Presentation on theme: "Lower limb orthotics Jeff Ericksen, MD VCU/MCV Dept. of PM&R."— Presentation transcript:
1 Lower limb orthoticsJeff Ericksen, MDVCU/MCV Dept. of PM&R
2 Goals Gait review Common conditions for orthotics Key muscles, joint mechanicsCommon conditions for orthoticsLower limb orthotic approachExamples
3 Double stance occurs in initial and terminal 10% of stance, thus middle 40% of stance is single limb supportNormal gait = progression of passenger unit through space with stability and minimal energy output.*Keep center of gravity in tightest spiralMost efficient CG path = line, only with wheelsPerry, J Atlas of Orthotics
6 TerminologyGait Cycle: Sequence of events from initial contact of one extremity to the subsequent initial contact on the same side
7 Gait terminologyStride length: Distance from initial contact of one extremity to the subsequent initial contact on the same side (x= 1.41 m)Step length: Distance from initial contact of one extremity to the initial contact on the opposite side (x= 0.7 m)
8 Terminology Cadence: The step rate per minute (x= 113 steps per min) Velocity: The speed at which one walks(x= 82 m/min)
15 ProgressionMostly from forward fall of body mass as it progresses in front of loaded foot, ankle moves into DF with rapid acceleration as heel risesSwing limb generates second progressional force as stance limb goes into single support phase, must occur to prepare for forward fall
18 Energy consumption Acceleration & deceleration needs Swinging mass of leg must be decelerated by eccentric contraction of extensors and counterforce (acceleration) of bodyForward falling body must be decelerated by shock absorption at initial contact = heel strike
19 Eccentric energy consumption is high Pretibial and quadriceps contraction at initial contact with eccentric control of tibial shank in loading phase on stance leg.Results in 8:5 ratio for energy in deceleration or control activity vs. propulsion activity
20 Determinants of gaitFoot, ankle, knee and pelvis contributions to smoothing center of gravity motion to preserve energyInman APMR 67
21 Determinants 1) Pelvic Rotation 2) Pelvic Tilt 3) Lateral pelvic motion4) Knee flexion in midstance5) Knee motion throughout gait cycle6) Foot and ankle motion
22 Determinants Foot & ankle motion Smooths out abrupt changes in accel/decel & direction of body motionKnee contributes alsoConverts CG curve into smooth sine wave < 2 inch amplitudeCG horizontal translation reduced by leg alignmentreduces side to side sway for stability by > 4 inchesPelvic rotation 4 degrees saves 6/16 vertical dropPelvic tilt 5 degrees, saves 3/16 vertical excursionKnee flexion 15 degrees lowers CG 7/16total savings = 1 inch per leg
25 Muscle activity in gait cycle* 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.Muscle activity in gait cycle*
26 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 modelSpine erector mass active on heel strike each side to prevent trunk flexion over pelvis and provide medial/lateral stability.Muscle activity*
27 Energy costs and gait* Lowest = normal +/- 1 SD Forearm crutch use next = amputee with suction socket prostheticnext = amputee with pylonnext = forearm crutch useEnergy costs and gait*Forearm crutch useNormal subjects
28 Joint stability in gait Determined by relationship between muscle support, capsule & ligamentous support, articular relationships and lines of force
35 Leg length difference< 1.5 in, see long side shoulder elevation with dipping on short leg sideCompensation with dropping pelvis on short sideExaggerated hip, knee, ankle flexion on long side> 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* 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.Other orthopedic problems affect gait*Foot equinus gives steppage gait to clear the relatively longer legCalcaneal deformity changes push off and initial contact
38 Gait changes from orthopedic issues Joint instability gives unstable motion and fear, reduced stance phasePain reduces stance typicallySpine pain may reduce gait speed to reduce impact
39 Hemiplegia gaits Extensor synergy allows ambulation Hip & knee extension, hip IR, foot & toe PF and foot inversionDifficulty 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 side3) Decreased knee and hip flexion on swingphase4) Shortened stance phase5) Upper extremity held in flexion andadduction
41 Lower motor neuron gaits Hip extensor weakness gaitTrunk & pelvis posterior after heel strikeGlut medius limppelvis drops if uncompensatedtrunk shift if compensatedHip flexor weaknessLeg swung by trunk rotation pulling leg on hip ligaments
42 Lower motor neuron gaits Keeps line of force behind knee when compensate for gastroc/soleus weakness.Lower motor neuron gaitsQuadricep weakness: forcible extension using hip flexors, heavy heel strike and forward lean over heel to keep force anterior to knee joint.Gastroc/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 Dorsiflexor weakness gives steppage gaitFoot slap in fast walk with mild weakness and if some strength, may be noticable with fatigue as eccentric TA activity failsForefoot = initial contact point if no strength for DF present
46 LE OrthoticsWeaknessSkeletal & joint insufficiency
47 Leg joint alignment orthoses Use with & without weight bearing featuresMost common in knee support for RA induced ligamentous lossForm fitting shells better than bandsAlignment of knee joint is keyTypically use single axis knee joints for these orthoses
49 LE weakness orthoses HKAFO’s AFO’s Reciprocating Gait Orthosis Functional Electrical Stimulation (FES)AFO’sDouble metal uprightPlasticMoldedoff shelfVAPCKAFO’sMany designs for band configurationsMetal vs. plastic
50 AFO’s Most common orthotic Stabilizes ankle in stance Helps clear toe in swingGives some push off in late stance to save energyRemember effects on knee!!
51 AFO’sDouble metal upright allows for anterior and posterior stops and spring assist for DF & PF force generation.Hinged molded AFO can be similarMediolateral stability is good but can be enhanced with T-straps
55 Knee effects of PF stops PF stop helps weak DF & swing clearance but stops PF of foot at heel strike, force line behind knee destabilizes.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.
56 Posterior PF stop should allow adequate toe clearance in swing but not excessive DF to increase knee bending moment at heel strike.
58 Heel adjustments can help knee* Heel cutting or cushioned heel wedge moves point of ground reaction force contact forward and brings force line closer to knee axis of rotation.Heel adjustments can help knee*
59 Effects of DF stopsAnterior DF stop (plus sole plate in shoe) enables push off and propulsion of limb and pelvisNormal forces if DF stop in 5o PFUse for PF weakness, restores step length on opposite side and knee moments normalize.Spring doesn’t helpToo much PF angle gives genu recurvatumStabilizes knee with absent gastroc/soleus eccentric knee extension help in stance
66 Plastic AFO considerations Light weightVariable shoes can effect performanceSkin irritation very real riskContraindicated in diabetic neuropathy or poorly compliant patient with skin checksMinimal help for PF weakness, mostly for DF weaknessCan help with arch support
68 Knee orthoses Commonly used for genu recurvatum Medial/lateral laxity Swedish knee cage3 way knee stabilizerMedial/lateral laxityJoint system with thigh & calf cuffsAxial derotation bracesAxial rotation control plus angular control in sagittal and frontal planes
74 Knee stability via 3 force application Anterior force to stop knee buckling2 posterior counterforces at thigh & 1 at calfShoe level counterforce keeps lower leg from posterior motion in closed chain loading
75 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.
76 HKAFO’s Rarely used, indicated for hip extensor weakness Pelvic band often necessary for stabilization and suspension
77 Hip orthotics for dislocation risks AdultsPediatricsScottish RitePavlik Harness
78 Reciprocation Gait Orthosis Releasable hip joint & knee joint for sittingCable coupling of hip flexion to contralateral hip extension