Introduction to Complex Orthoses

Original Editor - Robin Tacchetti based on the course by Donna Fisher
Top Contributors - Robin Tacchetti, Jess Bell and Kim Jackson

Introduction

Complex orthoses are devices designed to assist multiple joints. These orthoses are not as common as ankle-foot orthoses (AFOs). They are designed for patients with extensive weakness in the lower limbs. The purpose of these complex orthoses are to:

1. Provide support and protection
2. Optimally align the joints
3. Maintain a functional position
4. Provide stability
5. Reduce pain

Two types of complex orthoses will be discussed in this page: the knee-ankle-foot orthosis (KAFO) and the hip-knee-ankle-foot orthosis (HKAFO). 

Orthotic Assessment

Complex orthoses are more substantial devices. Thus, more skill and experience are required to fit these devices. When fitting a complex orthosis, the main components of an orthotic assessment include:

• Medical / physical: it is necessary to know the medical condition

• Range of motion (ROM) / muscle power: to better understand what joints need support:
  • For ROM:
    • Foot/ankle: dorsiflexion / plantarflexion, inversion / eversion
    • Knee: extension / flexion, instability
    • Hip: extension / flexion, adduction / abduction
    • Look at any fixed contractures: hip, knee or ankle
  • For muscle power:
    • Oxford Scale
    • Which joints are affected by weakness?
    • Power < 3 = not functional
    • Strength determines the design / type of joints used in the orthosis

• Biomechanical: it is essential to understand the biomechanics of each patient and to determine where they need additional support

• Proprioception: when patients put an orthosis on that covers the ankle, foot, knee and hip, they lose some compensatory ability - proprioception is essential to ensure that the patient can stand / walk while wearing the brace

• Sensation: be aware of potential skin breakdown or discomfort

• Leg length: it may be necessary to compensate for leg length discrepancy
• 3-Point Force System: see the linked article for information on where exactly to apply the force and counterforces

** Contractures can be a contraindication to some complex orthoses when using a rigid or locked section because the compensatory mechanism might be taken away.

Types of Complex Orthoses

Derotation Orthosis (Twister)

Derotation orthosis (twister).

A derotation orthosis is used to control internal and external rotation. This lesser-known orthosis consists of an AFO section, a free knee joint and a pelvic section to influence rotation at the hip. These devices are most commonly used for persons with neural-tube defect and are usually fitted in children aged around 2 or 3 years old. External tibial torsion is commonly seen in people with spina bifida. Compensatory motions resulting from external tibial torsion include:

• Trunk lean towards stance phase
• Dynamic pelvic rotation
• Internal hip rotation
• Knee flexion during stance phase
• Valgus at the ankle and hindfoot

Additionally, children with spina bifida typically present with hip extensor and abductor weakness resulting in compensatory motion elsewhere. This weakness and excessive motion lead to increased energy expenditure and decreased gait speed compared to age-matched peers without disability.

KAFO (Knee-Ankle-Foot Orthosis)

Knee-ankle-foot orthoses (KAFOs) are used for stance control. These types of orthoses are generally prescribed for the following reasons:

• Instability of the knee
• Muscle weakness at the ankle / knee / hip
• Knee contracture
• Knee hyperextension
• Foot and ankle control
• To provide some hip support

An important aspect of fitting a KAFO is assessing the strength of the quadriceps. Quadriceps strength < 3 on the Oxford scale indicates that the patient cannot keep their knee in extension and support their body weight during gait. Therefore, the KAFO would need to have a locked knee joint. If quadriceps strength is 3 or greater than a KAFO with a free knee joint will allow the patient to flex their knee and provide some mediolateral support during stance.

Different types of KAFOs  

One-Piece KAFO

One-piece KAFO (knee-ankle-foot orthosis).

One-piece KAFOs have the following features:

• No moving parts
• Straight leg in walking
• Typically used for contracture control or as a night splint
• Passive device

** This type of device might be utilised in conditions such as: cerebral palsy, neural-tube defect or Blount's disease. Infantile Blount's disease is seen in children between 2-5 years old and presents as pathologic genu varum. Adolescent Blount's disease is typically less severe and seen in children aged over 10 years.

Jointed KAFO

There are two types of jointed KAFOs: non-weight bearing and weight-bearing. Both of these orthoses can have a rigid or semi-flexible ankle.

Non-Weight Bearing KAFOs

Non-weight bearing KAFOs are used for knee instability when the knee moves into flexion, hyperextension, varus or valgus.

** This device might be prescribed for: polio, nerve damage, knee instability and neural-tube defect. Post-polio patients are at high risk for falls; the frequency of falls in individuals with post-polio syndrome is believed to be around 70%. This is due to extensive weakness in the affected leg (mainly the knee extensors). These patients will display an asymmetrical gait, reduced proprioceptive input, balance issues, contractures and musculoskeletal deformities.

Weight-Bearing KAFOs

Weight-bearing KAFO (knee-ankle-foot orthosis).

Weight-bearing KAFOs are used to provide hip and knee support. They generally have locking knee joints and have an ischial seat for weight-bearing, thus accommodating weakness in the hip abductor muscles.

** This type of KAFO is commonly used for: polio, Trendelenburg gait, neural-tube defect and arthrogryposis. Arthrogryposis is a disorder characterised by multiple congenital joint contractures with weakness in the hip and knee extensors. Children who present with arthrogryposis commonly have clubfoot (equinovarus foot) and plantar flexor muscle weakness.

See the video below by OrthoMedics for a demonstration of a locked vs. unlocked KAFO

HKAFO (Hip-Knee-Ankle-Foot Orthosis)

HKAFO (hip-knee-ankle-foot orthosis).

HKAFOs (hip-knee-ankle-foot orthosis) are complex orthoses which control the joints of the lower limb, pelvis and spine. With an HKAFO, the hip, knee and ankle are all locked or rigid making it a static device. The HKAFO aims to provide support for the trunk and lower limbs. Patients who would use an HKAFO are typically wheelchair users and are unable to walk without these devices. Advantages to using HKAFOs include the following:

• Standing / walking
• Control of joints / contractures
• Ability to be at the height of peers
• Aids in bone density
• Weight control / fitness
• Bladder / bowel development

Walking with HKAFOs is associated with huge energy expenditure. Therefore, most patients discontinue their use by the age of 14. Additionally, gait is slow with an HKAFO making it difficult for patients to keep up with peers, compared to using a wheelchair, which is faster.

** Typically HKAFOs will be used for paediatric patients, individuals with neural-tube defects and paraplegia.

RGO (Reciprocating Gait Orthosis)

Reciprocating gait orthosis (RGO).

A unique type of HKAFO is a reciprocating gait orthosis (RGO). This type of orthosis allows a more normalised reciprocating gait pattern. With an RGO, one leg can pass in front of the other, creating a more typical pelvic rotation. Populations who would benefit from an RGO include patients with weakness in the lower limbs and the following:

• Good upper limb strength
• Good motivation to walk
• Parental support
• No joint contractures

** RGOs are commonly used in individuals with paraplegia or neural-tube defect.

Watch the video below by Kare Prosthetics and Orthotics to see two examples of HKAFO with RGO.

Resources

• Foundations for Ankle Foot Orthoses
• Introduction to Foot Orthoses
• Introduction to Knee Ankle Foot Orthoses
• Introduction to Orthotics