Week 4 Flashcards
What are the two basic cable controls used in UE prosthetics?
Housing fair lead-split housing at the elbow
Bowden Cable-continuous housing across the elbow
Who is the housing fair lead primarily used for?
Transhumeral, elbow disarticulations and very short transradials.
What does the housing fair lead do?
Flexes the elbow when the elbow is unlocked
Flex elbow for a split socket design with residuum activated outside locks
To augment elbow flexion for split socket with step-up hinges.
What motions does the housing fair leads harness control?
Humeral flexion
Bi-scapular abduction and protraction
What is the Bowden Cable mostly used for?
Transradials
What are two aspects specific to the Bowden cable?
Continuous house across the elbow
Tension on the cable has no impact on the elbow flexion
What is the shoulder harness used for?
carrying heavy loads
patient’s who cannot tolerate the full axillary loop for actuation
What are three aspects of the bilateral figure 8 harness?
No axillary loop
The delto-pectoral suspension straps are connected to the cross point
An elastic cross strap is added to prevent upward migration
When is the figure 9 harness used?
For self suspending sockets like the muenster
What are two aspects specific to the figure 9 harness?
It does not used the delto-pectoral suspension strap
The cross bar attaches to the mid posterior proximal brim of the socket
Where is the crosspoint of the harness supposed to be?
Inferior to C7
Slightly towards the non-amputated side
What is the difference between the crosspoint and the Northwest ring?
The ring allows for more freedom of movement
Where is the northwest ring positioned?
Inferior to C7
Slightly towards the non-amputated side
What does BAHA stand for?
Bio-mechanically aligned harness anchor
What is the BAHA?
A high strength, lightweight, non-metallic harness component.
What does the BAHA want to improve?
The biomechanics of the figure 8 harness
How does the BAHA improve the biomechanics of the harness?
Optimizes the harnesses axilla angle
Provides a more efficient cable control pathway
Where should the BAHA be positioned on the body?
Inferior to C7
Slightly towards the non-amputated side
What are the four types of TR elbow joints?
Flexible
Rigid
Step up
Locking
What is the Flexible TR elbow joint made of?
Fabric
Leather
Metal
Dacron Webbing
What does the flexible TR elbow joint allow?
Maintain 50% of rotation
Free pronation and supination
What are the two types of Rigid TR elbow joints?
Single axis and Polycentric
What does the single axis Rigid TR elbow joint do?
Stabilizes the socket preventing pronation and supination
Protection of the residual limb against torque
What are the advantages of the polycentric Rigid TR elbow joint?
Increased distance from epicondyle axis to anterior socket trim
Limited tissue bunching in the bicipital fold
Increased elbow flexion ROM
Who are Rigid Friction Joints used for?
Very short TR or elbow disarticulation pediatric amputees
What does the Rigid Friction Joint function as?
Transhumeral prosthesis
What does the Rigid Friction Joints allow?
Positioning of elbow flexion/extension for small children
When are step-up joints used?
Split Socket
Very short TR <35%
Limited ROM
Patient with socket with high anterior trimlines
What are the advantages of the Step-up joint?
Allows increased flexion beyond 90 degrees.
Allows strong flexion with limited ROM
What is the Step-up joint geared at?
2:1 constant ratio
What is the sliding variable ration step-up joint?
Varies the amount of force needed throughout the ROM.
Initial flexion 1:1
Higher ratio mid-range
Less at end of range
When is the Residual limb activated locking hinge used?
Very short TR with split socket
Inadequate strength
ROM
Residual limb surface area
What cable is used with the Residual limb Activated locking hinge?
Split housing fair-lead control cable
What formula is used to determine Bilateral length?
Carlyle formula
What is the humerus length based on the Carlyle formula?
.19 x Body Height
What is the forearm length based on the Carlyle Formula?
.21 x Body Height
What two measurements make up the forearm length?
Lateral Epicondyle to styloid
Styloid to thumb tip
What is the ratios of a quadri-membral amputation for the forearm.
Forearm=.19/.21 x measured humerus length (Apt)
Who are the flexible hinge joints for?
Long Trans-radial amputation
Wrist disarticulation
Trans-carpal amputation
Where is the proximal and distal attachment of the flexible hinge joint?
proximal-triceps pad
distal-prosthetic forearm
What is the disadvantage of the single axis Rigid TR elbow joint?
Without proper alignment patient will not be able to maintain normal ROM for elbow flexion and extension
Who are Rigid hinges made for/
Amputation at or above mid forearm
Who are single axis hinges made for?
Short trans-radial patients
Who are polycentric hinges made for?
Short trans-radial
Very short trans-radial
For a Residual limb-activated locking hinge, what produces elbow flexion?
Glenohumeral flexion
What are the two types of step up hinges?
Sliding action-requires split action cable
Geared-Can use Bowden Cable
