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Classification of Lower-Limb Orthoses

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I. By Anatomical Region (Regional Classification)

1. Foot Orthoses (FO)

• Extra-depth shoes (high toe box): dissipate pressure over bony prominences; recommended for diabetic patients
• SACH heels: absorb initial loading shock; lessen force transmission to the midfoot
• Rocker soles: reduce bending forces on arthritic/stiff midfoot; used for metatarsalgia, hallux rigidus, and forefoot problems; must be rigid to be effective
• Medial heel out-flaring: treats severe flatfoot; used with a foot orthosis

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2. Ankle-Foot Orthosis (AFO)

• Metal double-upright bars attached to the shoe (greater rigidity; better for mediolateral instability; adjustable; heavier)
• Thermoplastic elastomer (TPE) shell fitting inside a shoe (lightweight; cosmetically preferred)

• Footdrop (any cause - stroke, peripheral nerve palsy, Charcot-Marie-Tooth, SCI)
• Plantar spasticity after stroke or spinal cord injury
• Post-hindfoot arthrodesis (absorb GRF, protect fusion sites, protect midfoot)
• Ankle osteoarthritis (with rocker-bottom shoe)
• Mediolateral subtalar instability
• Inadequate dorsiflexion for heel contact or toe clearance in swing phase

• Slight plantar flexion → extends the knee earlier (helps knee buckling in stance)
• 5 degrees of dorsiflexion → decreases knee hyperextension (prevents snap-back in midstance)

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3. Knee Orthosis (KO)

• Relieve pain in knee osteoarthritis (unloader braces offload medial/lateral compartment)
• Stabilize the patella-deficient knee
• Stabilize the ACL-deficient knee
• Facilitate post-operative rehabilitation

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4. Knee-Ankle-Foot Orthosis (KAFO)

• Controls unstable knee joint (primary indication)
• Provides mediolateral stability of the knee
• Prescribed amounts of flexion or extension control
• Stabilizes ankle and foot in plantigrade position (prevents equinus/equinovarus)
• Provides stability for patients with proximal muscle weakness

In myelomeningocele: KAFO is used for the L3 level (household ambulation); AFO suffices for L4-L5 (community ambulation); HKAFO is needed for L1-L2 (non-functional/therapeutic walking).

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5. Hip-Knee-Ankle-Foot Orthosis (HKAFO)

• Provides hip and pelvic stability
• Enables therapeutic upright activities for high-level paralysis

• Cumbersome; rarely used by adult paraplegics because of high energy expenditure for minimal functional gain
• In experimental settings: used with implanted electrodes and computerized functional stimulation for SCI patients

• Modified HKAFO with wire cables linking hip flexion on one side to hip extension on the contralateral side
• Used in children with upper lumbar myelomeningocele (L1-L2) for therapeutic upright activities and simulated walking
• Also used in select thoracic-level SCI patients for short-distance ambulation

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6. Hip Orthosis (HO)

• Pavlik harness: the mainstay for early treatment of developmental dysplasia of the hip (DDH) in infants; holds the hip in flexion and abduction
• Abduction orthoses (e.g., Rhino cruiser, Denis Browne bar): for DDH after Pavlik harness treatment or post-reduction
• Hip spica orthoses: post-operative hip containment

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II. By Functional Purpose (Functional Classification)

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III. Summary Hierarchy by Region

Lower-Limb Orthoses
├── Foot Orthosis (FO)
│     ├── Rigid
│     ├── Semirigid
│     └── Soft
├── Ankle-Foot Orthosis (AFO)
│     ├── Rigid / solid ankle
│     ├── Posterior leaf-spring
│     ├── Hinged (articulated)
│     └── Plantar-flexion-stop
├── Knee Orthosis (KO)
│     ├── Unloader (OA)
│     ├── Patellar stabilizing
│     └── Ligamentous (ACL)
├── Knee-Ankle-Foot Orthosis (KAFO)
│     └── With various knee-lock designs
├── Hip-Knee-Ankle-Foot Orthosis (HKAFO)
│     └── Reciprocating Gait Orthosis (RGO) [modified HKAFO]
└── Hip Orthosis (HO)
      ├── Pavlik harness
      └── Abduction orthoses

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Key Principles

1. Orthoses are not indicated for fixed deformities that cannot be passively corrected or for spastic deformities that cannot be easily controlled manually.
2. Orthoses are named by the joints they control, the function they provide, and the method of obtaining control - e.g., a short-leg below-knee brace = AFO.
3. Orthoses may be static, static-progressive, or dynamic in their mechanism.
4. Material choice (metal uprights vs. thermoplastic) affects rigidity, weight, adjustability, and cosmesis - each has distinct clinical roles.

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Classification of Lower-Limb Orthoses

Introduction (2 marks)

• Protect long bones or unstable joints
• Support flexible deformities
• Substitute for a functional task (e.g., weak muscle group)
• Facilitate fracture healing while allowing function

Key principle: Orthoses are NOT indicated for fixed deformities that cannot be passively corrected, or for spastic deformities that cannot be easily controlled manually.

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I. Classification by Anatomical Region (12 marks)

A. Shoes and Shoe Modifications

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B. Foot Orthosis (FO)

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C. Ankle-Foot Orthosis (AFO) (Most common lower-limb orthosis)

• Metal double-upright attached to shoe: greater rigidity, adjustable, better for severe mediolateral instability, heavier
• Thermoplastic elastomer (TPE) shell: lightweight, cosmetic, fits inside shoe, trim lines determine control level

• Angling AFO in slight plantar flexion → extends the knee earlier in stance (treats knee buckling in hemiplegia)
• Angling AFO in 5° dorsiflexion → reduces knee hyperextension / snap-back in midstance

1. Footdrop (any cause - CVA, SCI, peroneal palsy, Charcot-Marie-Tooth disease)
2. Plantar spasticity (CVA, SCI)
3. Post-hindfoot arthrodesis (absorbs GRF, protects fusion and midfoot)
4. Ankle arthritis (with rocker-bottom shoe)
5. Mediolateral subtalar instability
6. Toe clearance failure in swing phase

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D. Knee Orthosis (KO)

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E. Knee-Ankle-Foot Orthosis (KAFO)

• Mediolateral stability of the knee
• Prescribed flexion or extension control at the knee
• Stabilizes ankle-foot in plantigrade position
• Prevents progressive equinus and equinovarus deformities

• Poliomyelitis (quadriceps/proximal weakness)
• Spinal cord injury (SCI) - thoracic/lumbar paraplegia
• Muscular dystrophy
• Myelomeningocele - L3 level (household ambulation)
• Severe hemiplegia with knee snap-back
• Supplemented with pelvic band/hip locks when hip control also needed

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F. Hip-Knee-Ankle-Foot Orthosis (HKAFO)

• Hip and pelvic stability
• Enables therapeutic upright posture and simulated walking

• A modified HKAFO with wire cables (or linkage system) coupling hip flexion on one side to hip extension on the contralateral side
• Translates trunk shift and upper limb effort into reciprocal stepping motion
• Used in children with upper lumbar myelomeningocele (L1-L2) for therapeutic ambulation and as a complement to wheelchair use
• Also used in select thoracic-level SCI patients
• The Walkabout device acts as an RGO

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G. Hip Orthosis (HO)

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II. Classification by Functional Mechanism (4 marks)

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III. Myelodysplasia - Orthosis Level Reference Table (2 marks)

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Summary Diagram

LOWER-LIMB ORTHOSES
│
├─ SHOES / SHOE MODIFICATIONS
│     └─ SACH heel, Rocker sole, Extra-depth, Medial heel flare
│
├─ FOOT ORTHOSIS (FO)
│     ├─ Rigid
│     ├─ Semirigid
│     └─ Soft
│
├─ ANKLE-FOOT ORTHOSIS (AFO) ← Most common
│     ├─ Rigid / Solid-ankle
│     ├─ Posterior Leaf Spring
│     ├─ Hinged (articulated)
│     ├─ Ground Reaction (GRAFO)
│     ├─ Supra-malleolar (SMO)
│     └─ Arizona brace
│
├─ KNEE ORTHOSIS (KO)
│     ├─ Unloader (OA)
│     ├─ Patellar stabilizing
│     └─ Ligamentous (ACL)
│
├─ KNEE-ANKLE-FOOT ORTHOSIS (KAFO)
│     └─ Designs: Drop-lock / Bail-lock / Ratchet / Stance-control
│
├─ HIP-KNEE-ANKLE-FOOT ORTHOSIS (HKAFO)
│     └─ Reciprocating Gait Orthosis (RGO) — modified HKAFO
│
└─ HIP ORTHOSIS (HO)
      ├─ Pavlik harness
      ├─ Rigid abduction orthosis
      └─ Containment orthoses (Perthes)

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