Ankle Orthoses 2 Flashcards
Types of AFO designs
Conventional
Thermoplastic
Floor Reaction
Anterior Shell & PTB
Rigidity of thermoplastic AFO is influenced by a variety of factors
Type of plastic
Thickness of plastic
Trimlines
- Anterior to malleoli results in increased A-P and M-L rigidity
- Posterior to malleoli - Posterior leaf spring design, flexible at the ankle with somewhat of a dorsiflexion spring assist, does not maintain stability of hte ankle
Corrugations vacuum formed in place- carbon fiber inserts or rope modifications
Advantages of Conventional AFO
Dorsi/plantarflexion ROM easily adjusted
Limited skin contact
Edema accomodated
Permanent shoe attachment = compliance when wearing shoe
Disadvantages of Conventional AFO
Heavy
Shoes not easily changed
Cosmetics
Mediolateral control of ankle/foot not as good as in thermoplastic
Advantages of thermoplastic AFO
Lightweight
Shoe easily changeable
Cosmetically acceptable
Total contact increases control
Knee stability readily influenced by minor changes in orthosis or sole of shoes
Disadvantages of thermoplastic AFO
Limited Adjustability
Rigidity can not be increased
Fixed heel height
Intimate fit does not accommodate edema or changes in volume
Localized pressure and callus formations may occur over time
Insensitive skin must be closely monitored for breakdown
Indications for Articulated Plastic AFO
Weakness in one of dorsi or plantarflexion
Medial lateral instability of ankle
Contraindications for articulated thermoplastic AFO
Uncontrolled spasticity- motion at ankle increases spasticity
Severe pronation in midstance from uncontrolled tibial internal rotation
Genu valgus or varus deformities
Over lengthening of the Achilles tendon
Indication for floor reaction AFO
MInimum Grade 3 quads
with Over lengthening of the achilles
Crouch Gait
Contraindications for floor reaction AFO
Flixed flexion contracture of the knee and hip
Tight achilles tendon
Athetoid CP or balance defecit
Primitive reflex synergy patterns
Poor hip extension and poor quads
Adductor Spasticity
Flexible Genu valgum/varum
Floor reaction AFO Advantages
Greater energy efficiency than KAFO
Cosmetically acceptable
Floor reaction AFO Disadvantages
Dislocation of the tibia posteriorly on the femur
Difficulty in donning and doffing with spastic CP children
Ankle angle and pretibial shell not adjustable once fabricated
Anterior shell/PTB Indications
Provides rigid ankle support
Charcot joint, severely painful
External support for tibial fractures (dsital 2/3 only)
Additional support of ORIF (open rediuction internal fixation) of tibia, distal to tibial tubercle
Post operative fusions of the ankle
Avascular necrosis of the talar body
PTB AFO contraindications
Unreliable patient
Unstable fracture pattern
Total unloading ankle/foot inadvisable
Severe pitting or fluctuating edema
Arthritic condition of knee/unable to accept weight-bearing
PTB AFO Advantages
Removable for dressing/wound care
Light weight
Cosmetic
Circumferential adjustment
PTB AFO Disadvantages
Dependent on patient reliability
Shoe requires a soft heel and rocker bottom sole
More difficult to fit in shoe
Can be hot and cause discomfort
More frequent visit for adjustments, due to decreases in volume, to maintain suspension
Types of Conventional AFO stirrups
Solid - does not allow for shoes changes, length dependent on m-l stability
Split - allows detachment of uprights, shoe exchange possible, can be incorporated into a plastic foot section so that patient no required to modify shoes to accommodate stirrups/uprights
Round - attached directly to uprights without ankle joints
- results in axis distal to anatomical axis
Conventional Solid Ankle
No motion allowed
Indicated when motion creates pain, immobilization following fracture or fusion
Generally not recommended for paralytic conditions
Conventional Limited Motion
Permits limited plantar/dorsiflexion as desired
Indicated to limite painful ROm for weak muscle control
Degree of motion determined prior to fabrication
Conventional Free Motion
Does not limit motion in sagittal plane
Motion limited only in the frontal plane provided
Dorsiflexion Assist (Klenzak)
Spring dorsiflexion with plantarflexion limited to 105 degrees
Used with weak or absent dorsiflexors
Not used in conjunction with spastic muscles
Plantarflexion stop
Unlimited dorsiflexion
Plantar flexion limited to 90 degrees
Used with absent dorsiflexors when spring action may trigger spastic gastroc soleus
Dorsiflexsion stop
Free palntar flexion
Dorsiflexion limited to 90 degrees or neutral
Active dorsiflexion, absent plantarflexors
Stabilize against undesirable dorsiflexion in the later half of stance phase
Prevents early knee flexion and subsequent limp
Double Action
Designed as spring loaded device to offer dorsi/plantar flexion assist
Plantar flexion assist is ineffective due to the GRF at push off
Springs replaced with pins to act as dorsi/plantar stops, resulting in similar function to a limited motion joint
Easier to adjust and readjust
Long tongue stirrup indicated with limited motion joint
Counteracting COntractures
Most effective method of treating contracture with an orthosis is a double adjustable ankle
Mechanical ankle joints are adjustable to accommodate changes made in plantar/dorsiflexion
As contractures are reduced or stretched out, mechanical ankle joint can be set to hold these corrections
Fixed deformities or contractures may be effectively treated with surgery
Counteracting Spasticity
AFOs not intended to counteract significant spasticity
Mild spasticity or hypertonus may be controlled with orthosis
Generally, spasticity cannot be overpowered manually, AFO may not effectively control extremity
TONE REDUCING AFO or inhibitive casting technique
SMO
Incorporate modifications that inhibit tonic reflexes of the foot (Duncan, 1960)
Tonic reflexes involved in posturing reflexes and automatic movements to changes of COM and position of body when ambulating
Modifying foot plate to inhibit reflexes, assumed patient with upper motor neuron lesion will inhibit primitive reflex and synergistic patterns and obtain voluntary motor control and more normal gait patter
Dorsiflexion reflex- 1st MTP
Toe Grasp reflex - 3rd MTP
Eversion Reflex - 5th MTP
Inversion Reflex- Center of
Heel
Charcot Ankle
Solid ankle orthosis
Either conventional or plastic with anterior trimlines, polyethylene anterior shell is indicated
Tibial Torsion
Cannot be effectively controlled with an orthosis
