hands free hydro cast – optimising trans-femoral socket design and maximising rehabilitation...
TRANSCRIPT
Hands Free Hydro Cast – Optimising Trans-femoral Socket Design and Maximising Rehabilitation Potential
Buis AWP, McGarry A, Kamyab M, Murray KD, Hillman S
Biomedical Engineering, University of Strathclyde, Glasgow, UK
Introduction
• Statement of problem (Why)
• Implementation of a “good” fit
• Methodology (What & How)
• Results
• conclusion
Statement of problem
• The purpose of a socket is to provide a mechanical connection
between the skeleton and the rigid structure of the prosthesis.
• The dominating concepts are the Quad and Ischial cont.
• How stabilising are those sockets?
• Are they reproducible?
• Can we do better?
Implementation of a “good” fit
• Socket fit criteria:
o As “stiff” as possible coupling
o No tissue damage
o Minimum discomfort
Implementation tools;
o Surface matching
o Volume matching
• Is it possible to distribute the load to the different transmission elements in a controlled
way?
• Yes, if the force flow distributes itself proportionally to the stiffness of the available path!
Implementation of a “good” fit
Rubber Block Metal Block Rubber Block
“Let nature deform the soft tissues in such a way that the
stiffest path principle is achieved”
• Copy of the existing Ischial containment socket.
• Pressure cast socket according the Hydro cast principle.
Methodology
Methodology (work packages)
1. Dynamic interface pressure (ideally shear)
2. Femoral stability
3. User performance outcome measures
• Kinetic (forces)
• Kinematic (position in space and time)
Methodology
• Dynamic interface pressure
• Validated Tekscan™ pressure measurement system
Methodology
• Femoral stability
Methodology
• User performance outcome measures
• Kinetic (forces)
• Kinematic (position in space and time)
• Dynamic interface pressure
Hydro
Ischialcontainment
A M P L
Results
Video
Ultra sound
X section socketMedial
Anterior
Sensor
Results
Results
A
Medial
Hydro Cast
Lateral
P
Ischial Containment
A
Medial
Lateral
P
• User performance outcome measures
Summary
• Speed slightly higher with the old socket, but it was noted that the
subject’s speed increased as she became more accustomed to the new
socket.
• Stride length slightly longer with the old socket, effected via increased
step length bilaterally.
• Cadence and double support time much the same for both conditions.
• Single support time on the right a little decreased with the new socket.
• Clear differences between pistoning and gapping were observed.
Indicating that the Hydro concept is more stable.
Results
Conclusion
• No significant pressure distribution differences.
• Shear should be investigated!
• No significant Kinetic and kinematic differences.
• Significant stability differences in direction,
pistoning and gapping in favour of the Hydro concept
prosthesis.
Thank you!