Foundations for Ankle Foot Orthoses

Original Editor - Carin Hunter based on the course by Donna Fisher
Top Contributors - Carin Hunter, Jess Bell, Kim Jackson and Tarina van der Stockt

Types of AFO

• AFO - Ankle Foot Orthosis
• GRAFO - Ground Reaction Ankle Foot Orthosis
• DAFO - Dynamic Ankle Foot Orthosis
• SMAFO- Supramalleolar Ankle Foot Orthosis
• Custom Made
• Off the shelf

Orthotic Assessment  

Passive Assessment:

• Range of Motion (ROM)
• Muscle Power
• Proprioception
• Sensation
• Leg Length
• ROM Foot/Ankle

Active Assessment:

• Level of mobility
• Gait Pattern
• Compensation Mechanisms o Instability
• Risk of injury
• Pain

Gait Cycle

Normal Gait Cycle:

Pathological Gait Cycle:

• Pain
• Joint ROM limitations
• Muscle weakness/ paralysis
• Neurological deficit
• Sensory deficit
• Leg length  

Pathologies

• Paediatrics:
  • Neural Tube Defect / Spina Bifida
  • Cerebral Palsy
  • Muscular Dystrophy
• Cerebral Vascular Accident – Early intervention
• Multiple Sclerosis – Progressive
• Polio  
• Neuropathy
  • HMSN
  • Diabetes
  • Tumor
• Trauma
  • Nerve injury
  • Pain
  • Instability

Goal setting/ Prescription

1. Positioning
2. Provide Support
3. Prevent contractures
4. Improve mobility
5. Increase stability
6. Patient Needs

3 point force system

• Stabilizes a joint or segment

• Reduces angular rotation

• Medio-lateral or antero-posterior

• Longer the lever arm the greater the force

• Pressure= Force /Area

Commonly Used Ankle Foot Orthosis

1. Flexible A.F.O.
2. Rigid A.F.O.
3. Jointed A.F.O.

1. Flexible AFO

Design/ Manufacture

1. Custom made  
2. Mostly manufactured from a plaster model
3. Polypropylene/ lamination/ Carbon Fibre
4. 3 point force system

Prescription Criteria For A Flexible A.F.O.

1. Drop foot
2. Mobile foot/ankle
3. No tendency to valgus or varus

Common conditions include

1. CVA
2. Nerve injury/dysfunction
3. Paediatrics

2. Rigid A.F.O.

Prescription Criteria For A Rigid A.F.O.

1. Tightness in T.A.
2. Tendency to valgus
3. Tendency to varus
4. Excessive dorsiflexion
5. Slight tendency to flexion at knee

Common Conditions

1. CP
2. NTD
3. Stroke
4. Trauma
5. Pain

Rigid AFO +/- Anterior Shell

1. Tightness in T.A.
2. Tendency to valgus
3. Tendency to varus
4. Excessive dorsiflexion
5. Crouch/ Flexion at knees

(Ries 2019)

Used for

1. Muscle Tightness- Dynamic/Fixed
   1. Crouch/ Equinus
   2. Gait Hyper-extension/ Escape Valgus
2. Valgus Deformities
   1. Rocker Bottom Foot
   2. Hyper-mobility
   3. Escape Valgus
      1. Compensatory movement
      2. Driven by tight TA
      3. Can alter foot structure  
      4. Can result in long term issues
3. Varus Deformities
   1. Correctable deformity
   2. Difficult to control
   3. Accommodate deformity
4. Varus Deformity
5. Crouch/Excessive Dorsiflexion

Tuning/ Optimising AFOs  

o There is evidence that tuning  AFOs can significantly improve  gait and their effect at the  proximal joints.  

(Owen 2002, Stallard 2003, Butler 2007,  Jagadamma 2009)  

Tuning/ Optimising AFO’S - AFOFC

3. Jointed A.F.O.

Prescription Criteria For A Jointed A.F.O.

1. ROM in ankle joint
2. Tendency to valgus
3. Tendency to varus
4. Tendency to Crouch

Prescription criteria for Jointed AFO and DAFO/SMAFO

1. Hyper mobile foot/ankle
2. Ankle to plantargrade
3. Medio-lateral instability

In Conclusion