BOSTON — Jason Kahle, CPO, FAAOP and M. Jason Highsmith, DPT, CP, FAAOP from the University of South Florida School of Physical Therapy and Rehab Science delivered their Thranhardt award winning prosthetic lecture on their clinical trial evaluating the effects of removing the ischial ramus containment (IRC) brim in a transfemoral interface at the American Orthotic and Prosthetic Association National Assembly here.
“We’re still debating what vacuum does for us in prosthetics. So that gave us the opportunity to look at brim or brimless,” Kahle said. “The history of vacuum assisted suspension has been fitting transtibials only because the proximal seal requires a suspension sleeve. But if we can integrate a VAS system with a transfemoral and do it well and efficiently, would we be able to lose the ischial containment? If we have better thigh control, it should equal better pelvic control which should equal better spinal control. So the whole theory is if the vacuum is doing its job, we might be able to get rid of that brim.”
Kahle and his colleagues fitted 12 transfemoral amputees with both a Symmetry IRC and a brimless socket and gave them 2 days to assimmilate to the sockets. The subjects then underwent a series of tests and X-rays evaluating skeletal kinematics, internal interface pressure, agility and balance and gait analysis. The subjects also filled out an evaluation questionnaire are the subjective qualities of the sockets such as body sensations, socio-emotional effects, mobility and satisfaction.
They found that the brimless and IRC performed equivalently on the majority of the tests, and the femur was held in the same position in both socket designs. In the questionnaire results, most of the subjects favored the brimless design.
“So our conclusion [between the IRC and brimless designs] was that we found equivalence,” Kahle said. “So what does that mean as far as clinical significance?”
Kahle answered this question with a video of a transfemoral amputee who had lost his leg in an explosion while serving in Iraq 7 years prior. The man had not been able to run since his amputation due to the design of his IRC socket, but upon wearing the brimless socket for the first time, he was able to run relatively well, matching the speed and stride of another amputee wearing an IRC design who was running alongside of him.
For more information:
Kahle, J. Transfemoral interfaces with vacuum assisted suspension comparison of gait, balance, biomechanics and subjective measures. Presented at the American Orthotic & Prosthetic Association National Assembly 2012. Sept. 6-9, Boston.