WK8: Force and Excursion Flashcards
What type of lever is TH BP Px
3rd class lever
* Fulcrum: elbow center
* Force: Elbow flexion attachment
* Resistance: weight of forearm + TD
Force
UL BP Control
- Power the body must generate to actuate BP components or switches
- Challenging with pediatric pts, short RL, and neuromuscular impairments
Excursion
- ROM generated OR distance the intact segment must travel to actuate componentsor switches
- increasingly limited with proximal levels of amputation or joint pathology
Excursion Required
- E-400: cable must move 2.5” w/in cable housing to flex elbow
- TD: 2” to fully open TD
- 4.5” of total excursion needed in full elbow flexion
Depends on distance between EFA and EC
If Elbow Flexion Attachment is moved further away from Elbow Center, ** excursion is required
MORE
If Elbow Flexion Attachment is moved closer to Elbow Center, ** excursion is required
LESS
Elbow Flexion Attachment
Also: Forearm Lift Tab
Purpose: keeps cable and housing away from mechanical elbow center
What is initial placement of EFA
adjustable EFA Jig
- 25 mm anterior to EC
- 30 mm distal to EC
Closer to elbow axis = more proximal
Adjustable EFA Jig
- less excursion required
- more force required
Further from elbow axis = more distal
Adjustable EFA Jig
- more excursion required
- less force required
Proximal Base Plate & Retainer
Keeps cable and housing above cut end of humerus
Initial Placement
Proximal Base Plate & Retainer
- 25 mm proximal to cut end of humerus in posteriolateral quadrant
- more distal = more excursion captured
- more proximal = less excursion captured
Cable and Housing Length
- CH - fully flex elbow, TD supinated, and fully open: 3 mm clearance
- C - elbow fully extended, TD pronated, and fully closed: 3 mm clearance between hanger and proximal housing
