By: Davin Heyd CO

ALIGNMENT AND FINE TUNING OF AFO’S UTILIZING THE STRATHCLYDE APPROACH AND THE DYNAMIC RESPONSE ANKLE FOOT ORTHOSIS

Our industry is on the advent of a Paradigm shift

on a couple of fronts

•Research proven techniquesResearch proven techniques

•Objective outcomes – pay for Objective outcomes – pay for performance will be realityperformance will be reality

Our focus has been wrong!

•Too much attention on achieving 90 degrees at the ankle

•Not paying attention to the foot biomechanics and their alignment

•Not looking at the entire body too much individual segment focus

•Forcing everything!

We must re-assess our approach

•There is not a supporting body of evidence w regards to our historical approach to LE management

In fact, research show that 90 neutral is actually unstable and detrimental if we are forcing that AlignmentOwen 2008, Webber 1990/91

Now!use what the patient has, Align, relax,

control, and balance our patient to the floor.

This is a completely new approach

StructureModeling until bone

maturation infancy-14 years for

girlsInfancy-16 years for

boys

“Prevent over-stretching of ligaments.”

Deformation of bone modeling

Structure

Effective stretch to gastroc-soleus complex occurs when subtalar and midtarsal joints “ARE” properly

aligned.

StructureTalus Alignment : the

alignment of the talus requires effective mechanical base levers.Hindfoot alignment

(stabilize subtalar jt.)Forefoot alignment

(adduct midtarsal jt., supination/pronation)

Interdependent on each other

Initial Contact

Fixed DF angle Caused by tight heel chord

Rigid Lever Arm

Mid-StanceForward motion and weight

dictates end result

In this case:• destructive collapse at the

midfoot

Could also see:•Knee hyperextension•Early heel rise and up on toes

?

?

Terminal Stance

Wide stance with abducted forefoot and externally rotated

leg

Why?

Shorten the lever arm to bring the foot through

COMPENSATION!

FORCE NOTHING!

Tardieus 1987

•Warned against precipitating painful spasm by over stretching the muscle fibers in the coarse of casting•Excessive elongation, particularly at high rate, can produce soft tissue strains or complete rupture

David S. Butler 1991

Nerves become embedded in tonically – recruited muscles so when the muscle is forcefully stretched so is the nerve contributing to the spasms

Physical AssessmentDetermining functional ROM Calcaneal Alignment.

Determine first Catch / R1

Determine Forefoot alignment to attain vertical heel

OWEN

74 Children independent ambulators in AFOsPrescription tuned on video vector generator gait

laboratory

•Ankle angle (PF,DF, or Plantar-grade) did not effect end result

•All ended up being tuned to an inclined angle – 8-14ْْْْ

•Alignment produced stability in both Normal and Pathological gait

•Centers knee joint directly over the middle of the foot

•Author suggests starting at 10-12ْْ

OWEN

Shank Angle to FloorDefined : Angle of the shank (tibia) relative to the horizontal surface when standing in AFOs with heels down and weight equally distributed between heel and toe.

Inclined = if shank is inclined forward from verticalReclined = if shank is reclined from verticalVertical = 0ْْْْ*Angle of the Ankle, it refers to: Plantar Flexion, Dorsiflexion, and Plantar grade

PerryControl of the kinematics of the shank (tibia) relative to the vertical is essential in normal

gait

Our patients are

here

Our patients are

here

OWENGastrocnemius (GN) is a tri-jointed musculotendinous unit (MTU)

crossing the knee, ankle and subtalar joint. It reaches its maximal length twice in the gait cycle (GC):

At initial contact, the knee is extended, the ankle plantigrade, the subtalar joint supinated and the MTU has been lengthening passively during terminal swing

At 40% GC in terminal stance (TST), the knee reaches maximal stance extension, the ankle is in some dorsiflexion, the subtalar joint neutral and the MTU is lengthening actively

Passive Stretch Active Stretch

OWEN

Setting the Angle of the Ankle in the AFO (AA-AFO) without regard to the tri-jointed requirements of the GN can result in insufficient length being available to allow knee extension during the GC. In addition, an overstretched GN in TST will reduce the possibility of MTU force production. The lever arm ratio between the ankle and the knee at 40% GC is 3:2, so small changes in the ankle angle are amplified at the knee.

Owen“The Shank Angle to Floor (SAF) measure of an AFO-Footwear Combination is the prime determinant of gait rather than the AA-AFO.” -An appropriate SAF for normal gait can be achieved with a dorsiflexed, plantigrade or plantarflexed AA-AFO.

-The use of plantarflexion may be essential.

-Using a plantarflexed AA-AFO does not necessarily lead to MTU shortening and may increase MTU length.

Utilization of Hinged AFO:

One or more of the “contraindications” or One or more of the “contraindications” or “conditions making hinged AFOs “conditions making hinged AFOs irrelevant” apply in most children with irrelevant” apply in most children with Neurological conditions, so the use of Neurological conditions, so the use of hinged AFOs is limited - OWENhinged AFOs is limited - OWEN

Contraindications:

• Tendency to mid foot instability (Webber 1990/1991)Tendency to mid foot instability (Webber 1990/1991)

• Insufficient passive ROM of DF with knee extended (GN length)Insufficient passive ROM of DF with knee extended (GN length)

• Risk of excessive DF at mid stance and terminal stance – insufficient Risk of excessive DF at mid stance and terminal stance – insufficient control of the shank by calf muscles - (lack of stability and over control of the shank by calf muscles - (lack of stability and over lengthening of soleus)lengthening of soleus)

• Too much tone to allow normal stance phase ankle DF-incline of shank Too much tone to allow normal stance phase ankle DF-incline of shank during 2during 2ndnd rocker will not occur to over come this inclination of the shank rocker will not occur to over come this inclination of the shank needs to be increased making the hinge irrelavantneeds to be increased making the hinge irrelavant

• Squating to play or pick things up• Stair climbing• Sitting and standing up from a

chairTraditionally felt that SA AFOs

prevent these functions• If the knee joint is aligned over

the center of the foot, it is possible to squat and climb stairs with a SAAFO

Functions other than gait:Functions other than gait:

AFO design

An AFO should be designed to provide:

•Optimum cutaneous and propreoceptive input through the foot and ankle •Enhance the biomechanics of load bearing joint alignment through the knee and hips during the stance phase of gait, and to thereby •Optimize the postural, weight shift, and movement training process

(Owen 2008, Butler PB et al 2007, Major 1995)

The key is to not force alignment, and in the case of an equinous deformity, involves acknowledging and accommodating gastrocnemius hypoextensibility in the AFO and posting the AFO and or shoe as needed to influence the alignment and motion of the load bearing segments in order to optimize the GRF and internal moments at the knee and hip joints

AFO design

Owen 2008, Bowers et al 2008, Meadows et al 2008, Owen 2005

The DRAFO System:Designed around a scientifically proven biomechanical analysis

process and functional gait

DRAFO System•The DRAFO System Mimics gait biomechanics of normal human locomotion –

•The 3 foot rockers are incorporated into the orthosis

•2nd rocker achieved by Tibial Alignment

•Stabilizes and maintains desired alignment without requiring excessive pressure

•Plantar aspect functions like a prosthetic foot

3rd Rocker

Forefoot design: Posting designed to have duel

function:

1. Align forefoot

2. Manipulate terminal stance

Allows for functional 3rd rocker

1st Rocker

Calcaneal Wrap Locks in the Hindfoot

Allows 1st Rocker at heel strike

Achieves Stability at Heel Strike Sach heel effect

de-accelerator

De-rotator

Propreoceptor feedback

2nd Rocker

• Tibial inclination

Standing AlignmentStanding Alignment

Alignment of the center of gravitySo that the weight line goes through the center of the kneeWhich centers over the middle of the foot provides the Optimum balance alignment for both “normal and Pathological”Gait

Stable alignment Unstable alignment

Validation:How do we know what we are doing really does what we say it is doing?

Outcomes Measures

WHY???WHY??? Hospital ContractsHospital Contracts Insurance ContractsInsurance Contracts Institutional MandatesInstitutional Mandates

Prevent misconceptionsPrevent misconceptions State/Federal MandatesState/Federal Mandates

SPARGSPARG MedicareMedicare

Everybody else is doing itEverybody else is doing it

Practical Outcome Measures

7 measures 10MWT 6mWT (2mWT)w Heart rate Standing stability (ABC) Pediatric Balance test AOS Dynamic gait index

Time required maximum of 15 minutes

Items needed Stop watch, tape measure, tape

Validation for: Patient, Practitioner, and Reimbursement Resources