KOs and KAFOs Flashcards
KO for A/P instability, M/L instability, Painful Arthritic knees
ADVANTAGES
Increases proprioception
Helps limit excessive rotation
Force Couple applied can unload knee joint space
DISADVANTAGES
Suspension
Difficult to ensure how much rotational stabilization is really taking place
KO for Knee Hyperextension
ADVANTAGES
Knee joint limits knee extension
Can add lock mechanism
DISADVANTAGES
Suspension
KO for Weak or absent quadriceps
ADVANTAGES
Knee lock stability
Extension assist for improved performance
DISADVANTAGES
Suspension
KAFO designs
Conventional- metal and leather components
Plastic - metal uprights with plastic AFO and thigh sections
Hybrid - Combination of both
Hybrid
KAFO Conventional Indications
Obese patient
Heavy users
Uncontrolled edema
KAFO Conventional Contraindications
Need to conserve energy
Severe angular deformity
KAFO Conventional Advantages
Decreased skin contact
More Breathable
Stronger
KAFO Conventional Disadvantages
Heavy
Attached to shoe
Corrective pads and straps needed to control angular deformity at knee and ankle
KAFO Plastic Indications
Knee instability
Genu recurvatum > 30 degrees, not controlled by AFO
Protection of Total Knee reconstruction
KAFO Plastic Contraindications
Plastic - uncontrolled edema
Obese patient
Correction of severe angular deformity genu valgum/varum
Early spinal cord injury
KAFO Plastic Advantages
LIghtweight
Cosmetic
Interchangeable shoes
KAFO Plastic Disadvantages
Hot
Angular deformity should be first corrected
KAFO Offset Free Knee Joint Indications
Unilateral paralysis
Near vertical hip and trunk alignment
Absence of knee flexion contracture
A plantargrade foot
KAFO Offset Free Knee Joint Contraindications
Hip flexion contracture
Knee flexion contracture
Plantar flexion contracture
KAFO Offset Free Knee Joint Advantages
Decreased energy expenditure
Sit/stand is easier
Stair ascend/descend in easier
More normal gait appearance
KAFO Offset Free Knee Joint Disadvantages
Walking speed is restricted to advancement of swing leg
Ramps are out of the question
KAFO Components
Distal tibial section similar to AFO
Proximal femoral section includes knee joints with proximal and distal thigh bands
Steel or aluminum uprights
Knee straps/pads
Weight bearing brim (if necessary)
KAFO Accessories
Infrapatellar and supra-patellar straps help stabilize knee
Double knee strap (2D control, flexion and valgus control)
Ankle strap keeps foot in brace
Heel wedges to modify angle for balance
KAFO Indicators
Unstable knee in flexion
Knee hyperextension
Medial/Lateral knee instabilities (Genu Valgum/Varum)
Axial unlaoding KAFOs (Ischial weight Bearing Brim)
Spinal Cord Injury
KAFO Indicators - Unstable knee in flexion
Stance phase: weak pretibial and calf muscles along with weak quadriceps
Weak hip extensors require modified standing position in bilateral KAFOs
KAFO Indicators - Knee Hyperextension
Indications for KAFO/KO when the knee hyperextension is greater than 15 degrees
KAFO is chosen if ankle weakness or KO suspension are problems
KAFO Indicators - Medial/lateral knee instabilities (Genu Valgum/Varum)
Require 3PP systems to stabilize/correct leg
The longer the lever arm, the less force is required to stabilize/correct leg
Axial unloading KAFOs(Ischial Weight Bearing Brim)
Gaol is to reduce the load taken on the distal apsect of the limb or reduce the load on the hip joint itself
Ischial weight bearing brims
- Ischial ring
- Ischial containment
- Quadrilateral brim
KAFO- Spinal Cord Injury
Hip flexion contractures than prevent full hip extension may prevent the paraplegic client from ambulating
Spasms will help allow client to stand even when their muscle strength is below normal
Few clients ambulate with lesions with lesions T2 or above
Lesions from T3 to T11 may use bilateral KAFOs for short distance for exercise
Craig Scott Orthosis
- conventional design using offset knee joints with bail locks
- there is no distal thigh band, only a proximal thigh band and anterior pretibial band
Indications for Locked Knee
Upper extremity and trunk too weak or unstable to balance over the hip
Patient needs to lean back behind the knee joint to stabilize the hip
Hip and knee flexion contractures
Plantarflexion contracture
Bilateral lower extremity paralysis
Ischial Weight Bearing Brims
- Ischial Ring (Thomas Ring)
- Ischial Containment Brim
- Quadrilateral Brim
- Patten Bottom with Ischial Brim
Ischial Ring (Thomas Ring)
2 inch metal ring covered with leather and padding
Advantage- cool with small surface area
Disadvantage- small surface area provides limited support and creates high pressure on ischium
Ischial Containment Brim
Custom molded or prefabricated shell contains ischium
Advantages- good rotation control and axial loading due to skeletal contours
Disadvantages- difficult to fit
Quadrilateral Brim
Quadrilateral shape allow for the ischium to sit on the posterior ledge of brim
Advantages- easier to fit than ischial containment and good rotation control
Disadvantages- can be difficult to maintain ischial contact and prevent slipping off posterior ledge (Especially with hip flexion contractures)
Patten Bottom with Ischial Brim
Foot floats in between uprights and above metal foot plate
Advantage- 100% unloading of the leg as foot does not contact ground
Disadvantage - cumbersome, raises the affected side
Stabilization of flail knee without use of knee extension moment and free-knee joint
Off set free knee joint
Ankle in plantarflexion with maximum rigidity
Stabilization of flail knee without use of use of knee extension moment and free knee joint
Off set knee with lock
Free knee with lock
Prevention of Genu Recurvatum
Off-set free knee joint
Knee lock unnecessary in pure Genu recurvatum
Knee lock may be needed if G Recurvatum is associated with extensor weakness
Ankle in neutral or DF to prevent knee extension moment
Reduction of Knee Flexion Contracture
Adjustable to correct contracture
Control of Genu Valgum
Use of lock optional, dependent on severity of problem and associated deficits
Control of Genu Varum
Use of knee lock optional, dependent on severity of the problem and associated deficits
Free Motion
Function
Full flexion, 0 degree extension stop
Advantage
Full range of knee motion
Disadvantage
Cannot be locked
Polycentric
2 axes move center of rotation closer to anatomical knee axis
Advantage
Better Knee motion
Bulky
Off-set
Function
Free knee joint-inherently stable due to extension moment with joint position posterior to weight line of body
Advantage
Inherently stable for mild knee problems, good for hyperextension control
Disadvantage
Can’t guarantee knee staying extended all the time
Off-set
Free knee joint-inherently stable due to extension moment with joint position posterior to weight line of body
Advantage
Inherently stable for mild knee problems, good for hyperextension control
Disadvantage
Can’t guarantee knee staying extended all the time
Dial
Adjustable dial to change knee joint flexion/extension angles
Locking options available
Advantage
Ability to adjust knee angle after brace is made, good for knee flexion contracture
Disadvantage
Rachet teeth in dial can wear out faster than regular knee joints, especially after multiple adjsutments
Drop (ring) locks
Rings around knee joint drop down automatically with gravity, but must be manually lifted to unlock
Advantages
Strong
Simple
Disadvantages
Requires 2 hands to unlock (not for hemiplegia)
Unlocking hard for spastic clients
Must have full knee extension range to work
Cable Release Drop Locks
Cable attached to each side of drop lock allows the locks to be lifted at the same time
One hand can operate locks
Not as bulky as spring loaded bail lock
Difficult to unlock if leg does not have full extension
Must grab cable through trousers
Spring lever (bail lock)
Automatic spring loaded lock, disengaged by manually lifting a rigid metal bar posterior to the knee
Advantage
Easy to open, unilateral or bilateral AKFO use
Can open by leaning against wheelchair
No bending at hip to unlock
Disadvantages
Bulky underneath trousers
If bilateral KAFOs, bails can catch each other
Wears faster than drop locks
Stance Control Knee Joints Indications
Isolated quad weakness
Incomplete spinal cord injury
Polio/post-polio
CVA
Peripheral Paresis/Paralysis
Nerve Inflammation
Neurological Failures
Myopathies
MS or similar diseases
Must be able to initiate swing thru
Must have fair or better hip flexor strength
Contraindications
Knee flexion contracture > 10 degrees
Central Paralysis
Hip flexion contracture
Hip muscular involvement
Poor Balance/Coordination
Weight-bearing orthosis
Uncorrectable Genu Varum/Valgum > 10 degrees
Significant cognitive impairment
Stance Control Knee Joints General
Usually for isolated quad weakness
Most joints lock on initial contact with unlocking at terminal stance when dorsiflexion occurs in conjunction with extension moments at the knee
Most joints require hip extensor control in order to neutralize forces across the orthotic joint
Examples of Commercially Available Stance Control Knee Joints
Ottobock Free Walk
Horton Technology Inc Stance Control
Horton Technology Inc Smart Knee
Filauer Swing Phase Lock System
Becaker Orthopedic UTX Swing KAFO
Becaker ORthopedic E-Knee (Broader application, patients with higher level of disability)
Ultraflex Systems Inc. Ultra Safe Step (Stroke Patients)
Anterior/Posterior Subluxation of knee
Motion controlled with KO having good purchase of proximal and distal to knee with sufficient lever arms and contact through soft tissue to stabilize the knee
Generation II
Don Joy
Osgood-Schlatter’s Disease
Pain can be relieved with infrapatellar strap to apply pressure at tibial tuberosity
Reduce motion and control tracking of patella as knee flexes and extends
Patellar stabilization knee sleeve also worn to decreased symptoms caused by patellofemoral conditions
Compartment Pain
Medial or lateral compartment pain managed in KAFO or possibly Ko
Applies varus or valgus force depending upon diseased compartment
Suspension of KO not always possible
Patellar Subluxation
Commonly controlled with neoprene or elastic knee sleeve having cut out for patella, sewn in buttresses that maintain patella in normal tracking position
