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KNEE ANKLE FOOT ORTHOSIS.pptx

A KAFO is a leg brace that controls knee and ankle movement. It is more energy intensive than FOs or AFOs due to compensatory movements needed to swing the leg. There are three main types - conventional metal, thermoplastic shell, and thermosetting shell. The document describes the components, designs, and joints of KAFOs including indications, advantages, and disadvantages of each. The goal is to select the appropriate KAFO design based on the individual needs of the patient.

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KNEE ANKLE FOOT ORTHOSIS (KAFO)
WHY KAFO? Excessive movement at the knee
INTRODUCTION • DEFINITION: As the name suggests, a KAFO is a device that controls the movements of the knee and ankle joints, and holds the foot in a desired posture.
Qn. compared to FOs and AFOs, why is it seen that energy expenditues using KAFO is much higher than when using FOs and AFOs? Ans: This is due to compensatory movements that must be made in order to swing the limb.
KAFO TYPES
• So far there are three(3) TYPES of the KAFO: depending on the materials CONVETIONAL KAFO THERMOPLASTIC KAFO and THERMOSETTING KAFO.
THE CONVETIONAL KAFO
• Has a metal frame (double upright) that is attached to a shoe via a stirrup system • Metal cuff bands covered with leather to hold the thigh and cuff • Typically, a pair of orthotic ankle joints is used to connect the stirrup to the distal metal upright, and a pair of the orthotic knee joints connect the distal and proximal metal uprights
advantages • Easily to wear • Very strong • Easily adjusted- Can be repaired locally • Most durable • - Cooler than plastic • - Materials available locally
disadvantages • Heavy • Patient cannot easily change the shoe • Cannot wear the device without shoe • Few contact points reduce control • Small points of contact means that forces are concentrated on the small areas and thus pressures are high • - Shoe must be modified • - Difficult to clean • - Less cosmetic
INDICATIONS • - Insensate skin (not absolute) • - Oedema(-for patient with uncontrolled or fluctuating edema) • - Patient preference • When maximum strength and durability are needed • For patient with significant obesity
CONTRAINDICATIONS • - Strong corrective forces needed • - Patient works in wet / muddy environment • - Patient concerned about cosmesis
THERMOPLASTIC KAFO
• This is the shell KAFO,in which the shell is vacuum over the positive modal of the patient limb. • Distal molded shell,which fits over the foot ankle and lower leg, this is basically an AFO section with a proximal anterior strap(usually velcro) closure NOW,depending on the patient’s needs,this distal component may be either a solid ankle or articulating design(ie, AFO with or without joint)
• The proximal molded shell encases the thigh from the greater tronchanter to just above the femoral condyles and typically has a pair of anterior straps(again usually velcro) for closure. - These two molded sections can made from plastic or laminated materials. •metal uprights with knee joints and side bars(made of stainless steel, aluminiun) connect the proximal and distal shells.
advantages • Lighter weight • Interchangeability of shoes • Greater cosmetic • Large forces are distributed and hence reduced pressure on the patient limb • - Close fitting / cosmesis • - Good control of movement • - Plastic easy to adjust • - Easy to clean
disadvantages • Hot and sweaty • Hot and sweaty • - More time spent in manufacture • - Requires workshop to repair • - Materials must be imported
indications • When energy expenditure makes weight of the orthosis an issue • When intimate /total contact fit is needed to make maximum control of the limbStrong corrective forces needed • - Patient works in wet / muddy environment • - Patient preference • - Patient concerned about cosmesis • - Patient doesn’t wear shoes
contraindications • Obese patient • Patient with fluctuating odema • - Insensate skin (not absolute) • - Oedema • - Scarring in contact or high pressure areas
THERMOSETTING KAFO
INDICATIONS • - Patient has weight fluctuations • - Patient preference
CONTRAINDICATIONS • - Insensate skin( not absolute) • - Oedema • - Scarring in contact areas
ADVANTAGES • - Can use normal shoes • - Close fitting • - Good control of movement • - Thigh section cooler
DISADVANTAGES • - More steps in manufacture • - Requires workshop to repair
KAFO DESIGNS • These depend upon the need of the patient ISCHIAL WEIGHT BEARING KAFO ANTERIOR SHELL KAFO POSTERIOR SHELL KAFO
ISCHIAL WEIGHT BEARING KAFO NOTE: When a patient cannot bear weight through the skeletal structure of the leg because of pain, fracture or weakness an Ischial Weight Bearing KAFO can be made. The orthoses can be either conventional or using shells, and uses similar modifications to a TF socket.
INDICATIONS • - hip, knee or ankle pain / damage • - non healed fracture in lower limb
CONTRAINDICATIONS • - hip dislocation • - if weight relief is not required
ADVANTAGES • - can take weight through suitable structure • - quadrilateral proximal area helps to control rotation
DISADVANTAGES • - very large orthosis • - less sitting comfort
Anterior Shell • INDICATIONS - knee collapse - posterior scarring - PCL laxity CONTRAINDICATION • - knee hyperextension • - ACL laxity • - anterior scarring
ADVANTAGES - sitting comfort DISAVANTAGES - difficult to don - pressure on bone area (tibia)
Posterior Shell Indications - knee hyperextension - ACL laxity - anterior scarring Contraindications - knee collapse - posterior scarring - PCL laxity
Advantages - easy to don - all pressures on soft tissue Disadvantages - discomfort when sitting
Each design has advantages and disadvantages, indications and contraindications, and these must be carefully considered when developing the prescription.
KAFO Components DISTAL COMPONENT (which is an AFO section) KNEE COMPONENT (Knee joints) PROXIMAL COMPONENT (thigh section)
DISTAL COMPONENT • AFO section • The choice of AFO design within the KAFO should follow the principles already learned. The control of the foot and ankle must be achieved to provide the patient with a stable base of support. • One key point to bear in mind is that ankle position has a direct relationship to knee and hip position in standing and gait. • If the AFO is dorsi-flexed it will encourage knee and hip flexion. • If the AFO is plantarflexed it will encourage knee extension. • The positioning of the ankle and tibial angulation is very important. The ideal position is to have a line from the Greater Trochanter fall between the navicular and malleolus in midstance.
KNEE COMPONENT • Knee joints One of the key components of a KAFO is the knee joint. As in prosthetics there are many designs and variations, but can be divided into broad categories 1.Single Axis Free motion 2. Polycentric Free motion
SINGLE AXIS FREE MOTION A A
The joint is very simple and allows free movement in the sagittal plane. Most joints have a stop at 180° (full extension) and a good range of flexion. This type of joint would be used in patients who require control of coronal plane movement, or in cases of knee hyperextension, but not control of knee flexion.
Polycentric Free motion A
• The joint has two axes, and thus attempts to mimic the movement of the tibiofemoral joint. This type of joint is used as above.
Posterior Offset joint A
• The posterior offset joint, as the name suggests, has the axis of the joint placed posterior of the line of the uprights. The idea is to move the joints posterior to the GRF, and in this way create stability. For this to work some of the patients body weight must pass through the device. This type of joint is used mostly for patients who have some weakness of knee extensors (at least Grade 3) and good hip extensors
indications • - knee M-L instability • - knee hyperextension • - older patients (improve stability) • - knee extensors > Gd 3+ • - hip extensors > Gd 4 •
contraindication • - knee extensors < Gd 3+ • - hip extensors < Gd4
advantages • - normal swing phase • - simple and easy • - lightweight • - little maintenance
disadvantages • - may collapse on inclines • - not safe on uneven ground • - requires some weight bearing through KAFO structure
DROP LOCK • A
• This type of joint offers a simple locking mechanism, but one that offers a positive lock of knee movement. The joint is single axis and is locked when a ring of metal drops down over the joint, blocking all movement. The lock is easy to operate, as when the patient stands and the uprights are straightened gravity pulls the ring down and into place. In some cases the ring is assisted to drop by the use of a spring. • To unlock the knee the patient has to lift the ring and flex the knee. This requires that the patient has good hand function.
• Indications - knee A-P instability - knee M-L instability - knee hyperextension - knee extensors < Gd 3 - hip extensors < Gd 3
• Contraindications - poor hand function - knee extensors > Gd 3+ - hip extensors > Gd 3
• Advantages - Complete control of knee - low maintenance Disadvantages • - Patient must lift locks • - knee must be fully extended to engage locks • - Can “rattle” • - Can “jam”
BAIL LOCK A
• This type of lock uses a mechanical block within the joint to prevent motion. The block is operated by a lever which sticks out from the posterior side of the joint. These levers are often welded to a metal ring around the posterior aspect of the brace, so that both locks can be operated with one hand, or by knocking the ring against a chair.
Indications • - knee A-P instability • - knee M-L instability • - knee hyperextension • - knee extensors < Gd 3 • - hip extensors < Gd 3 • - poor hand function • • • •
contraindications • - knee extensors > Gd 3+ • - hip extensors > Gd 3 •
advantages • - Complete control of knee • - One handed operation possible • disadvantages • - knee must be fully extended to engage locks • - Can “rattle” • - can be unlocked with bump to posterior. • - bulky / reduced cosmesis
Advanced knee joints • The joints described above are very simple and rely upon basic mechanisms. There has been a lot of money spent on developing better orthotic knee joints. This research has been ongoing for many years. One of the goals of this research has been to develop joints that have stance and/or swing phase controls. However there is very little available that is reliable and affordable. • The biggest problem is that orthotic joints must be thin and small so they don’t affect cosmesis. So the control mechanisms have to be very small. These small parts then have to take large forces, and are prone to failure. •
• Overview - http://www.oandp.com/news The following are some recent attempts at better orthotic knee joints. Look at them on the internet. • /jmcorner/2002-05/1.asp • - http://www.stancecontrol.com/ • Pendulum lock - http://www.spsco.com/press/10-30-02c.html • - http://www.oandp.com/edge/issues/articles/2002-07_14.asp • UTX - http://www.rslsteeper.co.uk (search for “UTX swing”) • - http://www.beckerorthopedic.com/utx/utx.htm • Load Response Knee - http://www.beckerorthopedic.com/knee/load_response.htm • Extension assist - http://www.beckerorthopedic.com/knee/g_knee.htm
ALIGNMENT
Function – To control motion around the knee joint: describe which motion is being controlled – To offload a joint – To prevent deformity • To increase stability
KNEE ANKLE FOOT ORTHOSIS.pptx