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
Terminology iGait Cycle: Sequence of events from initial contact of one extremity to the subsequent initial contact on the same side
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)
Terminology iCadence: The step rate per minute (x= 113 steps per min) iVelocity: The speed at which one walks (x= 82 m/min)
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
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
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
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
Determinants of gait iFoot, ankle, knee and pelvis contributions to smoothing center of gravity motion to preserve energy ÝInman APMR 67
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
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
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
ROM loss or ankylosis will show proximal compensation with or without velocity changes.
Other orthopedic problems affect gait* iFoot equinus gives steppage gait to clear the relatively longer leg iCalcaneal deformity changes push off and initial contact
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
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.
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
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
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*
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
LE Orthotics iWeakness iSkeletal & joint insufficiency
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
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)
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!!
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
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.
Posterior PF stop should allow adequate toe clearance in swing but not excessive DF to increase knee bending moment at heel strike.
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
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
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
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