Researcher Investigates Effect of Socks on Residual Limb Volume

ORLANDO, Fla. — Through her research with transtibial amputees,
Joan E. Sanders, PhD, determined that
limb fluid volume is specific to each patient and that
practitioners should not assume that adding a sock would decrease this volume.

Sanders closely monitored 26 unilateral and three bilateral transtibial
amputees – all of K2 or higher activity levels – while wearing their
own self-selected prosthesis for the study. Limb volume was measured with a
bioimpedance analyzer continuously throughout a series of walking tests with
and without a 1-ply sock.

“The way it works is we apply a current across a pair of outer
electrodes … and then we measure voltage between the inner pair of
electrodes,” Sanders said, at the
2011 Annual Meeting and Scientific Symposium of the American
Academy of Orthotists and Prosthetists
. “You see a lot of change while
they are walking. That’s because they are pulling in and out of the
socket. Our results show that 22 of 29 [participants] decreased in volume when
the socket was added and 18 of 29 increased when the socket was removed. There
was a lot of variability among the participants.”

Variations taken into consideration included: vascular disease; high
blood pressure; being overweight and obese and smoking habits.

“We suggest that you document which socks you’re using and be
consistent. Be careful during the fitting session,” Sanders said.
“Monitor your patients’ weight and body mass index and ask them about
their eating habits. Ask your patients about their smoking habits. These all
may give you insight as to what their limb fluid volume changes are going to be
over time.”

Sanders gave some additional insight to practitioners for proper
fabrication of devices while taking limb volume into account.

“In application of volume management, our big message is be careful
as you are developing these devices,” Sanders warned. “Adding
material to the interface or changing the size of the socket might further
reduce limb fluid volume and possibly confound your fitting within that fitting
session.” — by Jennifer Hoydicz

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