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Prosthetics&Orthotics > L3: KAFOs > Flashcards

L3: KAFOs Flashcards

1
Q

KAFOs

Things to consider…

A
  • 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**
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2
Q

KAFOs

Indications:

A
  • Excessive motion @ knee in stance NOT effectively controlled by just AFO
    • ballistic hyperEXT
    • uncontrolled knee flex (buckling) during wt acceptance
    • excess vaRus/valGus
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3
Q

KAFOs

Guidelines:

A
  • Cannot assess knee as isolated entity!
  • Proper align/function of knee→ result of poor hip and/or ankle align/strength
  • 3 Functions KAFO:
    1. protect jt it crosses
    2. structural integrity
    3. inc function
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4
Q

KAFOs

Stability vs Mobility

A
  • 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
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5
Q

KAFOs

2 types:

A
  1. Conventional (metal+leather)→ old school
  2. Molded thermoplastic
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6
Q

“Conventional” think….

A

Metal + leather

Old skoooool

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7
Q

Conventional AFOs

Three-point force system

A
  • 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
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8
Q

Molded Thermo. KAFO

Force system

A

see pics

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9
Q

Conventional KAFOs

Advantages vs. Disadvantages

A
  • 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*
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10
Q

Conventional KAFOs

Indications:

A
  • Need max strength/durability
  • Obese
  • Flucuating/uncntrld edema
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11
Q

Conventional KAFOs

CONTRAindications:

A
  • Energy expenditure issues (it’s heavy)
  • When control in transv or frontal plane important
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12
Q

Thermoplastic KAFOs

The deets

A
  • 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
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13
Q

Thermoplastic KAFOs

Fit, counterforces, design

A
  • Intimate fit= larger interface w/ limb= control/force dispersion
  • A/P Counterforces→ control sag. plane
  • Total contact design→ transv/frontal plane control
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14
Q

Thermoplastic KAFOs

Advantages vs Disadvantages

A
  • Advantages
    • lt. weight, interchangeability w/ shoes, more cosmetic*
  • Disadvantages
    • hot to wear
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15
Q

Thermoplastic KAFOs

Indications

A
  • MAX control needed
  • When energy expenditure makes wt of orthotic an issue
  • When control in transverse plane needed***
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16
Q

Thermoplastic KAFOs

CONTRAindications

A
  • Intimate fit diff w/ obesity
  • Intimate fit compromised w/ uncontrolled/fluctuating edema
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17
Q

KAFOs

Ankle Control Options

A
  • 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!!!!
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18
Q

KAFOs

Ankle Control

If Immobilization is desired @ knee…

A
  • 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
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19
Q

Primary reason for rx KAFO vs AFO

A

Poor knee motor control/strength

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20
Q

KAFOs

Knee Control→ Single axis (AKA: straight knee joint w/out drop lock or “free knee”)

Permits what to prevent/provides what?

A
  • Permits unrestrict. flexion and FULL Ext in sag. plane
    • Prevents→ hyperEXT
    • Provides→ medio-lateral stability
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21
Q

KAFOs

Knee Control→ Single axis

Indications

A
  • 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***
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22
Q

KAFOs

Knee Control→ Single axis locking knee

What is it? Indications?

A
  • Single axis knee locked t/o gait
  • Indicated→ pts unable to control knee in Stance
  • **NOTE: NEGATIVE effects on clearance and swing phase
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23
Q

KAFOs-Knee Control

Offset Knee Jt

Key feature+ Axis of rotation where (aka where is it offset?)

A
  • Key Feature: POSTERIOR alignment of the knee axis
  • Bench alignment places AOR posterior to anatomical knee
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24
Q

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)?

A
  • 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
25
Q

KAFOs-Knee Control

Offset Knee Joint

IC→MSt

*pay attention to KAFO axis of rotation (blue dot)

A

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!!!!!

26
Q

KAFOs-Knee Control

Offset Knee Joint

Explain what happens as body progresses forward

A
  • 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!)
27
Q

KAFOs-Knee Control

Offset knee joint

Appropriate for?

A
  • Pts w/ limted knee control:
    • LMNL (Lower Motor Neuron Lesions)
      • Polio
      • Spina Bifida
      • Lower T/S SCIs
28
Q

This KAFO for knee control is designed for those w/ knee flexion contractures (stuck in knee flex) who can NOT attain full knee EXT

A

Think…Dial Lock knee jt

Variable position knee joint (Dial Lock)

29
Q

Dial Lock think…..

A

Knee flexion contractures!!!

30
Q

KAFOs- Knee Control

Variable Position Knee Joint (DIAL LOCK)

What is going on w/ a knee that is stuck in flexion?

A
  • 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.
31
Q

KAFOs-Knee Control

Variable position knee joint (DIAL LOCK*)

How is it set and why?

A
  • 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
32
Q

Various types of KAFOs knee joints

A

see pics

33
Q

This KAFO mimics a regular knee VERY closely

*similar to wt. activated prosth. knee

A

Stance and Swing Phase Influencing joints

Think “quad weakness” ******

34
Q

KAFOs-Knee Control

Stance and Swing Phase Influencing Joints

A
  • 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
35
Q

Stance and Swing Phase Influencing Joints

in a nutshell….

A

Locks when you’re about to hit IC (first rocker) and Unlocks when you’re about to do Heel Off (start of third rocker)

36
Q

KAFOs-Knee Control

Stance and Swing Phase Influencing Joints

BENEFITS

A
  • 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
37
Q

GOLD STANDARD FOR KNEE ORTHOTICS

A

Stance and Swing Phase Influencing Joints

38
Q

Stance and Swing Phase Influencing Joints

GOLD STANDARD FOR…

A

KNEE JOINT ORTHOTICS

39
Q

Stance and Swing Phase Influencing Joints

In essence, what is happening?

A
  • 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
40
Q

KAFOs-Knee Control

Stance control orthotics

A
  • 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.
41
Q

KAFOs and knee control

Depends on 3 things:

A
  1. Pts ability to understand timing of gait
  2. Environment
  3. Nature of task
42
Q

Orthotic knee can be set in 1 of 3 modes:

A
  1. Auto stance control→ locks in certain pos’s
  2. Unlocked
  3. Always locked
43
Q

KAFOs-Knee Control

LOOK THESE UP!!!

A
  • UTX Swing and free walk
  • Swing phase lock
  • Load response joint
  • G knee
  • E knee
44
Q

KAFOs-Locking Mechanisms

Ring or Drop Lock

*you’ve seen this

What is it and who NOT to use w/

A
  • 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
45
Q

KAFO-Locking Mechanisms

Bail Lock

“the one where you have to back up into the table/chair to unlock the knee”

A
  • 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
46
Q

Designed for pts w/ paraplegia w/out hip control

A

Craig-Scott KAFO

47
Q

Special KAFO designs:

Craig-Scott

A
  • For→ Paraplegia w/out hip control
  • MIN bracing, MAX stability
  • Single thigh (below isch tube) and calf band (below knee)
48
Q

Special KAFO desigs

Craig-Scott

How it works

A
  • 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
49
Q

Special KAFO designs

Craig-Scott

Indicated for?

A
  • Good body awareness and proprio
  • Swing thru pattern for loco.
  • Also effective→ DMD, spina bifida peds
50
Q

KAFO w/ NO STABILITY

A

Single axis UNlocked

51
Q

KAFO w/ MAX stability

A

Single axis LOCKED

52
Q

OFFSET knee design and GRF

A

keeps GRF anterior to knee => inc stability in knee EXT

53
Q

This KAFO accommodates Crouch Gait

A

Variable position locked

*DIAL LOCK

54
Q

Indications vs Contraindications for Orthotic Knee Joint Designs

Chart

A

See chart

55
Q

Single Axis UNlocked

Indicated

A
  • Control genu valgum/varum
56
Q

Single Axis LOCKED

Indicated

A
  • 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
57
Q

Offset UNlocked

Indicated

A
  • Stab. of flail knee w/ knee EXT moment and free knee joint motion
  • control genu recurvatum
  • control genu varum/valgum
58
Q

Offset LOCKED

indicated

A
  • 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
59
Q

Variable Position Locked (DIAL LOCK)

indicated

A
  • Reduction of knee flex contracture

Prosthetics&Orthotics (19 decks)

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