MT: Prosthetic Knee Control Mechanical Flashcards
1
Q
Mechanical Knee Control
A
- gravity
- friction
- springs/elastic
- stop
2
Q
What can swing control be provided by
A
- mechanical or fluid friction resist
- mechanical or fluid assist
3
Q
Mechanical Friction Swing Resistance
A
- simple, inexpensive, rugged
- resistance is adjustable
- constant friction = 1 speed
4
Q
Swing Control Option - Assist
A
- increases knee ectension force during swing
- late swing: aids full knee extension at heel strike
- early swing: resists knee flexion
- flexion assist is not needed since force generated during gait is sufficient to achieve necessary flexion
5
Q
Single Axis Constant Friction Indications
A
- single speed walkers with excellent hip control
- preschool children
- maximum durability is required
6
Q
Single Axis, Constant Friction Limitations
A
- fixed cadence only
- no inherent stability
7
Q
Stance Phase Control
A
- resists knee flexion & knee extension during stance
- provides stability during loading of prosthesis
- external knee flexion moment
8
Q
Knee stability
A
- manual locking
- friction brake
- polycentric linkage
- outside hinges
9
Q
Mmanual Locking Advantage
A
- provides maximum inherent stability
- lock can be integrated into other designs
10
Q
Manual Locking Limitations
A
- disrupts gait: px too long to swing
- induces gait deviations: circumduction, hip hiking, vaulting
- makes sitting/falling more precarious
11
Q
Friction Brake Benefits
Weight activated stance resitance
A
increases inherent knee stability during weight-bearing; allows flexion/extension during swing phase
12
Q
iFriction Brake Limitations
weight activated stance resistance
A
- can’t flex knee under load
- must unload fully to sit
- cant descent stairs foot over foot
- bilateral cant jakcknife if falls
13
Q
Polycentric Linkage
A
- four bar design common
- multiple axes of rotation add biomechanical features that enhance function
- knee stability in early stance
- increased toe clearance in midswing
- greater range of knee flexion
14
Q
Instantaneous Center of Rotation
Polycentric knee
A
- point where anterior and posterior bars intersect
- defines the effect point of rotatoin of the knee
- typically, proximaal and posterior to knee mechanical
15
Q
Centrode
A
- characteristic pathway of ICOR as knee flexes and extends
- combines stability in early stance with ease of flecion in terminal stance
