Monday, June 17, 2024

Re: Custom silicone injection molded liner

Markus Saufferer

Colleagues,
Here are the responses to my original post, which is at the bottom of this page. There are numerous commercial sources for custom silicone liners, including OttoBock. However, the point of my post was to get some advice on making my own (inexpensive) silicone test socket / liner. Thanks for all who responded.

Touchbionics is able to provide you with what you want.

Dragon skin is the product you use it’s platinum cure silicone which is the proper medical grade silicone for Pt skin, they have a fast and slower cure time and the slower is best for removing air bubbles.

I would not use a liner on a wristdisarticulation. Go with a hard socket if possible. Problem solved.
A continued response to your question, before silicone liners became available off-the-shelf we would laminate them and would use stockinette as a reinforcement. I’m sure we bought the silicone from Fillauer. Do not remember the exact quantity of resin but at the most two stockinette should do. Good luck.

We use milled silicone and have used some injection processes for unique cases. We have worked with many challenging cases across the country. Our pricing is not bad either. If you would like more information visit our website at newwaveprosthetics.com .

Call Touch Bionics and ask them. I’m not certain how they will help, but I bet their tech could give you some ideas.

I did quite a few custom silicone liners and my favorite was a multi durameter liner with Smooth-on’s Dragon Skin 10A under a lamination of Shin Etsu’s 1310 ST. I usually added one thin nylon stocking in the lamo. Sounds complicated but once you get the technique down, it is easy. Did lots of peds and there was never a liner to fit a 2 year old.

Check out http://www.renewmaterials.com/ . They have a series of DVDs you can order that are helpful in getting started with injection molding of silicone. RTV silicones are suitable for definitive liners, however the HTV silicones that are rolled work much better. The HTV silicones definitely require additional upfront costs in tooling. You can make liners that have a combination of HTV and RTV silicones. This way you can have different material characteristics and durometers where required.

Regarding fabric reinforcement, it all depends on the patient’s presentation and needs. The best thing about doing custom silicone yourself is that the sky is the limit when it comes to possible options and configurations. Depending on the different type of fabric that you use and whether it is embedded between layers of silicone or just on the surface will give you different mechanical properties.

The silicone can be connected to the socket with embedded anchors, Velcro, an umbrella for a pin lock, or even with wedges of silicone that key into notches in the socket.

I hope that gets you going in the right direction. Good luck with your project. Once you get the silicone bug it’s hard to cure it. There is a learning curve though, and silicone is not cheap no matter who you buy it from. You will go through a lot of silicone initially as you experiment with it. If funding is a concern, you might be better off using Ottobock as they will certainly get you to a finished product faster and for about the same cost as what you will spend on tooling and silicone. In addition to Ottobock, Touch Bionics can do custom silicone liners as well as Mike Carpenter with New Wave Prosthetics, http://www.newwaveprosthetics.com/ . However, if you plan on using the skills and knowledge that you gain from working with this one patient on other cases in the future, then yes, it is definitely worth the time and investment to learn about silicone.

Markus Säufferer, B.Sc.(Kin), C.P.(c)

1145 Dufferin Cres.
Nanaimo, BC
250.591.1816

> On Nov 21, 2016, at 11:05 AM, Markus Saufferer wrote:
>
> Hello Colleagues,
> I am working with a wrist disarticulation myo-electric fitting and have used Ottobock silicone liners for this in the past. These liners are durable and high quality but can be very expensive, especially if funding is a concern. This fitting is challenging and I would like to have the ability to experiment with a few different liner configurations prior to going all the way. Does anyone have experience or recommendations as far as using high-durometer injection molded silicone (Smooth-On ?) for making such a liner? What durometer works best? Do you use reinforcing stockinette? Is this a durable option or just suitable as a test liner? How have you connected or adhered this liner to the rigid socket?
> Thanks,
>
> Markus Säufferer, B.Sc.(Kin), C.P.(c)
>
>
>
>
>
> 1145 Dufferin Cres.
> Nanaimo, BC
> 250.591.1816
>

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