Orthoses Proximal to the Knee - Module 4

Indications for Conventional KAFO

• fluctuating edema - minimal points of contact

• skin sensitivity 

Conventional KAFO Facts

fabricated from measurements and tracing (no casting involved)

responds well to changes in leg volume

attached to shoe, each pair of shoes needs to be modified.

Conventional KAFO is made from

metal and leather

What is the patient population most likely to ask for a conventional style KAFO?

people who are already using this style of brace

Thermoplastic (PP, Co-Poly, HDPE) or Laminated KAFO Facts

custom molded, easier to clean than conventional, poor heat dispersion

Total contact =

improved anatomic control

What patient population is it important for them to be able to clean their device frequently?

incontinence

Poor heat dispersion associated with a thermoplastic or laminated KAFO is specifically bad for what patient population?

Multiple Sclerosis (MS)

Total contact is advantageous because you can ________ the force over a larger area. 

spread

Thermoplastic or Conventional style KAFO has more contact?

thermoplastic

Hybrid KAFO Facts

Combines the best features of both systems

ex. Thermoplastic distal section may control foot/ankle while leather top increases sitting comfort. Conventional distal section may accommodate edema while thermoplastic thigh provides more control.

You will most likely see volume change where when wearing a KAFO?

extremities (feet)

Double Upright Facts 

• most stable in all planes 

• necessary for axial loading

• recommended for locking knee joints 

• prevent knee buckling 

Single Upright Facts 

• small lightweight patients

• can use locking or non-locking joint

Single Upright is most useful in what pathology?

• useful in genu valgum - especially bilateral 

Why is single upright the most useful for Genu Valgum?

so that the patient does not have their medial knee joints hitting each other while they walk.

There is higher torque in double/single uprights?

single

Disadvantage of Internal Uprights

if you have to make any adjustments it is really hard to adjust without risking integrity of the device

T or F. When choosing a KAFO with internal uprights you have to do a check orthosis before final fabrication

true 

Advantage of Internal Uprights

looks great and doesn’t damage clothes as much

T or F Trimlines should include the joint head on an Internal Upright KAFO.

TRUE

The material strength increases/decreases upright strength in a laminated KAFO. 

increases 

Free Knee Joint Facts

• simple hinge 

• single axis

• small compact design

  • contoured joint head

Free knee joint is aligned with the __________

anatomical knee joint

Free Knee joint is very stable in _______ and ______ planes. 

frontal, transverse

Free Knee joint prevents

hyperextension and frontal plane motion

Polycentric Knee Joint Facts 

• mimics anatomic knee motion 

• less protrusion during flexion

Polycentric Knee joints are useful in treating

fractures or accomodating large ROM (sports)

How many articulations does a polycentric knee joint have?

2

T or F The articulations on a polycentric knee joint are not independent. 

TRUE

Disadvantage of a Polycentric Knee Joint?

cant reach full knee flexion because the 2 articulations of the joint impinge on each other. 

Scott-Craig KAFO Facts 

very robust

locked knee

anterior calf band 

reinforced stirrup

Scott-Craig is designed for

paraplegics

Scott-Craig weight line falls _____ to ankle and _______ to hip and knee

anterior, posterior

Sarmiento’s Principle

circumferentially wrapped, bivalve opening if needed

Sarmiento’s Principle is not applicable for what kind of fracture?

comminuted fractures 

Fracture Bracing Facts

• thermoplastic

• most often custom fit

• polycentric knee joints

• clamshell design

• free ankle

If the ____ of the bone that is fractured then the adjacent segment should be _______ .

third, immobilized or locked 

Weight Bearing Designs must have

solid ankle and double upright locking knee

The Quad brim weight bearing design is good for _____ patients.

muscular

What is the problem with adding an ischial ring?

this is a proximal ring made up of padding, this is usually very round and does not provide a flat spot for the ischium to sit on

Ischial containment weight bearing design provides improved 

comfort and control of fleshy limbs

Can you use a bical joint on a weight bearing design ?

yes, it provides a smoother gait but only if your patient can use this kind of joint

Is there any atrophy with weight bearing designs?

When using this orthosis we are more worried about locking their joints up.

This orthosis is for muscle weakness usually so we aren’t as concerned about this

Coronal Plane deformities 

• ligament laxity 

• osteoarthritis 

• ricketts

• paget’s disease

• blount’s disease 

What is the KAFO treatment if we are correcting in the coronal plane?

KAFO with a free knee and ankle joint 

To treat a coronal plane deformity make sure it is ______.  

flexible

Genu Varum is associated with 

LCL/Medial compartment 

Conventional for Genu Varum consists of

5 buckle knee pad that wraps around the medial upright and pulls medially

OR

Lateral knee pad mounted on the lateral upright and pushes medially.

Thermoplastic trimlines for Genu Varum

thigh - high medial and lower lateral

calf - high lateral 

How does the patient know how tight to pull their straps?

you make a line that they should pull to everytime they don the orthosis

Genu Valgum is associated with

MCL, lateral compartment

Conventional for Genu Valgum consists of

5 buckle knee pad that wraps around lateral upright and pulls laterally 

OR 

medial knee pad that is mounted on the medial upright and pushed laterally

Thermoplastic trimlines for Genu Valgum 

thigh - high lateral and lower medial 

calf - high medial 

Sagittal plane abnormalities are ____ to treat than coronal. 

more challenging 

Sagittal plane abnormalities

contractures caused by - injury, surgery, positioning

weakness caused by - polio, CVA, paralysis, spina bifida, PVD, neuropathy

neuromuscular caused by - CVA, MS, ALS, MD

A knee contracture <_____° required for ambulation.

30

How can you accommodate for contractures concerning the uprights?

pre-flexed uprights 

What kinds of knee joint locks can you use for contractures?

step lock, adjustable flexion/extension knee joint, Ultraflex joints, and Monodos

Step lock 

locks in 15° increments using a ratcheting system 

Adjustable flexion/extension knee joint

available in drop lock or lever lock with a 6° increments (also available with a 6 position flexion stop)

The pre-flexed portion of the Adjustable Flexion/Extension Knee joint is positioned _______.

distally

Ultraflex knee joint

uses concentric torsion mechanism to apply a stretch to a contracture 

is NOT for ambulation

bulky

Monodos knee joint

provides unidirectional joint motion and is bulky.

NOT for ambulation

What are the Extension Assist Knee Joints

G-knee

GXL - knee

Ultraflex 

Stance Flexion joint 

Load response joint.

Locks in full extension then allows up to 15° of attenuated motion.

Fully extended in swing. 

Free when unlocked. 

Stance Flexion knee joint allows up to ___° of attenuated motion.

15

Knee buckling management above the knee

• manually locking knee joint

• posterior offset joint

• stance control knee joint 

Trimlines for Knee-Buckling

Conventional use 4-Buckle knee pad

thigh - high posterior and low anterior

calf - high anterior (possibly molded shell)

Manually Locking knee joint (drop lock)

automatic lock via gravity and manual unlock.

can be used with ball retainers to prevent auto-lock.

Manual Locking knee joint is hard to unlock when ______.

loaded

Manually Locking knee joint (trigger lock, drop with lift loop)

• automatic lock 

• proximal release

• difficult to unlock under load

Contraindications for Trigger Lock, Drop with lift loop

spasticity and knee flexion contracture

Manually Locking knee joint (bail lock or spring loaded lever lock)

• one motion unlocks both joints 

• allows for hands free operation 

• great for UE impairment 

Disadvantage of Bail Lock or Spring Loaded Lever Lock

may inadvertently unlock 

Manually Locking knee joint (electronic lock)

• solenoid engages lock with an audible signal to patient 

• remote control fob 

• minimal UE strength required

• stance control version available 

T or F Electronic locks are super common.

false

Posterior Offset joint moves weight line

posterior

Contraindications for Posterior Offset Joint 

knee or hip flexion contractures and PF stop 

Use of _______ design enhances performance of posterior offset joint. 

weight bearing 

Stance Control Knees

Horton

UTX and Free Walk

E-Knee

Sensor Walk 

Stride 

C-Brace 

Gait Activated Stance Control Knees

Lock in full extension and have a biomechanical trigger to unlock, these are sensitive to gait variations using gyroscopes

Need to have an MMT = 3 hip flexion 

Weight Activated Stance Control Knees

sensor in foot plate triggers the device to lock

electronics are prone to environmental degradation

batteries make these options heavier than others

Disadvantages of weight activated stance control knees

electronics are prone to environmental degradation and batteries make these options heavier than others

bulkier and more expensive 

Ankle Activated Stance Control Knee 

Locked in full extension with dorsiflexion to a specified degree that unlocks the joint. 

Adequate ankle motion is REQUIRED. 

Cables that run through the device sense when to unlock and lock from PF/DF at the ankle. 

Contraindications for Ankle Activated Stance Control Knees 

s/p ankle fusion, OA, infection, quad weakness, knee buckling

Stance Control 4-Bar knee joint (ankle driven)

use of weight bearing design enhances performance

posterior cable disengages lock when pulled.

Contraindications for Stance Control 4-Bar Knee Joint 

knee or hip flexion contracture

Genu Recurvatum is often secondary to

quad weakness

All orthotic knee joint should have a built in ______° extension stop

180

Genu Recurvatum treatment

shallow distal thigh and calf bands

Posterior knee strap (criss-cross) // 4 Buckle Knee Pad on Posterior 

Trimlines

thigh - high anteriorly and low posteriorly 

calf - high posteriorly (cannot interfere with knee flexion to 105°)

Double or single upright provide the best control in the transverse plane?

double

_______ stiffness is critical to transverse plane alignment.

Torsional

A KO may be converted to KAFO to control rotation of orthosis on a ____ limb.

fleshy - lamination?

Radius of curvature for aluminum must exceed ___ times the thickness of the upright.

6

Radius of curvature for stainless steel must exceed ___ times the thickness of the upright.

1

Strength Factors - Materials

• patient weight

• activity level

• locking knee

• double upright vs single upright 

• material 

• material thickness 

• orthosis design (internal vs. external joints)

Does the shape of the end of the upright affect strength of the upright?

yes - square vs round

Upright dimensions (Becker) represent

Moment of Inertia (MOI)