L3: KAFOs Flashcards
KAFOs
Things to consider…
- Pts goal/Lvl of function
- Consistent use/acceptance depend on how well orthosis meets needs/goals
-
Consider Dx!
- improve? get worse? stay same?
- MS, GBS**
- improve? get worse? stay same?
KAFOs
Indications:
- Excessive motion @ knee in stance NOT effectively controlled by just AFO
- ballistic hyperEXT
- uncontrolled knee flex (buckling) during wt acceptance
- excess vaRus/valGus
KAFOs
Guidelines:
- Cannot assess knee as isolated entity!
- Proper align/function of knee→ result of poor hip and/or ankle align/strength
-
3 Functions KAFO:
- protect jt it crosses
- structural integrity
- inc function
KAFOs
Stability vs Mobility
- Inverse relationship bw functionality (mobility) vs stability***
- improved function not always equal to “normal”
- Goals of stability/protection==> improved function compared to gait w/out orthotic
KAFOs
2 types:
- Conventional (metal+leather)→ old school
- Molded thermoplastic
“Conventional” think….
Metal + leather
Old skoooool
Conventional AFOs
Three-point force system
-
3-point system:
-
Two anteriorly directed forces:
- PROX=> posterior thigh band
- DIST=> shoe and posterior calf band
-
One posteriorly directed force:
- Anterior knee pad OR anterior thigh and calf strap
-
Two anteriorly directed forces:
Molded Thermo. KAFO
Force system
see pics
Conventional KAFOs
Advantages vs. Disadvantages
-
Advantages
- Strong, durable, easy adjust
-
Disadvantages
- heavy, must attach to shoe, less cosmetic, fewer contact pts reduce control (hard to control varus/valgus stress)
- ALL REASONS THEY WON’T WEAR IT*
- heavy, must attach to shoe, less cosmetic, fewer contact pts reduce control (hard to control varus/valgus stress)
Conventional KAFOs
Indications:
- Need max strength/durability
- Obese
- Flucuating/uncntrld edema
Conventional KAFOs
CONTRAindications:
- Energy expenditure issues (it’s heavy)
- When control in transv or frontal plane important
Thermoplastic KAFOs
The deets
- Custom made→ intimate fit
- Distal shell→ foot, ankle, lower leg (solid or artic. ankle)
- Prox shell→ thigh- greater troch to prox. fem condyles
- Metal knee jts + sidebars→ connect dist + prox shell
Thermoplastic KAFOs
Fit, counterforces, design
- Intimate fit= larger interface w/ limb= control/force dispersion
- A/P Counterforces→ control sag. plane
- Total contact design→ transv/frontal plane control
Thermoplastic KAFOs
Advantages vs Disadvantages
-
Advantages
- lt. weight, interchangeability w/ shoes, more cosmetic*
-
Disadvantages
- hot to wear
Thermoplastic KAFOs
Indications
- MAX control needed
- When energy expenditure makes wt of orthotic an issue
- When control in transverse plane needed***
Thermoplastic KAFOs
CONTRAindications
- Intimate fit diff w/ obesity
- Intimate fit compromised w/ uncontrolled/fluctuating edema
KAFOs
Ankle Control Options
- SAME AS IN AFOs→ bc still an “ankle” component…. Knee Ankle Foot Orthosis
- Ankle config + GRFs influence knee function and forward progress. during gait*** KNOW THIS!!!!
KAFOs
Ankle Control
If Immobilization is desired @ knee…
- You want MORE MOTION @ ankle joint→ improves function by allowing tibia to easily advance over fixed foot
-
NOT in pts best interest to have BOTH ankle/knee locked
- IF both locked→ CPO adds EXT shoe mods to facil. all three rockers
Primary reason for rx KAFO vs AFO
Poor knee motor control/strength
KAFOs
Knee Control→ Single axis (AKA: straight knee joint w/out drop lock or “free knee”)
Permits what to prevent/provides what?
- Permits unrestrict. flexion and FULL Ext in sag. plane
- Prevents→ hyperEXT
- Provides→ medio-lateral stability
KAFOs
Knee Control→ Single axis
Indications
- M/L jts placed bw medial ADD tubercle and medial tib plateau
- Indicated for→ pts w/ enough mm function to ensure knee stability early in Stance BUT may move into recurvatum later in stance OR sig. structural (M/L, ACL) instability***
KAFOs
Knee Control→ Single axis locking knee
What is it? Indications?
- Single axis knee locked t/o gait
- Indicated→ pts unable to control knee in Stance
- **NOTE: NEGATIVE effects on clearance and swing phase
KAFOs-Knee Control
Offset Knee Jt
Key feature+ Axis of rotation where (aka where is it offset?)
- Key Feature: POSTERIOR alignment of the knee axis
- Bench alignment places AOR posterior to anatomical knee
KAFOs-Knee Control
Offset Knee Joint
The bench alignment for an offset knee joint places the axis of rotation posterior to anatomical knee
What happens as a result of this in early stance (LR)?
- GRF passes closer to the center of the axis of the orthotic joint→ REDUCES magnitude of the external FLEX moment that is acting to flex the limb
KAFOs-Knee Control
Offset Knee Joint
IC→MSt
*pay attention to KAFO axis of rotation (blue dot)
Bc of POSTERIOR alignment→ LESS flexion moment on knee jt.
As body progresses forward (into MSt, when knee EXT is happening)→ the GRF moves MORE QUICKLY ahead of the orthotic joint= mech. extensor force
see pics
KNOW THESE PICTURES AND EXPLAIN THEM!!!!!
KAFOs-Knee Control
Offset Knee Joint
Explain what happens as body progresses forward
- As body progresses forward the GRF more quickly moves ahead of the orthotic joint==> mechanical EXTENSOR force that augments stance phase stability
- drop locks can be added for long term standing (you know what these are!)
KAFOs-Knee Control
Offset knee joint
Appropriate for?
- Pts w/ limted knee control:
- LMNL (Lower Motor Neuron Lesions)
- Polio
- Spina Bifida
- Lower T/S SCIs
- LMNL (Lower Motor Neuron Lesions)
This KAFO for knee control is designed for those w/ knee flexion contractures (stuck in knee flex) who can NOT attain full knee EXT
Think…Dial Lock knee jt
Variable position knee joint (Dial Lock)
Dial Lock think…..
Knee flexion contractures!!!
KAFOs- Knee Control
Variable Position Knee Joint (DIAL LOCK)
What is going on w/ a knee that is stuck in flexion?
- Knee that is stuck in flexion (i.e. crouched gait)
- GRF remains posterior to anatomical knee
- → Diff for pt w/ weakness or decd motor control to maint. necessary counteractive force for stance stab.
- GRF remains posterior to anatomical knee
KAFOs-Knee Control
Variable position knee joint (DIAL LOCK*)
How is it set and why?
- Locked in most EXTd pos. possible → External mechanical stability
- serrated disc→ 1 serration=6degs
- *may also provide low load prolonged stretch→ decs severity of contracture
Various types of KAFOs knee joints
see pics
This KAFO mimics a regular knee VERY closely
*similar to wt. activated prosth. knee
Stance and Swing Phase Influencing joints
Think “quad weakness” ******
KAFOs-Knee Control
Stance and Swing Phase Influencing Joints
-
Specifically for→ QUAD WEAKNESS
- Stance control W/OUT being locked in swing
- Allows→ knee to lock @ a point approximating IC (first rocker) and unlock @ heel off (beginning third rocker)
- **More natural gait pattern
Stance and Swing Phase Influencing Joints
in a nutshell….
Locks when you’re about to hit IC (first rocker) and Unlocks when you’re about to do Heel Off (start of third rocker)
KAFOs-Knee Control
Stance and Swing Phase Influencing Joints
BENEFITS
-
Unlocking knee @ onset of 3rd rocker→ LESS compensatory mechs reqd to clear foot that would occur w/ a locked knee
- circumduction, hip hike
- LESS enrgy expend. and low back stress
GOLD STANDARD FOR KNEE ORTHOTICS
Stance and Swing Phase Influencing Joints
Stance and Swing Phase Influencing Joints
GOLD STANDARD FOR…
KNEE JOINT ORTHOTICS
Stance and Swing Phase Influencing Joints
In essence, what is happening?
- Dynamic loads trigger locking and unlocking of knee joint depending on where in gait cycle limb is
- LOCKING→ IC, MSt,
- UNLOCKING→ LR, TST/PSW, SWING
KAFOs-Knee Control
Stance control orthotics
-
Internal cams→ lock knee from upward press. on push rod
- IC→Mst
- Cam unloads in late stance (TSt-PSw)→ lock disengages== knee flexion for limb clear.
KAFOs and knee control
Depends on 3 things:
- Pts ability to understand timing of gait
- Environment
- Nature of task
Orthotic knee can be set in 1 of 3 modes:
- Auto stance control→ locks in certain pos’s
- Unlocked
- Always locked
KAFOs-Knee Control
LOOK THESE UP!!!
- UTX Swing and free walk
- Swing phase lock
- Load response joint
- G knee
- E knee
KAFOs-Locking Mechanisms
Ring or Drop Lock
*you’ve seen this
What is it and who NOT to use w/
- Standard lock captures m and f portions of upright preventing unwanted flex or hyperEXT
- Need FULL ext before lock/unlock
-
NOT INDICATED FOR:
- limtd hand function
- sig LE spasticity
- diff balancing w/ one AD
KAFO-Locking Mechanisms
Bail Lock
“the one where you have to back up into the table/chair to unlock the knee”
- Lever system connects Med/Lat locks
- back up to seating surface
- Quad/glute strength to control descent OR use UEs
-
*USE:
- Paraplegic pts who must maint. B/L UE support on crutches while standing
Designed for pts w/ paraplegia w/out hip control
Craig-Scott KAFO
Special KAFO designs:
Craig-Scott
- For→ Paraplegia w/out hip control
- MIN bracing, MAX stability
- Single thigh (below isch tube) and calf band (below knee)
Special KAFO desigs
Craig-Scott
How it works
- Has DF assist and offset locking knee jt
- Teach to hang in “Y” ligs of ant. hip w/ hyperlordosis @ L/S
- → induces GRF falls just ant to knee (ext mom.) and post to hip (ext mom.)
- Result→ No mm control reqd
Special KAFO designs
Craig-Scott
Indicated for?
- Good body awareness and proprio
- Swing thru pattern for loco.
- Also effective→ DMD, spina bifida peds
KAFO w/ NO STABILITY
Single axis UNlocked
KAFO w/ MAX stability
Single axis LOCKED
OFFSET knee design and GRF
keeps GRF anterior to knee => inc stability in knee EXT
This KAFO accommodates Crouch Gait
Variable position locked
*DIAL LOCK
Indications vs Contraindications for Orthotic Knee Joint Designs
Chart
See chart
Single Axis UNlocked
Indicated
- Control genu valgum/varum
Single Axis LOCKED
Indicated
- Stab. of flail knee w/out use of knee EXT moment and free knee jt motion
- control genu recurvatum→ IF orthosis only locked during amb.
- control genu valgum/varum
Offset UNlocked
Indicated
- Stab. of flail knee w/ knee EXT moment and free knee joint motion
- control genu recurvatum
- control genu varum/valgum
Offset LOCKED
indicated
- stab of flail knee w/OUT use of knee EXT moment and free knee jt motion
- control genu recurvatum→ when indiv will lock knee intermitt.
- control genu varum/valgum
Variable Position Locked (DIAL LOCK)
indicated
- Reduction of knee flex contracture
