Intriguing TF Socket Concept
Joe Leal CP(r) is one of the most creative prosthetists I have ever known, and he has helped me succeed with very difficult fittings on more than one occasion over the years. He was one of the first to advocate aggressive early management of traumatic upper limb amputees, and his clinical results helped establish that functional fitting within 30 days of injury substantially increased long term success with a prosthesis. About ten years ago, he sold his thriving practice to NovaCare and ultimately took an early retirement due, in part, to the non-compete restrictions in sale.
A few weeks ago, Joe contacted me to say that he has been developing an approach to fitting transfemoral sockets that seems to provide better coronal plane stability than ischial containment. He has kept tabs with many of his former patients, and now has ten-year follow-ups confirming that they continue to wear the sockets he designed rather than subsequent replacements they have received over the years. Intrigued, I arranged to meet him in Chicago to observe his technique. Over a three-day period, we fitted ten test sockets to amputees with short to very short femoral remnants. Frankly, I was stunned by what I saw.
This case was typical. As you can see in this photo, despite several inches of redundant tissue, this lady's femur is actually quite short. And, it is very difficult to capture since it is buried deep in very, very soft tissues. She also has a massive amount of anterior pelvic tilt, making IC fitting a real challenge since the pubic ramus so low.
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Joe fit her first, to demonstrate his methods; later, I tried to replicate his approach. Surprisingly, with both sockets, it appeared that there was zero gapping at the lateral proximal wall during midstance. In fact, if anything, both sockets seemed to move toward the midline of the body during single limb support! You can take a look for yourself by clicking on this short Video Clip.
I have never seen a transfemoral socket move toward the midline during single limb support: they generally move laterally, in a varus direction. Frankly, I don't fully understand what's happening with Joe's socket design. But, the patients reported that they felt the socket "hug" their flank under weightbearing and stated that they felt more stable and secure as a result. I checked the alignment carefully, and could not detect anything that would explain this phenomenon, so perhaps Joe's hypothesis that this is a socket-induced change will prove to be correct.
The socket shapes looked pretty typical, too, so I found no gross contour differences to explain this result. And, after the usual test socket refinements, the amputees reported that the sockets were very comfortable and that they could not detect any concentrated pressure areas that might explain the added stability they perceived.
We will be fitting another series of patients shortly, with different residual limb lengths and shapes, to see if the results are the same as with these preliminary cases. If so, then the next step will be to try to determine what factors are causing the apparent increase in midstance stability in the coronal plane. I'll report on the next group of trials in a subsequent Corner.
