Re: Total Surface Bearing Modifications- Ray Francis
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Collection
Title:
Re: Total Surface Bearing Modifications- Ray Francis
Text:
In a message dated 3/1/01 10:47:16 PM, <Email Address Redacted> writes:
<< ..........The Alpha is notorious for its longitudinal stretch
characteristics and has no distal strength matrix to prevent it. The soft
mineral oil impregnated gel material has low adhesion characteristics (lower
than silicone anyway) and flakes apart in the distal end by the low pressures
needed in a suction suspension system. The failure of the sleeve will of
course be in the distal end as the proximal end is not sealed, but the
excessive pistoning by not pre-tensioning the pin in the original casting
process over the residuum is a major cause of blowouts in the Alpha. A fleshy
residuum needs to be pre-shaped in a tensioned configuration during the
casting process and the socket needs to be as tight at the top as it is at
the bottom....... >> Stan LaCount
Aside from my thoughts about appropriate casting techniques for a total
surface bearing socket, I think pin suspension systems without an airtight
shuttle lock seal and additional sleeve, can lead in to pistoning in many
patients and subsequent breakdown in the liner. Suspension remains focused at
the distal end.
Pre-tensioning may prevent some pistoning but may make it difficult to don.
I use a shuttle lock that is air tight in conjunction with a suspension
sleeve for the most secure suspension. What I have discovered from
experience, contrary to my theoretical perspective, is that some wearers
don't always want such a solid suspension. They may save it for athletics,
with increased sock use, or other situations. What I like about the sytem of
both pin and external suspension sleeve is the security of suspension that
may be lost with an external sleeve suspension alone when a hole develops in
the sleeve. ...... Mark Benveniste CP
<< ..........The Alpha is notorious for its longitudinal stretch
characteristics and has no distal strength matrix to prevent it. The soft
mineral oil impregnated gel material has low adhesion characteristics (lower
than silicone anyway) and flakes apart in the distal end by the low pressures
needed in a suction suspension system. The failure of the sleeve will of
course be in the distal end as the proximal end is not sealed, but the
excessive pistoning by not pre-tensioning the pin in the original casting
process over the residuum is a major cause of blowouts in the Alpha. A fleshy
residuum needs to be pre-shaped in a tensioned configuration during the
casting process and the socket needs to be as tight at the top as it is at
the bottom....... >> Stan LaCount
Aside from my thoughts about appropriate casting techniques for a total
surface bearing socket, I think pin suspension systems without an airtight
shuttle lock seal and additional sleeve, can lead in to pistoning in many
patients and subsequent breakdown in the liner. Suspension remains focused at
the distal end.
Pre-tensioning may prevent some pistoning but may make it difficult to don.
I use a shuttle lock that is air tight in conjunction with a suspension
sleeve for the most secure suspension. What I have discovered from
experience, contrary to my theoretical perspective, is that some wearers
don't always want such a solid suspension. They may save it for athletics,
with increased sock use, or other situations. What I like about the sytem of
both pin and external suspension sleeve is the security of suspension that
may be lost with an external sleeve suspension alone when a hole develops in
the sleeve. ...... Mark Benveniste CP
Citation
“Re: Total Surface Bearing Modifications- Ray Francis,” Digital Resource Foundation for Orthotics and Prosthetics, accessed November 25, 2024, https://library.drfop.org/items/show/216232.
