Chapter 6B- Harnessing and Controls for Body-Powered Devices Flashcards
What type of harnessing system is used for transradial amputees?
One-cable/ Single-control system
What is another name for terminal devices?
Prehension devices
What type of motion applies tension to the control cable?
Shoulder motion
How much prehensile force is produced by each rubber band?
0.45 kg or 1lb
what encases the control cable for most of its length?
Flexible stainless steel housing
The upper end of the control cable attaches to what through what?
Attaches to the Triceps pad through the housing and crossbar assembly.
Where does the distal end of the cable attach and through what?
Midforearm level of the prosthesis by the base plate and retainer
What does the housing for the cable do?
Maintains a constant length of the control cable regardless of the angular attitude of the anatomic elbow joint
How can you tell the housing is doing its job?
The amount of body motion to operate the terminal devices remains the same when the elbow is flexed at 135 degrees and fully extended.
What is the standard harness for a unilateral adult transradial amputee composed of?
2.5 cm (1 in) wide Dacron webbing
How is the webbing arranged for a standard harness for a unilateral adult transradial amputee?
Arranged to form a horizontally oriented figure of 8
What is the purpose of the axilla loop?
To serve as an anchor for the two other straps
Where is the axilla loop located?
Encircling the shoulder girdle on the non-amputated side
What is another name for the anterior support strap?
Inverted Y suspensor
Where is the anterior support strap located?
Originates at the axilla loop
Passes over the shoulder on the amputated side
Attaches to the anteroproximal margins of the triceps pad of the prosthesis.
What is the primary purpose of the anterior support strap?
To resist displacement of the socket on the residual limb when the prosthesis is subjected to heavy loading
Where does the control attachment strap originate and attach?
Originates at the axilla loop
Terminates at the proximal end of the prosthetic control cable
What is the purpose of the control attachment strap?
to act as an extension of the control cable.
Where is the control attachment strap located?
Between the spine and inferior angle of the scapula
What anatomical movements creates the operation of the terminal device?
Scapular abduction
Shoulder flexion
What is the name of the area where the axilla loop crosses itself?
The cross point
What are the two attachment option for the cross point?
Sewn together
Stainless steel loop
What is the name of the harness if a stainless steel ring is used at the cross point?
Transradial, Ring-type harness
What is the advantage of a ring-type harness?
Less restrictive
Where should the cross point be located?
Below the spinous process of C7 and slightly towards the non amputated side
What is the primary body control motion for operating the terminal device of a transradial prosthesis?
Glenohumeral flexion
What primary body control motion is used to operate the terminal device when needing to button a shirt or other movements close to midline with a transradial harness?
Biscapular abduction
What is a disadvantage of the standard figure of 8 harness for transradial amputees related to the axilla loop?
Comfort- Need extra padding and worn over an undergarment
Tension creates excess axilla pressure- lead to skin irritation and possible neurotrophic changes
When should a nonstandard transradial harness system be used?
When the patient is engaged in strenous work activities with continuous lifting of heavy objects
What is another name for a nonstandard transradial harness?
Heavy-duty harness
Shoulder-saddle harness
What is the difference between the heavy-duty harness and the standard harness?
When tension is applied it is distributed over the shoulder on the amputated side rather than the axilla
Where is the leather shoulder saddle located?
Amputated side
Where are two support straps on a shoulder saddle extended from, when using a heavy-duty harness?
The posterior portion of the shoulder saddle through D-rings
Where are the D-rings located for the support straps of the shoulder saddle, when using a heavy-duty harness?
On the medial and lateral surfaces of the triceps pad
Where do the two shoulder saddle support straps attach, when using a heavy-duty harness?
Anterior surface of the shoulder saddle.
How is the shoulder saddle anchored?
A Chest strap
What body controlled motions does the patient use to operate the heavy duty harness?
Glenohumeral flexion
Scapular abduction
On bilateral transradial amputees, what is the difference between the harnessing?
The control attachment strap becomes the anterior support strap
When using a step-up elbow hinge, what are the disadvantages?
Requires double the force
Excess pressure/discomfort on the volar or radial surface of the remaining transradial amputation.
What modifications to the harnessing can be done to a step-up elbow hinge, to provide more comfort for the patient?
Split cable housing into proximal and distal segments (similar to transhumeral)
Where is the proximal piece of the housing attached for a split cable designed harness of a short transradial amputee?
The triceps pad
Where is the distal piece of the housing attached for a split cable designed harness of a short transradial amputee?
The prosthetic forearm
For the modified harness of the step-up elbow hinge, where is the control cable exposed?
Anterior to the elbow joint
What movement occurs when tension is applied to the control cable by the glenohumeral flexion?
Elbow flexion
For sockets with anatomical suspension, what anatomical landmarks hold the transradial socket on?
Olecranon
Humeral Epicondyle
Antecubital fossa
What does anatomical suspension eliminate in regards to the harnessing?
Triceps pad
Anterior Support Strap
What does an anatomically suspended socket have for a harness?
Axilla Loop
Control attachment strap
What is the disadvantage of using a anatomically suspended prosthesis?
Long-sleeved clothing is difficult to wear
