Ankle-Foot Orthoses (AFOs) ORTHOTIC SYSTEMS Ankle-Foot Orthoses (AFOs)

ORTHOTIC PRINCIPLES Description An Orthosis is an external device with specialized functions that acts upon the musculo-skeletal system. Orthotics is the field of study concerned with the design, fabrication and application of such devices

ORTHOTIC PRINCIPLES Terminology Orthoses are described or referred to by the joints or regions they encompass The major joints (Hip, Knee, Ankle, etc.) are combined in various ways along with the ending Orthosis to designate a particular orthosis Commonly the first letters of the joint names are combined to form acronyms (KAFO, AFO,KO, etc.)

ORTHOTIC PRINCIPLES Functions Substitution and/or enhancement of motor function Control of joint alignment in sagittal and frontal planes Immobilization and protection of affected areas

ORTHOTIC PRINCIPLES 3-point force systems Reduction in unwanted angular rotation Stabilization about a joint, bone or skeletal segment

ORTHOTIC PRINCIPLES 3-point force systems Reduction in unwanted angular rotation Stabilization about a joint, bone or skeletal segment

ORTHOTIC PRINCIPLES Lever systems and rotation Momentum generated by push-off of contralateral limb Forward motion generated by rotation of lever system Heel Lever Toe Lever Center of Gravity (Body Weight) CG Axis of rotation

ORTHOTIC PRINCIPLES Lever systems and rotation Momentum generated by push-off of contralateral limb Forward motion generated by rotation of lever system CG

ORTHOTIC PRINCIPLES Lever systems and rotation Momentum generated by push-off of contralateral limb Forward motion generated by rotation of lever system Axis of rotation

ORTHOTIC PRINCIPLES Lever systems and rotation Momentum generated by push-off of contralateral limb Forward motion generated by rotation of lever system Axis of rotation

ORTHOTIC PRINCIPLES Lever systems and rotation Momentum diminished by resistance of ipsilateral forefoot Backward motion generated by rotation of lever system CG Axis of rotation Center of Gravity (Body Weight)

ORTHOTIC PRINCIPLES Lever systems and rotation Momentum diminished by resistance of ipsilateral forefoot Backward motion generated by rotation of lever system Axis of rotation

ORTHOTIC PRINCIPLES Lever systems and rotation Momentum diminished by resistance of ipsilateral forefoot Backward motion generated by rotation of lever system Axis of rotation

ORTHOTIC SYSTEMS Ankle-Foot Orthoses (AFOs) Indications Substitute for/enhance weak or absent dorsi/plantar flexors Stabilize foot/ankle in coronal and sagittal planes Provide some knee stability in sagittal plane

Ankle-Foot Orthoses (AFOs) Metal Plastic

Metal AFO Indications Wide fluctuaton in edema At-risk foot (absent or diminished sensation w/edema, visual inpairment, etc.)

Metal AFO Uprights Aluminum - lightweight Stainless Steel - strong

Metal AFO Stirrups Solid - stability Split – shoe change

Metal AFO Ankle Joints Free Motion

Metal AFO Ankle Joints Dorsi-flexion Assist

Metal AFO Ankle Joints Double-action

Metal AFO Auxillary Controls Varus/Valgus Control Strap Controls varus or valgus of rearfoot during weight-bearing

Metal AFO Auxillary Controls Laminated Footplate

Metal AFO Auxillary Controls Pre-tibial Shell

Fitting Criteria for Metal AFOs Height Top of calf no less than 1 1/8” below fibular head Width (A) – Calf band is of sufficient width to control tibia in frontal plane yet not cause undue pressure (B) – Uprights follow contours of M&L calf outline with >1/4” clearance from skin (C) – Ankle joints are spaced>3/8” & 1/4” from M&L malleoli, respectively A B C

Metal AFO Considerations If the orthosis is articulated then insure that the orthotic ankle joint axis is aligned with the anatomical ankle joints Plantar and/or dorsiflexion stops should be adjusted equally within medial and lateral ankle joints Uprights should be situated mid-line on M&L sides of lower leg; calf band should be deep enough to allow this If patient supplies own shoes insure that they fit well before attaching orthosis Check skin integrity (esp. at calf band, ankle joints and shoe) after 1/2 hr. of use. If there are no problems resume use, checking every 4 hours for the first few days

Intentionally Blank

Intentionally Blank

Intentionally Blank

Intentionally Blank

Plastic AFOs (PAFOs)

Plastic AFOs (PAFOs) Solid Articulated One-piece with no separate components; rigidity determined by thickness and shape Articulated Incorporates ankle joints and other components to allow controlled ROM

Plastic AFOs (PAFOs) Solid Rigid

Plastic AFOs (PAFOs) Solid Posterior Leafspring (PLS)

Solid PAFOs Thickness Angle Typically between 1/8” & 1/4” Û dorsiflexion = Û knee flexion Û plantarflexion = Û knee extension

Solid PAFOs Material Cross-sectional shape determines rigidity Polyproplyene for strength Co-Polymer for flexibility Cross-sectional shape determines rigidity Flexible Solid

Articulated Plastic AFOs Ankle Joints

Articulated Plastic AFOs Free or limited motion Variable motion

Articulated Plastic AFOs Free or limited motion DF Assist Neutral Tamarack

Articulated Plastic AFOs Free or limited motion Oklahoma

Articulated Plastic AFOs Variable Motion Friddle VM

Articulated Plastic AFOs Variable Motion Camber Angle

Plastic AFOs Auxiliary Components

Plastic AFOs Auxiliary components Posterior ROM Components Plantar Stop Dorsi-Assist

Plastic AFOs Auxiliary components Compcore Reinforces plastic in stress-sensitive areas

Plastic AFOs Auxiliary components Pre-tibial shell Enhances knee extension PTB modifications can reduce weight bearing below

Plastic AFOs Auxiliary components Anterior shell Best for immobilization of foot/ankle

Plastic AFOs Varus/valgus modifications Creates effective 3-point system to control varus/valgus

Plastic AFOs Molded footplate Adds foot control Facilitates use of metal AFO ankle joints

Fitting criteria for Plastic AFOs Trim Lines Around proximal calf area shell is closely contoured Side trim line placement determined by use although a + 3/16” gap between the orthosis and the skin is desirable to accommodate volume fluctuation Along the foot the medial and lateral walls are high enough to control any pronation/supination The medial and lateral distal edges terminate just proximal to the 1st and 5th metatarsal heads, respectively

Fitting criteria for Plastic AFOs Height - Top of AFO is > 1 1/8” below fibula head Width - Proximal calf area is of sufficient width to control tibia in frontal plane yet not cause undue pressure Since heel height influences function of orthosis type of footwear should be determined prior to fabrication Athletic footwear w/removable insoles and velcro straps instead of laces is preferred Patients w/vision and/or sensory impairment require close monitoring to insure skin integrity