no slide title · 1. become more familiar with how shoe and afo design alter ankle-foot mechanics...
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Clinical WorkshopThermo Formable
Ankle-Foot Orthoses
1. Become more familiar with how shoe and AFO design alter ankle-foot mechanics during gait
2. Sharpen our ability to observe and analyze the gait and needsof patients
3. Become familiar with application of thermo formable AFO technology
4. Practice using thermos formable technology in AFO fabrication
5. Critique the results for our patients to practice raising our standards
6. Observe, discuss and learn as colleagues
Workshop Goals
• Lectures focusing on mechanics of gait and foot support
• Information about orthotic ankle joint options
Workshop OutlineDAY ONE
• Pediatric and structural considerations
• Patient evaluations andcasting
Workshop OutlineDAY TWO
• Factors impacting patient comfort and function
• Mould rectification (and thermoplastic moulding)
Workshop OutlineDAY THREE
• Thermoplastic moulding
• Complete fabrication
• Fitting to patient
Workshop OutlineDAY FOUR
• Complete fitting andoptimizing AFO’s
• Discuss / critique results
Workshop OutlineDAY FIVE
• Look-back at the week
• General comments on the course (pluses & minuses)
• Certificates
Workshop OutlineDAY SIX
Clinical Biomechanicsof the Foot and Ankle
During Gait(sagittal plane, barefoot)
There IsA Plethora of
Gait DataAvailable
InternalResponse
ExternalForce
Will focus on buildingfamiliarity with a
small number of gait mechanics basics I have
found clinically useful
Stance Phase of Gait (60%)
SagittalPlane
Barefoot
Stance Phase: Initial Contact
Initial Contact to Foot Flat(IC-FF Interval a.k.a. First Rocker)
Foot Flat to Heel-Off(FF-HO Interval a.k.a. Second Rocker)
Heel-Off to Toe-Off (HO-TO Interval a.k.a. Third Rocker)
Swing Phase
How Ankle-FootMechanics Are Altered
By Footwear
Initial Contact
Initial Contact
Consider Consequences of:
• Fused / Rigid Ankle Joint• AFO with Plantarflexion
Stop at 90°• AFO with Rigid Ankle
(During First Rocker)
• On Gait
• On Knee Stability
• On Quadriceps Fatigue
How Can WeCompensate For Loss
of PlantarflexionDuring First Rocker?
• Shoe Heel Modifications
• Orthotic Ankle JointOptions (Dorsi-Assist)
How Can Rshoe Be Decreased?
Second Rocker
• Heel Design Affects Initial Portion of This Interval as Discussed
• Sole Factors AffectLatter Portion Profoundly
Heel-Off to Toe-Off (Third Rocker?
Consider Various Patient Factors:
• Rigid M-P Joints OrPainful Extension
• Ulcers or Tenderness UnderMetatarsal Heads
• Arthritic / Painful Ankle Joint
• Loss of Sensation
Heel-Off to Toe-Off
If Anterior Bar Is Moved 2 cm Forward, What Is Effect on Gait?
Barefoot Mechanics
How DoHeel - Sole Shape
(and Pain)Change
Stride Length?
Interaction ofAFO Design FeaturesAnd Gait Mechanics
AFO Interaction with Gait Mechanics (IC – FF Interval)
If Ankle Is Not Allowed to Plantarflex at
(and just after) I.C., Second Rocker
(Ankle Action) Is DelayedUntil After Mid-stance
AFO Interaction with Gait Mechanics (IC – FF Interval)
What Can We Do to Reduce
Knee Instabilityand Smooth Gait?
(At IC and during IC-FF Interval)
Shoe Considerations…• Cushion or Bevel Heel
AFO Considerations…• Ankle Joint with
Plantarflexion Stop…Same as Rigid Ankle During This Stance Interval
AFO Considerations…Ankle Joint with Plantarflexion Allowed (Dorsiflexion Assist for Swing Phase Toe Clearance)
BUT Not Too Strong to Prevent IC Plantarflexion
AFO Interaction with Gait Mechanics (IC – FF Interval)
Rigid Ankle EffectOn FF–HO Interval
and HO Event
AFO Interaction with Gait Mechanics (Heel-Off)
Stance Phase of Gait (60%)
Length of AFO:
• Becomes Critical in HO–TO Interval
• Longer AFO (More Anterior Trim Line) Delays Heel–Off and Requires More Energy
AFO Interaction with Gait Mechanics (Heel-Off)
AFO with Free(or Assisted)Dorsiflexion:
Second Rocker (Ankle) Available
Foot Flat – Heel Off
Length of AFO:
• Becomes Critical in HO–TO Interval
• Longer AFO (More Anterior Trim Line) Delays Heel–Off and Requires More Energy
Trim Proximal to Metatarsal Heads unless:
• Plantarflexors - High Tone/Spastic• Stance Stability Critical• ‘‘Steppage” Gait• Toes Curl Under
Any Other Aspectsof AFO or Shoe Design
to Discuss?
Any Other QuestionsAbout Relating AFOor Shoe to Certain
Disabilities orImpairments?
Examples of Impaired Gait• Drop Foot / Peroneal Palsy (Ideal AFO?)
• Stroke– Paralysis and Spasticity
– Proprioception?
– Balance
• ‘‘Steppage” Gait
Pediatric Considerations in Orthotic Service
• Deformity Progression• Growth and Replacement
• Bone Strength Considerations
• Mobility & Child Development
• Independence & Development
• Family Factors
Deformity Progression
• Soft Tissue DimensionsChange Very Rapidly(difficult to reverse)
• Osseous Changes Not AsRapid (virtually impossibleto reverse)
Deformity Progression
• Maximize CorrectiveOrthopedic Support
• Take Full Advantageof Flexibility of RemainingGrowth (CP child examplewill be show later)
Growth and Replacement
• Look At Function
• Look At Skin
• Depends on Regular Loading (femur & tibia)
• Twice Per Day Weight Bearing
Bone Strength Considerations
Mobility & Child Development• Early Floor Play
(non-walking mobility)• Standing• Walking• Wheelchair
Early Floor Play
Standing
Independence & Development
Remember: Greater Independence
Develops Self-Confidence*Help child be less
dependent on others
Family Factors
Minimize Family Burden(Consistent with goal
to help child beless dependent)
ThermoplasticMaterials andComponentry
for AFO’s
Why Are ThermoplasticsReplacing Metal?
• Material Strength? NO!• Material Stiffness /
Rigidity? NO!• Fabricatability? YES!
Thermoplastics Can Be Easily Formed
(At Relatively Low Temperatures)
Into Shell Structures
#1 Structural Strength Derived from Bars, Beams, Posts and Columns
#2 Structural StrengthDerived from Outer Shell or ‘‘Skin”
#3 Combination
Design Options
#1 Bars, Beams, Posts and Columns, etc. StructuresMany Material and Fabrication Choices (when weight NOT a factor)
#2 Shell StructuresFewer Material and Fabrication Options, But Can Achieve Much Higher Structural Strength with Less Weight
Choose Shell-Type Structures When:• Need High Strength-to-Weight
Ratio (airplanes, rockets,things that fly)
or…• Need A Complex Contoured
Shape
Thermoplastic Orthoses• Shell – Light Weight• Complex Contours –
Achieve Optimum OrthopedicSupport and Cosmetic Shape
Types of Thermoplastic AFO’s
1. Rigid Ankle2. Flexible ‘‘Posterior Leaf”3. With Ankle Joints
Rigid Ankle AFO
Often ServesPatient
Quite Well
Flexible ‘‘Posterior Leaf” AFO• Also Can Work Quite Well
BUT• Plantarflexion Control Characteristics
Usually Change With Time• Calf Portion ‘‘Pistons”• Durability Questionable
Thermosplastic AFOwith Ankle Joint
Componentry(Choices)
• Free Joint – With or Without Extrinsic Plantarflexion Stop
• Joint With Intrinsic Stop(Selectable or Variable)
• Joint With Motion Assist
Free Joint
Joint With Intrinsic Stop
Joint With Intrinsic Stop
Joint With Motion Assist
DorsiflexionAssist
JointComponentDurability
Rotating Shock Load Test Machine
Gait Simulation Test Machine
Pull Load-Deformation Test Machine
180° Peel Strength Test
Rub Test Machine
Uni-Directional Rub Test Machine
Durability1st Tamarack Flexure Joints
(740 and 742 Series)• Several Million Punishing Load Cycles• Most Durable By Wide Margin
2nd Tamarack ClevisphereCamber Axis
3rd Overlap Metal Strap HingeSome Other Options: Very Little Useage
Taking Plaster Impression• Testing Correctability• How to Best Position Ankle-Foot• Go Through the Motions• Internal Rotation?• Weight-Bearing Simulation – How Much?• Instruct Patient/Helper• Plaster Application
• Correct Direction• Lay It On - Minimal Tension
Principles of Mold Rectification
Good Mold Rectification Begins With A Good Plaster Impression
• Bony Landmarks Accurate and Clear
• Joint Alignments Optimized As Possible
• Partial Weight-Bearing
Invest Time, Thought, Technique
in the Impression to Minimize
Rectification Time
1. Reinforce Landmarkings If/As Necessary
2. Screen/File to Smooth Sock Print, Bulges, etc. (clean-up)
3. Compare Measurements to Form
4. Correct Alignment If/As Necessary
5. Remove Plaster Where Closer Fit Or Orthopedic Support Is to Be Increased
6. Place Nails Where Relief Needed for Bony Prominances
7. Add Plaster Where/As Appropriate
8. Screen/Sand the Surface Blending Contours
9. Verify Measurements
10. Assess Rectified Mold – It Should Look Like Part of A Living Body - Not ‘‘Boxy”
Rectification Steps
Principles of “Shape Matching”
Principles of “Shape Matching”
Cushioning Most Necessary When Bony Area
Is Large
– Skull – Tibial Flare– Shin – Atrophied Area
Consider theRelationship Between
Shape Matching,Cushioning and
Suspension Or Fit
Don’t Forget…
As You Rectify, You May Refer to Your Own Anatomy• Locate A Lost or
Missing Landmark• Estimate A Contour• Etc.
Stance Phase of Gait (60%)
Stance Phase of Gait (60%)