1. Lower limb orthotics
Jeff Ericksen, MD
VCU/MCV Dept. of PM&R

2. Goals Gait review Common conditions for orthotics
Key muscles, joint mechanics
Common conditions for orthotics
Lower limb orthotic approach
Examples

3. Double stance occurs in initial and terminal 10% of stance, thus middle 40% of stance is single limb support
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

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

7. Gait terminology
Stride 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)

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 Phases: 1) Stance Phase: 60% 2) Swing Phase: 40% Periods:
1) Weight Acceptance
2) Single Limb Support
3) Limb Advancement

11. Gait Events (Perry) Initial Contact Loading Response Mid Stance
Terminal Stance
Pre-Swing
Initial Swing
Mid Swing
Terminal Swing

15. Progression
Mostly from forward fall of body mass as it progresses in front of loaded foot, ankle moves into DF with rapid acceleration as heel rises
Swing 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 body
Forward 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 gait
Foot, ankle, knee and pelvis contributions to smoothing center of gravity motion to preserve energy
Inman 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 Foot & ankle motion
Smooths out abrupt changes in accel/decel & direction of body motion
Knee contributes also
Converts CG curve into smooth sine wave < 2 inch amplitude
CG horizontal translation reduced by leg alignment
reduces side to side sway for stability by > 4 inches
Pelvic rotation 4 degrees saves 6/16 vertical drop
Pelvic tilt 5 degrees, saves 3/16 vertical excursion
Knee flexion 15 degrees lowers CG 7/16
total 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 model
Spine 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 prosthetic
next = amputee with pylon
next = forearm crutch use
Energy costs and gait*
Forearm crutch use
Normal subjects

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

34. Gait deviations Structural bony issues Joint/soft tissue changes
Neuromuscular functional changes

35. Leg length difference
< 1.5 in, see long side shoulder elevation with dipping on short leg side
Compensation with dropping pelvis on short side
Exaggerated 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 leg
Calcaneal deformity changes push off and initial contact

38. Gait changes from orthopedic issues
Joint instability gives unstable motion and fear, reduced stance phase
Pain reduces stance typically
Spine 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 inversion
Difficulty 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
Hip extensor weakness gait
Trunk & pelvis posterior after heel strike
Glut medius limp
pelvis drops if uncompensated
trunk shift if compensated
Hip flexor weakness
Leg 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 gaits
Quadricep 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 gait
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

46. LE Orthotics
Weakness
Skeletal & joint insufficiency

47. Leg joint alignment orthoses
Use with & without weight bearing features
Most common in knee support for RA induced ligamentous loss
Form fitting shells better than bands
Alignment of knee joint is key
Typically use single axis knee joints for these orthoses

49. LE weakness orthoses HKAFO’s AFO’s Reciprocating Gait Orthosis
Functional Electrical Stimulation (FES)
AFO’s
Double metal upright
Plastic
Molded
off shelf
VAPC
KAFO’s
Many designs for band configurations
Metal vs. plastic

50. AFO’s Most common orthotic Stabilizes ankle in stance
Helps clear toe in swing
Gives some push off in late stance to save energy
Remember effects on knee!!

51. AFO’s
Double metal upright allows for anterior and posterior stops and spring assist for DF & PF force generation.
Hinged molded AFO can be similar
Mediolateral 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.

57. Contact & loading phase knee effects of AFO’s

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 stops
Anterior DF stop (plus sole plate in shoe) enables push off and propulsion of limb and 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

61. Push off knee effects of AFO’s

62. Single upright orthoses
Reduces interference with contralateral orthoses or medial malleolus
Not useful for mediolateral stability problems

64. Plastic AFO’s Similar biomechanical analysis
Trim lines of posterior vertical component influence ankle rigidity

65. Plastic AFO components

66. Plastic AFO considerations
Light weight
Variable shoes can effect performance
Skin irritation very real risk
Contraindicated in diabetic neuropathy or poorly compliant patient with skin checks
Minimal help for PF weakness, mostly for DF weakness
Can help with arch support

67. VAPC dorsiflexion assist orthosis

68. Knee orthoses Commonly used for genu recurvatum Medial/lateral laxity
Swedish knee cage
3 way knee stabilizer
Medial/lateral laxity
Joint system with thigh & calf cuffs
Axial derotation braces
Axial rotation control plus angular control in sagittal and frontal planes

69. Knee extension control

70. Knee locks

71. 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

72. Knee stability added when AFO 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

74. Knee stability via 3 force application
Anterior force to stop knee buckling
2 posterior counterforces at thigh & 1 at calf
Shoe 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
Adults
Pediatrics
Scottish Rite
Pavlik Harness

78. Reciprocation Gait Orthosis
Releasable hip joint & knee joint for sitting
Cable coupling of hip flexion to contralateral hip extension

80. Questions