The one thing that I know with certainty is that to get the best result, the details that go into every prosthetic device must be perfect.
The most important part of any building is its foundation. If the foundation is shoddy, the structure's integrity will be compromised. A patient's residual limb takes many different shapes and sizes; no two are alike. Invaginations, scarring, burns, and heterotopic ossification, to name a few, all present a difficult foundation upon which to build a socket. We level the playing field by customizing about 90 percent of our silicone liners. This allows us to achieve the full contour of the limb, reduce shear forces, provide cushioning, and achieve a more even surface to serve as the foundation for each socket. We choose to use silicone instead of TPE because it is more hygienic, does not pack out over time, and provides improved protection against impact forces. We almost always default to vacuum as our suspension method because of the intimate connection it offers the limb.
All of the facilities that I have visited do clear, static check sockets to evaluate the fit. Only a few are doing dynamic check sockets. While a static fit provides valuable information, there is only so much you can tell from standing up into a socket. It does not replicate in any way the forces that will be put on a limb while ambulating, particularly after an extended period of time. I believe that a dynamic check socket is crucial to an optimal outcome, not only for fitting but also for alignment purposes. We mount our sockets onto an oversized mounting plate with Bondo®, then reinforce it with fiberglass wrap. The large mounting plate gives us adjustability in our components' M-L and A-P placement, as well as the ability to initially set the flexion, adduction, etc. during the mount.
It is almost impossible to see everything that happens during gait with the human eye. Is the pylon really vertical at mid-stance? I would venture to say that it probably is not. There are many alignment devices and tools available on the market, such as the Otto Bock HealthCare, Duderstadt, Germany, L.A.S.A.R. Posture, (which only does static alignment), and Orthocare Innovations', Oklahoma City, Oklahoma, Compas™ computerized prosthesis alignment system. These products are expensive and can be time-consuming to implement. A much simpler solution is to use a digital camera with a video function. Record your patient from the coronal and sagittal views, upload the video to your computer, and analyze the film using basic video software. We are able to slow down the video frame by frame and optimize the alignment accordingly on our alignment plate. Sometimes the changes are drastic, such as making a slide change. Other times an adjustment is as simple as putting in an extra turn of flexion to make sure the pylon is truly vertical at mid-stance, instead of having the sound side trail or lead by one or two frames.
Check sockets are easy and less costly to adjust than laminated sockets. When a patient's residual limb is put into suction/vacuum suspension, it tends to shrink quickly. Keeping a patient in a check socket for one to two weeks allows us to accommodate for any volume changes as needed. It is unfortunate when you have to reduce a brand new laminated socket a week later because the patient's residual limb shrank drastically.
These procedures ensure that we deliver the highest-quality product to our patient. It usually takes more than the two check sockets we can bill for, and extra time picking things apart, but it is always worth it in the end. My residency has taught me that the pieces of the puzzle all work together; if you take any one of them away, the outcome, while still potentially favorable, is not the same.
As published in the July 2011 issue of the O&P Edge
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