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Prosthetic Study > Transfemoral > Flashcards

Transfemoral Flashcards

1
Q

Advantages of Microprocessor Control Knee (6)

A
  • increased safely and stumble recovery
  • smoother, more natural gait
  • ability to descend stairs/ramps easier
  • less energy expenditure
  • decreased cognitive load
  • automatic adjustments for variable cadence and charging conditions
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2
Q

Disadvantages of Microprocessor Control Knee (5)

A
  • increased cost
  • increased weight
  • durability/water resistance (not ideal for high activity)
  • require charging and upkeep
  • cosmesis (charging ports)
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3
Q

Why Pre-flex a TF socket

A
  • extension reserve
  • length/tension ratio of hip extensors
  • expose IT
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4
Q

Silesian Belt Attachment

A
  • anteriorly; at the IT level, at the intersection of the medial and middle thirds of the socket
  • wraps around the contralateral pelvis between the illiac crest and greater trochanter
  • laterally; 1cm posterior and proximal to the GT
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5
Q

TF Suspension Methods (5)

A
  • silesian belt
  • tes belt
  • hip joint and pelvic band with belt
  • traditional suction
  • liner with pin, suction ring, lanyard, other
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6
Q

Knee Categories (7)

A
  • manual locking
  • stance control (safety)
  • constant friction (SA)
  • polycentric
  • fluid controlled
  • hybrid
  • microprocessor
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7
Q

Bench Alignment for TF Prosthesis Frontal

A

Alignment reference line passes:

  • through center of socket with appropriate ab/adduction angle (about 5-10 degrees)
  • through center of knee with axis parallel to the ground
  • through center of heel
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8
Q

Bench Alignment of TF Prosthesis Sagittal

A

Alignment reference line passes:

  • through center of socket with appropriate flexion (HFC + 5-10 degrees)
  • ~1cm anterior to knee center
  • through the center of the weight bearing surface of the foot
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9
Q

Bench Alignment of TF in Transverse Plane

A
  • Socket in LOP
  • Knee axis perpendicular to LOP (or slightly externally rotated)
  • 5-7 degree toe out
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10
Q

Quad (2) vs. Ischial Containment (4)

A

Quad

  • narrow A/P
  • square shape brim

Ischial Containment

  • narrow M/L
  • longer frontal plane force couple due to boney lock
  • better for short limbs, weak abductors and bilateral TF’s
  • lower anterior trimline
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11
Q

Transfemoral Surgical Goals (6)

A
  • maximize femoral length
  • stabilize muscle
  • avoid contractures
  • protect cut end of bone
  • maximize soft tissue/skin coverage
  • retain good sensation
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12
Q

Measurements to Take During TF Casting/Assess

A
  • IT-AL
  • IT-GT
  • IT - Rec Fem
  • IT - distal end
  • Femoral Length
  • IT-Floor
  • KC - Floor
  • Circumferences in intervals
  • cosmetic circumferences
  • foot lengths and heel heights
  • any needed for suspension method
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13
Q

Lateral trunk bending

A

Amputee leans towards amputated side when prosthesis is in stance phase

CAUSES

  • Weak abductors
  • Insufficient support by the lateral socket wall
  • Pain or Discomfort lateral distal femur
  • Abducted socket- insufficient adduction
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14
Q

Circumduction

A

Prosthesis follows lateral curved line as it swings

CAUSES

  • Lack of confidence in knee security, patient doesn’t want knee to bend
  • Excessive friction or extension resistance
  • Poor suspension- resulting in pistoning
  • Socket fit- ischial tuberosity of above shelf
  • Prosthesis is too long
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15
Q

Medial Whip/Lateral Whip

A

Medial Whip
- At toe-off the heel of the prosthetic foot moves medially
Lateral Whip
- At toe-off the heel of the prosthetic foot moves laterally

CAUSES

  • Improper alignment of the knee axis in the transverse plane
  • Improperly contoured socket - not accommodating muscle contraction
  • Poor muscle tone
  • Improper attachment of silesian belt
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16
Q

Exaggerated Lordosis

A

Amputee trunk leans posteriorly when the prosthesis is in stance phase

CAUSES

  • Insufficient socket preflexion
  • Hip flexion contracture
  • Insufficient support from prosthetic socket
  • Weak hip extensors that aid in knee stability
  • Inadequate core strength
17
Q

Vaulting

A

Amputee raises his whole body via early and excessive plantarflexion of the sound foot

CAUSES
Prosthesis too long
Knee friction too high
More time to bring leg through “Terry Fox”

18
Q

Excessive Heel Rise

A

Prosthetic heel rises higher than sound heel during early swing

Not enough friction in knee

19
Q

Relevant Muscles Anterior

A

Knee Extensors
- Vastus Medius + Lateralis

Hip Flexors

  • Rectus Femoris
  • Sartorius

Hip Adductors

  • Adductor Magnus
  • Adductor Longus
  • Adductor Brevis
  • Gracilis
  • Pectineus
20
Q

Relevant Muscles Posterior/Lateral

A

Hip Extensors

  • Gluteus Maximus
  • Semimembarnosus
  • Semitendinosus
  • Biceps Femoris

Hip Abductors

  • Gluteus Medius
  • Gluteus Minimus
21
Q

Femoral Triangle “Scarpus”

A

Borders

  • Medial - Adductor Longus
  • Lateral - Sartorius
  • Proximal - Inguinal Ligament

Floor

  • Illiopsoas
  • Pectineus

-Area of compression for A-P

22
Q

Surgery - General

A
  • Muscles cut
  • Bone Sectioned/Rounded
  • Myodesis (muscle to bone)
  • Myoplasty (muscle to muscle)
  • Adductor Magnus wrapped over distal Femur, fixed laterally under tension, acts to resist ABduction, sewn on in adduction, keeps ABductors tight
23
Q

Common Contracture

A

Shorter limb means greater chance for aBduction and Flexion contracture

24
Q

Alignment to help out short residuum

A

Laterally offset foot (help out hip abductors)

Anteriorly displace socket (activate knee easier)

25
Q

Typical Contractures seen in Transfemorals

A

Hip Flexion

Hip Abduction

Attachment point of hip extensors and adductors are more distal on the femur or cross the knee joint, therefore flexion/abduction bias typically exists after amputation surgery

26
Q

Locking Knee Indications

A

Weak Hip Extensors, Poor Control of Hip

Good for Transfers

Fixed Cadence

Cognitive Issues

Knee of last resort (ultimate stability)

EXAMPLES: Ottobock 3R40, 3R33

27
Q

Locking Knee Effects on Gait

A

Weight bearing stability - knee locked

Knee has No Stance Flexion, need to provide shock absorption through foot

Limb advancement - no knee flexion, need compensatory movements to clear prosthesis in swing (hip hiking, vaulting, circumduction)

If toe clearance an issue, may consider shortening prosthesis

Poor efficiency, increased energy expenditure, greater displacement of Centre of Mass

28
Q

Characteristics of Single Axis Knees

A

Stance control- Through Alignment/Muscular

Swing control - Swing Flexion - constant friction
- Swing Extension- spring assist

29
Q

Single Axis, Constant Friction Indications

A
  • Fixed Cadence
  • Adequate Hip Extensors (strength, range, control)
  • Durable
  • Inexpensive

EXAMPLE: Ottobock 3R17, 3R22

30
Q

Single Axis, Constant Friction Effects on Gait

A
  • weight bearing stability - muscular, knee alignment, soft heel preferable, mimics plantarflexion, moves GRF ahead of knee more rapidly
  • No stance flexion, need to get shock absorption through foot
  • Swing- limb advancement, toe clearance, preparation for stance - all dependent on balance between Constant Friction / Extension Assist
31
Q

Weight Activated Braking Knee Indications

A

Fixed Cadence

Poor but adequate hip extensors

Need for Added Stability

NEVER USE FOR BILATERAL

32
Q

Weight Activated Braking Knee Characteristics

A

Single Axis

Stance control

  • weight activated, locked in extension when weight on it
  • also through alignment and muscular Swing control

Swing control

  • Flexion- constant friction
  • Extension - extension assist
33
Q

Weight Activated Braking Knee Effects on Gait

A

Weight bearing stability - Weight Activation along with Knee alignment, Muscular

No Stance Flexion, provide shock absorption at the foot

Positioning limb for swing -initiating knee flexion

  • foot selection (s/a vs dynamic response)
  • reduce stance sensitivity
  • unweight proshtesis
  • foot position (heel lever/toe lever)

Limb advancement, toe clearance, preparation for stance - balance between constant friction and extension assist

34
Q

Polycentric knee constant friciton, Indications

A
  • Fixed Cadence
  • Weaker Hip Extensors
  • Higher level of amputation (for short limb, provides more stability)
  • Long levels of amputation (sitting cosmesis)
  • HOWEVER, Increased weight of knee unit
35
Q

Polycentric Knee Characteristics

A

4-bar design

Stance control

  • Instantaneous centre of rotation (ICOR)
  • Constant friction

Swing control

  • Flexion - constant friction
  • Extension - extension assist (hydraulic)
36
Q

Polycentric Knee Effects on Gait

A

Weight bearing stability

  • knee alignment (ICOR)
  • muscular

No stance flexion, provide shock absorption at foot

Position limb for swing-initiating knee flexion

  • ICOR
  • Foot selection (s/a vs. dynamic response)
  • Foot position (heel lever/toe lever)

Limb advancement, toe clearance, preparation for stance - balance of constant friction and extension asssit

ADDITIONAL TOE CLEARANCE PROVIDED BY SLIDING MECHANISM

37
Q

Hydraulic Pneumatic Knee Indications

A
  • VARIABLE CADENCE
  • powerful swing control
  • adequate hip extensors and flexors
  • increased cost/weight
38
Q

When to use Hip Joint Pelvic Band

A
  • weak hip abductors
  • hip weakness
  • pain
  • hip OA
  • patient preference

Prosthetic Study (10 decks)

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