Why does this look funny?

So today is my second day back from a great Independence Day holiday with friends and family. On Tuesdays, I get to spend a lot of time with my resident,who is progressing quite nicely and is maturing into a very good clinician. But today she asked a good question, why does the socket look so funny? When you hold it up to the light, you can see that the top half of the socket allows light to come through while the bottom half of the socket does not. This socket is for a geriatric patient who is a low activity patient and one of the big concerns outside of the obvious like a comfortable fit is how heavy the prosthesis is. The materials used on this prosthesis are to keep the weight of the socket as light as possible. The dark area that you see ate areas of carbon which are used primarily at the distal end (bottom) to attach the socket to the block that connects it to the components. That attachment is the mechanical weak spot in any prothesis where everything is bolted to a laminated socket. The foot that we used on this prosthesis is not only lightweight, but it also allows quite a bit of flexibility to absorb ground reaction forces to reduce the pressures at the attachment point. This allows us to make a socket, which is much thinner with less material, which corresponds to less weight! But the way the technician laid this up, provides reinforcement at the weak point, which is at the bottom of the socket. So if you see a socket that permits light to “come through”, don’t necessarily think it’s not made to hold your body weight safely, know that they reinforced the bottom to make sure it can handle the ground reaction forces applied during weight-bearing and walking safely.