Introduction to Complex Orthoses

Introduction

Complex orthoses are those that serve to assist multiple joints. These types of 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:

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 that will be covered in this course are the KAFO and the HKAFO. KAFOs refer to a knee-ankle-foot orthosis while an HKAFO refers to a hip-knee-ankle-foot orthosis.  

Orthotic Assessment

As complex orthosis are a more substantial orthosis requiring increased skill and experience to fit these devices. The main components of an orthotic fitting for complex orthosis involve the following parameters:

• Medical/Physical: necessary to know the medical condition

• ROM/Muscle Power: to better understand what joints need support

• Biomechanical: understanding the biomechanics of the individual patient and where they need additional support

• Proprioception: understanding by putting the orthosis on, they may not have the same compensatory mechanism which could decrease their proprioception

• Sensation: potential skin breakdown or discomfort

• Leg Length: if necessary to compensate for leg length discrepancy

** 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 Orthosis

Derotation Orthosis (Twister)

A derotation orthosis is used to control internal and external rotation. This orthosis consists of an AFO section, a free knee joint and a pelvic section to influence rotation at the hip. The most common diagnosis that utilises a derotation orthosis is a neural-tube defect. External tibial torsion is commonly seen in people with Spina-Bifida. Compensatory motions resulting from external tibial torsion include:

• Trunk lean toward stance phase
• Dynamic pelvic internal rotation
• Knee flexion during stance phase
• Ankle and hindfoot valgus

Additionally, children with Spina-Bifida typically present with hip extensor and abductor weakness resulting in compensatory excessive motion elsewhere. This superfluous motion leads to increased energy expenditure and difficulty keeping up with their peers without disabilities.

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:

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

An important aspect of fitting a KAFO is assessing the strength of the quads. Quad strength of 3 or less indicates the patient can not keep their knee in extension and support their body weight during gait. Therefore, the KAFO would need to have a locked knee joint. If the quads are higher than a three, a free knee joint will allow the knee to flex and provide some mediolateral support during stance.

Different types of KAFOs.  

One-piece KAFO

One-piece KAFO's have the following properties:

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

** Common diagnosis where you might utilise this type of orthosis is cerebral palsy, neural-tube defect or Blounts. 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 over 10 years old.

Jointed KAFO

There are two types of jointed KAFO's, non-weight bearing and weight-bearing.

1. Non-weight bearing KAFO's can have a rigid of semi-flexible ankle and would be used for:
   • Knee instability leading to flexion or hyperextension
   • Knee instability leading to varus or valgus

• Common conditions where you would prescribe this type of orthosis would be polio, nerve damage, knee instability and neural-tube defect. Post-polio patients are at high risk for falls (70%) due to the extensive weakness in their affected leg, mainly knee extensors. These patients will display an asymmetrical gait, reduced proprioceptive input, balance issues, contractures and musculoskeletal deformities. (OFRAN)

1. Weight-bearing KAFOs :
   1. Ischial seat for weight-bearing secondary to weak abductors
   2. Rigid or semi-flexible ankle  
   3. Provide good hip and knee support

• Common diagnosis where you might see this type of KAFO being used is polio, Trendelenburg gait, neural-tube defect and arthrogryposis. Arthgroyphosis is a disorder characterized by multiple congenital joint contractures. Children who present with arthgroyphosis commonly have clubfoot, equinovarus foot and congenital vertical talus. (Perootti)

HKAFO

HKAFO (hip-knee-ankle-foot orthosis) is a complex orthosis which can control all joints of the lower limb, pelvis and spine. With an HFAFO, 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 that would use an HKAFO are typically wheelchair users and 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 creates huge energy expenditure, therefore, most patients discontinue by age 14. Additionally, gait is slow with an HKAFO making it difficult to keep up with peers, whereas a wheelchair is faster. Typically HKAFOs will be used with pediatric patients, with neural-tube defects and paraplegia.

A unique type of HKAFO is a reciprocating gait orthosis. This type of orthosis allows more of a normalized reciprocating gait pattern. In an RGO, one leg can pass in front of the other with a normal rotation. Prescriptions for an RGO would include patients with weakness in lower limbs with the following:

• good upper limb strength
• good motivation to walk
• parental support and
• no joint contractures.

Typical common conditions where you might see an RGO would include paraplegia or neural-tube defect.

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