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The Body Electric
nents. Of course, we have more pieces of the puzzle today, but we still
don't have a complete picture of how any of the competing techniques
work.
Besides our low-current silver electrodes, there are two other basic
types of bone growth stimulators. Friedenberg and Brighton at first
placed their stiff stainless-steel wires through holes drilled into the bone
near the break. Now a "semi-invasive" refinement is used in many pa-
tients—sticking the electrodes through the flesh into the fracture gap
under local anesthetic; several may be needed for a large bone. They're
connected to a self-contained battery pack set right into the cast.
Friedenberg and Brighton patented their invention, and it's now ap-
proved by the FDA and marketed. About three fourths of the groups
treating patients use some variation on this theme.
Australian researchers under D. C. Patterson devised a spiral titanium
electrode that's placed into a notch cut in the bone on both sides of the
fracture. It's now also FDA approved and marketed. Since this device,
battery pack and all, must be implanted and removed in two separate
operations, and since the electrode usually must be left behind in the
bone, late complications may occur.
Others have taken a completely different approach, using pulsed elec-
tromagnetic fields (PEMF) to induce currents in the fracture area from
outside the body. The best-known proponents of this method, Andrew
Bassett and electrochemist Arthur Pilla, worked together at the Ortho-
pedic Research Laboratories of Columbia-Presbyterian Medical Center in
New York until 1982; Pilla is now at the Mount Sinai Medical Center.
They developed a pair of electromagnetic coils sheathed in plastic pads,
connected to a book-sized generator that plugs into a wall socket.
Having experimented with a wide variety of pulsed fields, Bassett and
Pilla found four that stimulate fracture healing. The one that works
best, which is now also approved and available commercially, is pro-
duced by electromagnets driven by alternating current supplied in bursts
of pulses. Although it ties the patient to an electrical outlet for twelve
hours a day (mostly during sleep, of course), this apparatus completely
avoids surgery and its attendant risks.
The funny thing is that all three methods—low current, high cur-
rent, and PEMF—seem to work equally well. Since the FDA approved
them in late 1979, success rates have stabilized at about 80 percent.
As
far as
the
two electrode
methods are concerned,
I
believe some
experiments wedid in
1977 and
1978 revealed why they both work.
When we arranged all the reports in order from lowest current to high-
est, we found a narrow band of low amperages and a wide band of higher