Surgical sutures are mindless threads no more. Researchers have now coated them with sensors that could monitor wounds and speed up healing.
The electronic sutures, which contain ultrathin silicon sensors
integrated on polymer or silk strips, can be threaded through needles,
and in animal tests researchers were able to lace them through skin,
pull them tight, and knot them without degrading the devices.
The sutures can precisely measure temperature—elevated temperatures
indicate infection—and deliver heat to a wound site, which is known to
aid healing. And John Rogers,
professor of materials science and engineering at the University of
Illinois at Urbana-Champaign and inventor of the smart sutures, imagines
that they could also be laden with devices that provide electrical
stimulation to heal wounds. "Ultimately, the most value would be when
you can release drugs from them in a programmed way," he says. The
researchers could do that by coating the electronic threads with
drug-infused polymers, which would release the chemicals when triggered
by heat or an electrical pulse.
The smart sutures, reported online in the journal Small,
rely on silicon-based devices that flex and stretch. Rogers and his
colleagues make the devices with silicon membranes and gold electrodes
and wires that are just a few hundred nanometers thick and patterned in a
serpentine shape. The technology, which they have also used in inflatable catheters and medical tattoos (see "Stick-On Electronic Tattoos"), is being commercialized by MC10, a Cambridge, Massachusetts–based startup Rogers cofounded (see "Making Stretchable Electronics").
The researchers first use chemicals to slice off an ultrathin film of
silicon from a silicon wafer. With a rubber stamp, they lift off and
transfer the nanomembranes to polymer or silk strips. Then they deposit
metal electrodes and wires on top and encapsulate the entire device in
an epoxy coating.
They have built two types of temperature sensors on the sutures. One
is a silicon diode that shifts its current output with temperature; the
other, a platinum nanomembrane resistor, changes its resistance with
temperature. The micro-heaters, meanwhile, are simply gold filaments
that heat up when current passes through them.
All the materials used in the devices are safe for use in the body,
and the biggest challenge was to make the sutures flexible, Rogers says.
Silicon is brittle, so making the nanomembranes as thin as possible and
laying them out in a winding pattern was key for elasticity. Placing
the silicon halfway between the top epoxy and bottom polymer surfaces of
the suture is also crucial. "When you bend the entire construct, the
top surface is in tension and the bottom is in compression, but at
midpoint the strains are very small," he says.
The researchers have tested the sutures' mechanical flexibility and
toughness on incisions in rat skin, but they haven't tested the
temperature sensing and heating capabilities in animals yet. They are
also working on making the devices wireless.
divendres, 21 de setembre de 2012
dilluns, 17 de setembre de 2012
Injury. 2012 Aug 23.
Extra- and intramedullary implants for the treatment of pertrochanteric fractures - Results from a Finnish National Database Study of 14,915 patients.
Yli-Kyyny TT, Sund R, Juntunen M, Salo JJ, Kröger HP.
Department of Orthopedics, Traumatology, and Hand Surgery, Kuopio University Hospital, P.O. Box 1777, 70211 Kuopio, Finland.
We analysed registry-based data on 14,915 patients treated for pertrochanteric fracture obtained from the Finnish Health Care Register during the years 1999-2009. Data on the comorbidities, residential status and deaths of the cohort were extracted from several Finnish registries using patients' unique personal identification numbers. The use of intramedullary implants increased substantially during the study period. One-year mortality was slightly higher in the patients treated with intramedullary implant (26.6% vs. 24.9%; P=0.011). In the first year after the fracture, there were more new operations on hip and thigh in patients treated with an intramedullary implant. Our findings suggest that more expensive intramedullary implants do not lead to better clinical outcomes than extramedullary implants for the treatment of pertrochanteric fractures.
Publicat per Tutordecot a 7:56:00