Lower Extremity Prosthetic Components Flashcards
1
Q
The basic components to prosthetics
A
- Custom socket
- Pylon
- Knee (for TF amputation)
- Foot
- Suspension
2
Q
Contemporary sockets (total contact) for TT amputees
A
- Not appropriate for everyone
- Distribute load equally
Proper fitting sockets do NOT cause pain
3
Q
Patellar tendon-bearing socket
A
- Indentation below the patella that allows the patellar ligament to serve as a major WB surface
- Posterior wall applies counterforce
4
Q
Patellar tendon bearing socket-Supra condylar
A
- Socket comes above the condyles of femur
- Pinching provides some suspension and provides medial-lateral stability
- Will see this when the residual limb is short
5
Q
Places on PTB that CAN take pressure
A
- Patellar tendon
- Either side of tibia
- Fibula
6
Q
Places on PTB that CANNOT take pressure
A
- Fibular head
- Anterior tibia where beveled
- Crest of tibia
- End of fibula
- Popliteal space
7
Q
Elastic sleeve
A
Primary or secondary means of suspension
8
Q
Polyethylene foam
A
Older method of suspension
- Easy to add onto for final size of limb
9
Q
Silicone gel liners
A
- Newer method of suspension
- Comfortable, perspiration
- Metal pin (shuttle lock) wont pull out from socket
- Lanyard system (cable)
10
Q
Vacuum assisted suspension system
A
- Suction sockets w/ one-way valves
- Regulates residual limb volume changes
- Improves circulation
11
Q
Supracondylar cuff
A
- Older methods of suspension for TT
- Used for low level ambulation
- Allows for normal knee motion
- Easy to don
- Inexpensive
- Does not eliminate all pistoning
- Band goes around waist
12
Q
Supracondylar-suprapatellar
A
- Older method of suspension for TT
- Improved mediolateral stability
- Better suspension on short residual limbs
- Limited kneeling
- Works poorly with large thighs
13
Q
Waist belts-thigh corsets
A
- Older suspension method for TT
- Provides additional surface for WB
- Uneven suspension
- Difficult to don-doff
- Atrophy of thigh
14
Q
Medicare function levels
A
K0
K1
K2
K3
K4
15
Q
K0
A
No potential ambulation in the reasonable near future (not forever)
16
Q
K1
A
Level surface, fixed cadence, typically household ambulators about 20-30 ft
17
Q
K2
A
Community ambulator, transverse low level barriers ie. Onto/off curb, few stairs, single speed difficult to walk on uneven surfaces
18
Q
K3
A
Variable cadence, transverse most barriers, vocational (work-related) and recreational activity beyond simple locomotion (can walk on uneven surfaces)
19
Q
K4
A
High impact, stress, energy levels (sports, farmer, different environment)
- Medicare may pay for services if its vocational purposes, not for sport
20
Q
Pylons
A
- Connects socket to foot
- May have shock absorption
- May have torque absorption
- May have issues with medial/lateral & anterior/posterior alignment
21
Q
The five feet
A
- SACH (single axis cushioned heel)
- Single axis
- Multi axis
- Dynamic response
- Multi axis-dynamic response
22
Q
SACH foot
A
- Internal wood or plastic heel surrounded by a foam shell
- No moving parts
- Good shock absorption at heel strike
- Used for K1 & K2 ambulators
23
Q
Single axis
A
- Allows for some PF & DF
- Increases knee stability
- Ability to walk up/down inclines
- Bumpers need to be maintained
- Used for K1 & K2 ambulators
24
Q
Multi axis
A
- Allows for some PF, DF inversion & eversion
- Increases stability on uneven surfaces
- Ability to walk up/down inclines
- Bumpers need to be maintained
- Used for K2 & K3 ambulators
25
Dynamic response
- Provides energy return (energy stored during foot contact)
- Most common type of foot
- Helps to normalize time spent on sound and amputee sides (50/50)
- Used for K3 & K4 ambulators
26
Otto Bock dynamic response feet
Ossur flex-run used for K4 ambulators, often athletes
27
Sockets for TF amputees
- Quadrilateral
- Ischial containment
- Flexible
- Dynamic transfemoral
28
Quadrilateral socket
- Ischial tuberosity sits on the posterior rim
- Posterior wall is major WB surface
- Contoured for hamstring
- Anterior wall above posterior about 5 cm
- Medial and lateral wall similar in height
29
Ischial containment socket
- Improved control in stance, greater WB, smoother swing (more circular in shape)
- Ischium and ascending ramus are enclosed in socket
- Narrow media lateral dimension to improve rotational stability
- Lateral wall is much higher than medial wall
30
Dynamic transfemoral socket
- More common
- Malleable-flexible thermoplastic socket
- Supported by semi-rigid frame
- Multiple cut-outs allowing for movement of limb in socket
- Suction is the primary suspension mechanism
31
Suction for TF suspension
- Allow for full freedom of hip motion
- Good proprioceptive feedback through its intimate fit
- Difficult to obtain good fit, suction may be lost through perspiration, potential for skin shear, abrasions, and irritation
- Requires good balance & coordination for donning
32
Silesian bandage for TF suspension
- Lightweight additional suspension
- Provides some rotational control
- Difficult to keep clean unless it is detachable
- Can irritate the waist
33
Total elastic suspension for TF amputees
- Provides excellent suspension
- Adjusts to size of individual
- Generally comfortable
- Adds less weight than the pelvic belt
- Retains body heat which may lead to skin irritations and discomfort
- Wears out easily
- Difficult to keep clean
34
Pelvic belt for TF suspension
- Provides for rotational control, easy to don
- Provides mediolateral pelvic stability
- Adds weight to the prosthesis
- Usually not very comfortable
-Highest level of support used for K1 ambulators
35
Knees in prosthetics
1. Single axis constant friction
2. Polycentric (four bars)
3. Fluid controlled
4. Computerized
36
Single-axis constant friction
- Light-weight, durable, less expensive
- Often used on temporary prostheses
- Often used on children’s (lighter)
- May have friction lock (so knee won’t flex during inappropriate times)
- Used for K1 ambulators
37
Polycentric knees (four bar)
- Good for active users
- Gait stability w/o cost of computerized knee
- Stable in early stance
- Flexes easily in pre-swing
- Weight line lies anterior to instant axis of knee rotation longer than single axis
- Add weight to prosthesis
- Can get wet
- Used for K1-2 ambulators
38
Fluid controlled knees
- Allow variable speed gait
- Pneumatic or hydraulic
- Increase or decrease swing phase resistance as users vary walking speed
- More natural gait
- Add weight and cost to prosthesis
- Maintenance requires
- Used for K3 ambulators (variable gait speed)
39
Microprocessor controlled knees (computerized knee)
C (Canadian) leg by Otto Bock is most common
Genium by Otto Bock allows for pivot on leg
Ossur Rheo Knee 3 weatherproof used for K4 ambulators
40
Hydraulic knee system
Strain gauges in the shin tube & the angle sensor in the knee provide angle and moment info to the computer.
- Info is processed by the microprocessor & compares the info with known gait data & changes the hydraulic valves to provide stance phase stability & cadence responsive swing phase control
41
Stability in hydraulic knee system
- Not necessary for knee axis to be aligned as far posterior as it is in other knee joints to provide stability
- Stability provided by the electronically controlled hydraulic knee
- Person does not need to keep the line of gravity behind the joint to maintain knee lock
42
Programming hydraulic knee system
- Prosthetist can change the parameters of the knee and sent the computer microprocessor
- Parameters: toe load, heel load, stance flexion/extension, swing extension dampening, initial swing flexion dampening, knee angle threshold, dynamic factor
43
Osseointegration
- Biocompatible metal devices inserted into residual bone to integrate and attach to external prosthesis
- Eliminates need for socket prostheses & problems that may accompany their use
- Prosthetic leg attached to implant between 3-10 weeks post-op depending on bone quality
- Increase WB over several weeks starting at about 20 pounds
- Partial WB for an additional 6 weeks
- Allows for more natural alignment & more efficient gait
