strength for DF present
  31. 31. LE OrthoticsWeaknessSkeletal & joint insufficiency
  32. 32. Leg joint alignment orthosesUse with & without weight bearingfeaturesMost common in knee support for RAinduced ligamentous lossForm fitting shells better than bandsAlignment of knee joint is key Typically use single axis knee joints for these orthoses
  33. 33. LE weakness orthosesAFO’s HKAFO’s Double metal Reciprocating Gait upright Orthosis Plastic Functional Molded Electrical off shelf Stimulation (FES) VAPCKAFO’s Many designs for band configurations Metal vs. plastic
  34. 34. AFO’sMost common orthoticStabilizes ankle in stanceHelps clear toe in swingGives some push off in late stance tosave energyRemember effects on knee!!
  35. 35. AFO’sDouble metal upright allows foranterior and posterior stops andspring assist for DF & PF forcegeneration. Hinged molded AFO can be similarMediolateral stability is good but canbe enhanced with T-straps
  36. 36. Knee effects of PF stopsPF stop helps weak DF & swingclearance but stops PF of foot at heelstrike, force line behind kneedestabilizes. Minimal 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.
  37. 37. Posterior PF stop shouldallow adequate toe clearance in swing but not excessiveDF to increase knee bending moment at heel strike.
  38. 38. Contact & loading phase knee effects of AFO’s
  39. 39. Heel adjustments can help knee*
  40. 40. Effects of DF stopsAnterior DF stop (plus sole plate in shoe)enables push off and propulsion of limband pelvis Normal forces if DF stop in 5o PF Use for PF weakness, restores step length on opposite side and knee moments normalize. Spring doesn’t help Too much PF angle gives genu recurvatum Stabilizes knee with absent gastroc/soleus eccentric knee extension help in stance
  41. 41. Push off knee effects of AFO’s
  42. 42. Single upright orthosesReduces interference withcontralateral orthoses or medialmalleolusNot useful for mediolateral stabilityproblems
  43. 43. Plastic AFO’sSimilar biomechanical analysisTrim lines of posterior verticalcomponent influence ankle rigidity
  44. 44. Plastic AFO components
  45. 45. Plastic AFO considerationsLight weightVariable shoes can effectperformanceSkin irritation very real risk Contraindicated in diabetic neuropathy or poorly compliant patient with skin checksMinimal help for PF weakness, mostlyfor DF weaknessCan help with arch support
  46. 46. VAPC dorsiflexion assist orthosis
  47. 47. Knee orthosesCommonly used for genu recurvatum Swedish knee cage 3 way knee stabilizerMedial/lateral laxity Joint system with thigh & calf cuffsAxial derotation braces Axial rotation control plus angular control in sagittal and frontal planes
  48. 48. Knee extension control
  49. 49. Knee locks
  50. 50. KAFO’s used in SCI, conus or cauda equina injuries T10 is often cutoff level, use swing to gait with locked knees, considerable energy expenditure
  51. 51. Knee stability added whenAFO not able to control knee Continue to utilize rigid foot plate and DF stop to help push off and PF stop to clear toe in swing
  52. 52. Knee stability via 3 force applicationAnterior force to stop knee buckling2 posterior counterforces at thigh &1 at calfShoe level counterforce keeps lowerleg from posterior motion in closedchain loading
  53. 53. HKAFO’sRarely used, indicated for hipextensor weaknessPelvic band often necessary forstabilization and suspension
  54. 54. Hip orthotics for dislocation risks Adults Pediatrics Scottish Rite Pavlik Harness
  55. 55. Reciprocation Gait OrthosisReleasable hip joint & knee joint forsittingCable coupling of hip flexion tocontralateral hip extension
  56. 56. Questions