WK4: Socket Design & Suspension Flashcards
Main Goals
Socket Design for TR/WD
- Serve as an interface (RL to Px)
- Stable translation of forces (BP)
- Work with or provide suspension
- Allow/accommodate existing ROM
Other considerations
Socket Design for TR/WD
- limb length
- desired control
- desired suspension
Describing Sockets
Socket Design for TR/WD
Donning
* Pull in
* Push in
Interfaces
* Skin
* Fitting socks
* Gel liner
Suspension Options
- External
- Self Suspending
- Mechanical
- Atmospheric
External
Suspension Methods
Harnesses
Self-Suspending
Suspension Methods
Anatomical
proximal or distal
Mechanical
Suspension Methods
- Pin, Lanyard, or Magnet
- requires gel liner
Atmospheric
Suspension Methods
- Suction (liner or skin fit)
- Active Vacuum (liner only)
Common Plaster Modifications
Socket Design for TR/WD w/ Harness Suspension
- Reduce plaster in fleshy areas
- Relieve over prominent bony landmarkes
- Accentuate “screwdriver” shape
Bony Landmarks in TR/WD
Socket Design for TR/WD w/ Harness Suspension
- Distal cut end of radius (TR)
- Distal cut end of ulna (TR)
- Distal end of radius and ulna (WD)
- Lateral epicondyle
- Medial epicondyle
- Olecranon process
Trimlines
Socket Design for TR/WD w/ Harness Suspension
Trim lines will be higher for shorter limb lengths
- For WD or long TR, do not encompass
epicondyles
- For very short TR, as high as possible to still
allow donning and desired elbow ROM
Proximal Anatomical Self-
Suspending TR Socket Designs
- developed in 1960s for very short TR limb differences
- severely restrict voluntary pronation and
supination - Well suited for passive prostheses (but can be used with BP and EP)
Muenster
Proximal Anatomical Self-
Suspending
Designed to provide a simplified prosthesis
for use with very short transradial limb
difference
* Emphasizes A-P soft tissue
compression
* Allows a larger M-L dimension to
contain displaced tissues
* suitable for congenital
applications with under-developed
bony contours
Muenster Casting - Hand Position
Proximal Anatomical Self-Suspending
- Static cast with anterior brim 12 mm [1/2”]
proximal to cubital fold - biceps tendon insertion emphasized by finger tips
- Palm of hand cradles ulnar region gently
- Triceps tendon region emphasized to improve axial loading in extension
Muenster Casting - Elbow ROM in Cast
Proximal Anatomical Self-Suspending
- Limited ROM is expected: total of 70 deg flexion
range, 35-105 degrees - Pre-flexion is commonly utilized to provide ROM for at least table-top activities
NU Supracondylar Design
Proximal Anatomical Self-Suspending
- First reported by John Billock, CPO in 1972
- Allows much greater ROM at elbow with “push in” donning
- Suitable for much longer RL lengths than Muenster
- Intended for use with emerging
- EP controls but suitable for many prosthetic/orthotic applications
NU Supracondylar - Casting
Proximal Anatomical Self-Suspending
- Accurate measurements are CRITICAL!
- Static cast, with elbow flexed 45 degrees
- Intended for use with semi-flexible socket brim
European [“Otto Bock”] Design
Proximal Anatomical Self-Suspending
- Combo of Muenster and NU
- less aggressive ML and AP control
- muscle belly suspension (brachioradialis?)
- Dynamic” impression method to capture full ROM at elbow
- Suspension is most effective if pull-in donning is used to draw soft tissues into antecubital “displacement pocket”
Sauter Modication
- Removal of proximal/ulnar quadrant
over olecranon - lowers friction, cooler, less bulky
Brief Overview/Comparison
Proximal Anatomical Self-Suspending
- Muenster - AP suspension; Very Short TR; congenital
- OB - AP, ML, soft tissue suspension; Short to mid-length RLs
- NU SC - ML suspension; Mid-length & longer RLs
ALL eliminate pronation/supination
Wrist Disarticulations
Distal Anatomical Self-Suspending Socket Designs
- Usually permit voluntary pronation/supination
- Suprastyloid variants often successful for wrist disarticulation level
Practitioner Reported % (of all UL Px)
TR/WD Control and Suspension
- Harness - 42%
- Suction - 10%
- Lock/Lanyard - 14%
- Seal-in - 4%
- Vacuum - 0%
- Self-Suspending - 24%
