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

2. 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

3. 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.)

4. 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

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

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

7. 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

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

9. 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

10. 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

11. 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)

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

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

14. 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

15. Ankle-Foot Orthoses (AFOs)
Metal
Plastic

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

17. Metal AFO
Uprights
Aluminum - lightweight
Stainless Steel - strong

18. Metal AFO
Stirrups
Solid - stability
Split – shoe change

19. Metal AFO
Ankle Joints
Free Motion

20. Metal AFO
Ankle Joints
Dorsi-flexion Assist

21. Metal AFO
Ankle Joints
Double-action

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

24. Metal AFO
Auxillary Controls
Laminated Footplate

25. Metal AFO
Auxillary Controls
Pre-tibial Shell

26. Fitting Criteria for Metal AFOs
Height
Top of calf no less than /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

27. 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

28. Intentionally Blank

29. Intentionally Blank

30. Intentionally Blank

31. Intentionally Blank

32. Plastic AFOs (PAFOs)

33. 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

34. Plastic AFOs (PAFOs)
Solid
Rigid

35. Plastic AFOs (PAFOs)
Solid
Posterior Leafspring (PLS)

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

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

38. Articulated Plastic AFOs
Ankle Joints

39. Articulated Plastic AFOs
Free or limited motion
Variable motion

40. Articulated Plastic AFOs
Free or limited motion
DF Assist
Neutral
Tamarack

41. Articulated Plastic AFOs
Free or limited motion
Oklahoma

42. Articulated Plastic AFOs
Variable Motion
Friddle VM

43. Articulated Plastic AFOs
Variable Motion
Camber Angle

45. Plastic AFOs
Auxiliary Components

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

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

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

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

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

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

52. 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

53. 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