This is yet another subject of controversy. Clearly another major knee
seminar is needed to discuss
“Which Knee to Use When,
and What Knees Would We Like to see Developed.”
It seems to be good bet to use a knee with a SNS hydraulic unit when and if
you can. However, we don’t get the benefit of 4 bar geometry for toe
clearance and higher center of virtual rotation-
There is one endoskeletal knee frame built by USMC and sold by Mauch
(Flex-Mauch) which has a SNS unit in it. This frame has considerable
limitations I am told.
In the last 3 years, I have asked manufacturers why they haven’t come out
with an improved 4 bar knee with a SNS unit. The consistent answer has been
“difficult engineering problems”
It has now come to my attention that Sujatha Srinivasan , while a graduate
student at the University of Toledo (OHIO), has developed a 4 bar knee with a
SNS unit. This was done under the guidance of
Dr. Steven Kramer a UT professor of Mechanical Industrial Engineering
and in conjunction with Vern Swanson, a creative prosthetist and President
of Swanson Regional Orthotic and Prosthetic Research Center
(an amputee himself).
It is my understanding that more research dollars may be needed to truly
bring this knee unit to market. It is also a possibility that this important
contribution may be languishing for lack of continued focus by the patent
holders. Sujatha is not currently involved in its continuing development
because of possible conflict of interest with her current employer.
I would like to recommend that we, as prosthetists, give our support and
encouragement to Sujatha Srinivasan, Vern Swanson, and Steven Kramer,
to continue with the development of this promising knee.
What I would ALSO like to see, is a weight-activated-stance-control
four-bar knee for patients who, for reasons of funding, activity level, or
need for reducing componentry weight, would prohibit the use of a SNS unit.
Engineering students-Prosthetist Engineers, this is another opportunity.
BTW, My awareness of this new knee comes from an article in the UT Alumni
Magazine. It was given to me by a local colleague who received it from one of
his clients. It seems like something we should have seen in one of our
Mark Benveniste CP
VA Med. Ctr. Houston TX