Double stance occurs in initial and terminal 10% of stance, thus middle 40% of stance is single limb support
Pre-tibial muscles eccentrically slow plantarflexion after heel strike, some action in stance for sub-talar influence and some activity in swing for toe clearance. Gastroc/soleus with peak in push off for CG propulsion but also eccentrically controls shank progression over ankle. Quads peak after heal strike to absorb knee flexion. RF active in late stance with flexed hip and knee to reduce heel rise. Quads also active in early swing to keep lower leg swinging on femur. Hamstrings with 2 peaks around heel strike. Firstin terminal swing to slow forward swing with hip extension and knee flexion action in open chain role. Second is closed chain role with foot contact to extend knee and hip for stability. Variable late peak helps with extension in push off.
Glut medius and minimus give abduction support in initial contact& early stance to reduce pelvic tilt. Adductors peak at initial contact, possibly from hamstring portion of adductor magnus slowing hip flexion & possibly to help with femur internal rotation in closed chain role. Second adductor peak at end of stance may help accelerate the limb forward into swing with muscles aiding hip flexion. Glut max absorbs heel strike shock eccentrically, keeps hip and knee extended. Second peak with push off may help hip and knee extension to propel body on fully extended stance leg. Show gluts as knee extensor in closed chain model Spine erector mass active on heel strike each side to prevent trunk flexion over pelvis and provide medial/lateral stability.
Lowest = normal +/- 1 SD next = amputee with suction socket prosthetic next = amputee with pylon next = forearm crutch use
May see hip OA patients lean over stance leg to reduce glut medius contraction, shoulder dip. May see external rotation of affected leg due to hip effusion.
Keeps line of force behind knee when compensate for gastroc/soleus weakness.
Heel cutting or cushioned heel wedge moves point of ground reaction force contact forward and brings force line closer to knee axis of rotation.
Considerable forces are measured with variable strap configurations which can cause tissue damage in insensate skin. Cyclic ambulation reduces this effect, but must avoid bony prominences and use adequate straps to distribute forces. Shear forces at knee also vary with strap design.
Lower limb orthoticsJeff Ericksen, MDVCU/MCV Dept. of PM&R
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
TerminologyGait Cycle: Sequence of events frominitial contact of one extremity tothe subsequent initial contact on thesame side
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)
TerminologyCadence: The step rate per minute (x= 113 steps per min)Velocity: The speed at which onewalks (x= 82 m/min)
Normal GaitClassic Gait Terms:1) Heel Strike2) Foot Flat3) Midstance4) Heel Off5) Toe Off6) Initial Swing/ Midswing/ Terminal Swing
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
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
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
Determinants of gaitFoot, ankle, knee and pelviscontributions to smoothing center ofgravity motion to preserve energy Inman APMR 67
Determinants1) Pelvic Rotation2) Pelvic Tilt3) Lateral pelvic motion4) Knee flexion in midstance5) Knee motion throughout gait cycle6) Foot and ankle motion
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
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
ROM loss or ankylosis willshow proximal compensation with or without velocity changes.
Other orthopedic problems affect gait*Foot equinus gives steppage gait to clearthe relatively longer legCalcaneal deformity changes push off andinitial contact
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
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.
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
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
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*
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
LE OrthoticsWeaknessSkeletal & joint insufficiency
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
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
AFO’sMost common orthoticStabilizes ankle in stanceHelps clear toe in swingGives some push off in late stance tosave energyRemember effects on knee!!
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
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.
Posterior PF stop shouldallow adequate toe clearance in swing but not excessiveDF to increase knee bending moment at heel strike.
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
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
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
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
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
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
HKAFO’sRarely used, indicated for hipextensor weaknessPelvic band often necessary forstabilization and suspension
Hip orthotics for dislocation risks Adults Pediatrics Scottish Rite Pavlik Harness
Reciprocation Gait OrthosisReleasable hip joint & knee joint forsittingCable coupling of hip flexion tocontralateral hip extension