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%)