Presentation on theme: "ALIGNMENT AND FINE TUNING OF AFO’S UTILIZING THE STRATHCLYDE APPROACH AND THE DYNAMIC RESPONSE ANKLE FOOT ORTHOSIS By: Davin Heyd CO."— Presentation transcript:
1 ALIGNMENT AND FINE TUNING OF AFO’S UTILIZING THE STRATHCLYDE APPROACH AND THE DYNAMIC RESPONSE ANKLE FOOT ORTHOSISBy: Davin Heyd CO
2 Our industry is on the advent of a Paradigm shift on a couple of fronts Research proven techniquesObjective outcomes – pay for performance will be reality
3 Our focus has been wrong! Too much attention on achieving 90 degrees at the ankleNot paying attention to the foot biomechanics and their alignmentNot looking at the entire body too much individual segment focusForcing everything!
4 We must re-assess our approach There is not a supporting body of evidence w regards to our historical approach to LE managementIn fact, research show that 90 neutral is actually unstable and detrimental if we are forcing that AlignmentOwen 2008, Webber 1990/91
5 Now!use what the patient has, Align, relax, control, and balance our patient to the floor.This is a completely new approach
6 Structure Modeling until bone maturation infancy-14 years for girls Infancy-16 years for boys“Prevent over-stretching of ligaments.”Deformation of bone modeling
7 StructureEffective stretch to gastroc-soleus complex occurs when subtalar and midtarsal joints “ARE” properly aligned.
8 Structure Interdependent on each other Talus 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
9 Fixed DF angle Caused by tight heel chord Initial ContactFixed DF angle Caused by tight heel chordRigid Lever Arm
10 Forward motion and weight dictates end result Mid-StanceForward motion and weight dictates end resultIn this case:destructive collapse at the midfootCould also see:Knee hyperextensionEarly heel rise and up on toes??
11 Terminal StanceWide stance with abducted forefoot and externally rotated legWhy?Shorten the lever arm to bring the foot throughCOMPENSATION!
12 FORCE NOTHING! Tardieus 1987 Warned against precipitating painful spasm by over stretching the muscle fibers in the coarse of castingExcessive elongation, particularly at high rate, can produce soft tissue strains or complete ruptureDavid S. Butler 1991Nerves become embedded in tonically – recruited muscles so when the muscle is forcefully stretched so is the nerve contributing to the spasms
13 Physical Assessment Determining functional ROM Calcaneal Alignment. Determine Forefoot alignment to attain vertical heelDetermine first Catch / R1
14 OWEN 74 Children independent ambulators in AFOs Prescription tuned on video vector generator gait laboratoryAnkle angle (PF,DF, or Plantar-grade) did not effect end resultAll ended up being tuned to an inclined angle – 8-14ْْAlignment produced stability in both Normal and Pathological gaitCenters knee joint directly over the middle of the footAuthor suggests starting at 10-12ْ
15 OWEN Shank Angle to Floor Defined : 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 = 0ْْ*Angle of the Ankle, it refers to: Plantar Flexion, Dorsiflexion, and Plantar grade
16 PerryControl of the kinematics of the shank (tibia) relative to the vertical is essential in normal gaitOur patients arehere
17 OWEN Gastrocnemius (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 swingAt 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 activelyPassive StretchActive Stretch
18 OWENSetting 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.
19 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.
20 Utilization of Hinged AFO: One or more of the “contraindications” or “conditions making hinged AFOs irrelevant” apply in most children with Neurological conditions, so the use of hinged AFOs is limited - OWEN
21 Contraindications: Tendency to mid foot instability (Webber 1990/1991) Insufficient passive ROM of DF with knee extended (GN length)Risk of excessive DF at mid stance and terminal stance – insufficient control of the shank by calf muscles - (lack of stability and over lengthening of soleus)Too much tone to allow normal stance phase ankle DF-incline of shank during 2nd rocker will not occur to over come this inclination of the shank needs to be increased making the hinge irrelavant
22 Functions other than gait: Squating to play or pick things upStair climbingSitting and standing up from a chairTraditionally felt that SA AFOs prevent these functionsIf the knee joint is aligned over the center of the foot, it is possible to squat and climb stairs with a SAAFO
23 AFO design An AFO should be designed to provide: Optimum cutaneous and propreoceptive input through the foot and ankleEnhance the biomechanics of load bearing joint alignment through the knee and hips during the stance phase of gait, and to therebyOptimize the postural, weight shift, and movement training process(Owen 2008, Butler PB et al 2007, Major 1995)
24 AFO designThe 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 jointsOwen 2008, Bowers et al 2008, Meadows et al 2008, Owen 2005
25 The DRAFO System: Designed around a scientifically proven biomechanical analysis process and functional gait
26 DRAFO SystemThe DRAFO System Mimics gait biomechanics of normal human locomotion –The 3 foot rockers are incorporated into the orthosis2nd rocker achieved by Tibial AlignmentStabilizes and maintains desired alignment without requiring excessive pressurePlantar aspect functions like a prosthetic foot
27 Allows 1st Rocker at heel strike Achieves Stability at Heel Strike Calcaneal WrapLocks in the HindfootAllows 1st Rocker at heel strikeAchieves Stability at Heel StrikeSach heel effectde-acceleratorDe-rotatorPropreoceptor feedback2nd RockerTibial inclination3rd RockerForefoot design:Posting designed to have duel function:Align forefootManipulate terminal stanceAllows for functional 3rd rocker
28 Standing Alignment Alignment of the center of gravity So that the weight line goesthrough the center of the kneeWhich centers over themiddle of the foot provides theOptimum balance alignment forboth “normal and Pathological”GaitStable alignmentUnstable alignment
30 Validation: Outcomes Measures WHY??? How do we know what we are doing really does what we say it is doing?Outcomes MeasuresWHY???Hospital ContractsInsurance ContractsInstitutional MandatesPrevent misconceptionsState/Federal MandatesSPARGMedicareEverybody else is doing it