Subject: Summary: Archiving shape and alignment with CAD

Subject: Summary: Archiving shape and alignment with CAD

Zzharv

9/23/2010

Colleagues,

Here's a summary of information I've gathered, my post from last week, and
responses:

Practices that do CAD/CAM exclusively, may invest more time up-front but
have an
easy way of archiving shape and alignment for future socket design changes
or
duplication. This is done primarily by positioning the carver mandrel in
the
proper bench alignment. If perhaps, the first socket is off 3 ply and 1/2,
for
example, the model can be reduced and the mandrel can be re-positioned on a
proper axis.
Practices that use hand casting and plaster models may benefit from CAD/CAM
once
a good fit and alignment are established. My question asked if anyone is
having
any luck in imaging shape AND alignment. In the case of a bulbous shape, it
is
difficult to pour up and remove the socket without cutting it with a cast
saw.
A couple of people who responded suggested using alginate and a vertical
jig
for this purpose, and I've done this a number of times with success, but the

process is time consuming when we get busy and gets you thinking, there's
got
to be a better way!...
It turns out, there are ways to use CAD CAM and reference alignment marks.
One
such way would be to wrap plaster around a positive model, draw up reference

lines, cut along those lines, scan the inside of the casts, merge them, and
email the file. Biosculptor's imager will capture shape and alignment, but
guesses at the distal 1/2 of the socket. That works well embracing their
recommended clinical technique which is using a 2 part silicone injected
distal
end pad.
It seems that a hybrid approach to CAD CAM may be an alternative worth
investigating, since many prosthetists (including myself) have tried imaging

devices and went back to hand casting. This way, a prosthetist could use
any
method they choose to arrive achieve socket fit and then push a button and
Wallah!, a new socket appears... at least it will appear sooner and less
effortlessly than current methodology. In this respect, automation could
cut
out some of the steps necessary in order to reproduce a definitive socket.
By
streamlining our processes, more time can potentially be spent with patients

instead of working in the lab.

Zach

Original question:


I'm wondering if anyone has figured out a way to precisely capture socket
shape
AND alignment in order to streamline the process in this common scenario:
>>
>> Patient walks in test socket for several days or weeks and both heat
>> modifications and alignment changes are made. Patient and prosthetist
decide
>> that time is right to finalize project and change to carbon fiber. The
socket is
>> poured up in a vertical jig and in the worst case scenerio, if the shape
is
>> bulbous, such with many symes or KD's, the test socket has to be cut off.
This
>> forces the patient to perhaps go back to wearing an older ill-fitting
socket and
>> wait a at least a few days for the definitive socket to be complete.
>>
>> Anyone have success in digitizing a socket to capture both shape and
alignment.
>> If so, is there a central fab facility that you find works well?
>>
>> Thanks in advance, Zach
>
>
Responses:
Dear Zach, If you are primarily interest in negitive draft, you might
consider
OTTO-BOCK duplicating foam. If you are primarily intested in fidelity, you
may
want to investigate dilatency vacuum forming. In any event, you have
brought a
very intersting and relevant technical and clinical issue. Michael Wilson
CPO/LP

Hello Zach
I have a simple method. Just not simple enough to express in type. E-mail me
for
personal contact info.
Rodney

Zach,
I have extensive experience in this. Call me when you have time and I can
describe it for you.
David


________________________________

We alginate our sockets in the jig locking alignment then remove, cast and
place
back in jig lock down alignment with pins remove alginate and refill in jig.
you
are able to use same pipe and collar and since lower alignment is locked you
are
able to remove the existing setup without losing anything. we have good
success
with this procedure hope it helps.

Daniel LaRue
Inland Fabrication

Hi Zach,

If you are still at WR you have the BioScanner that can be used with
advanced
clinical technique to accomplish your goal.

Give me a call to discuss the how to or better yet if you are going to
attend
AOPA we can discuss it there.

Best,

Alan


Alan R. Finnieston, CPO, LPO
President

Zach,
I've poured the socket in a vertical jig using alginate, then wrapped and
re-poured. It's a bit time consuming and messy but it keeps my patient in
the
check socket while I do definitive fab and seems to work well.
Chris