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
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)
3
Q
Why Pre-flex a TF socket
A
- extension reserve
- length/tension ratio of hip extensors
- expose IT
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
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
6
Q
Knee Categories (7)
A
- manual locking
- stance control (safety)
- constant friction (SA)
- polycentric
- fluid controlled
- hybrid
- microprocessor
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
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
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
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
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
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
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
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
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
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
Typical Contractures seen in Transfemorals
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
Locking Knee Indications
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
Locking Knee Effects on Gait
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
Characteristics of Single Axis Knees
Stance control- Through Alignment/Muscular
Swing control - Swing Flexion - constant friction
- Swing Extension- spring assist
29
Single Axis, Constant Friction Indications
- Fixed Cadence
- Adequate Hip Extensors (strength, range, control)
- Durable
- Inexpensive
EXAMPLE: Ottobock 3R17, 3R22
30
Single Axis, Constant Friction Effects on Gait
- 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
Weight Activated Braking Knee Indications
Fixed Cadence
Poor but adequate hip extensors
Need for Added Stability
NEVER USE FOR BILATERAL
32
Weight Activated Braking Knee Characteristics
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
Weight Activated Braking Knee Effects on Gait
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
Polycentric knee constant friciton, Indications
- 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
Polycentric Knee Characteristics
4-bar design
Stance control
- Instantaneous centre of rotation (ICOR)
- Constant friction
Swing control
- Flexion - constant friction
- Extension - extension assist (hydraulic)
36
Polycentric Knee Effects on Gait
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
Hydraulic Pneumatic Knee Indications
- VARIABLE CADENCE
- powerful swing control
- adequate hip extensors and flexors
- increased cost/weight
38
When to use Hip Joint Pelvic Band
- weak hip abductors
- hip weakness
- pain
- hip OA
- patient preference
