View Full Version : Summary : Indwelling Electrodes for the Anconeus in Throwing

08-11-1998, 11:00 PM
Thanks to all who responded to my original and subsequent post regarding indwelling electrodes for the anconeus muscle during baseball pitching. Several people (Larry Fennigkoh, Patrick Boissy) suggested surface emg and that may be done as a later comparitive study. Special thanks to Dan Antonelli, Robert Hintermeister and especially Carlo De Luca. All recommended fine wires that can be made or purchased. We settled on a product from Nicolet. Details are in the reponses listed below.

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Dear Dr. DeLuca:
I am working in a clinical setting where a physician (ortho. fellow) wishes to insert electrodes into the anconeus to monitor it's activity during throwing. I have worked predominatly with isometric surface emg so this is beyond my area of experience/expertise. Do you have any suggestions/recommendations as to the type of wire/needles that may be used in this case?

Do not use needles. For wire electrodes use platinum wires which are coated with teflon.

Also what would be the likelihood of movement problems using indwelling as opposed to surface electrodes in this type of application? I am unaware of studies that have rigorously examined this issue.

Stabilize the wire electrodes by placing barbs at the end of the wires. expose approx i mm of the wire at the tip to increase the pick up area of the electrode and, thus making it less sensitive to movement. I am not aware of rigorous studies which have investigated the effect of movement on the stability of the EMG signal from different electrode types during dynamioc contractions. There are some old studies which have looked at isometric contractions -- i do not remember where they are now.

Would a comparison in this case be a worthy contribution to the field at large? My suggestion would be to isometrically test the muscle with both kinds of electrodes and then compare the activity to the dynamic case.

Yes, I would encourage you to perform this study.

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Interesting question, but it is not the proper direction. WIRE electrodes
should be used. They can be made following the directions given by
Basmajian using 50 micron nylon coated 800 ohms per inch wire called
stablohm wire. 3mm of wire should be bared with a pair of wires inserted
using a #25 gauge needle and a one inch diameter loop on the surface of the
skin with a small piece of tape place proximal to the loop to hold it in
place. The loop allows the wire to move through the tissue and keeps the
barbs (bared wire) in place in the muscle.

Hope this is of some help.

Dan Antonelli - Childrens Hospital Los Angeles & USC Biokinesiology
Dept. dantonel@hsc.usc.edu

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Dear William,

Basmajian & DeLuca recommend platinum/irridium or stablohm (stainless
steel) fine wire. We tried both and found the Stablohm to be stiffer and
had no problems with breakage as with the softer P/I. Stablohm is
significantly less expensive also. California Fine Wire is a good source
for the wire.

Getting reliable signals with intramuscular electrodes is tricky business.
Having a pre- and post-test standardized measure (MVC) within 2 standard
deviations of one another is one way to insure that the signal has remained
consistent over the course of your dynmamic muscle activity. You may have
to discard data to meet this criteria, but at least this increases your
chances of having reliable (reportable) data. Good Luck!


Robert A. Hintermeister, Ph.D.


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You mean fine wire electrodes, I assume. Needle electrodes can be
quite painful as they can tear muscle tissue as the fibers contract.

We have a publication about the placement of fine wire electrodes in
the forearm (where many small muscles are tightly packed), which
describes techniques to help you place the electrode in the muscle of

Burgar CG, Valero-Cuevas FJ, Hentz VR. Improving selectivity of
fine-wire electrode placement for kinesiological and clinical studies:
Application to index finger musculature. American Journal of Physical
Medicine and Rehabilitation, 1997;76(6),494-501.

Hope this helps,

-Francisco Valero-Cuevas

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Francisco Valero-Cuevas, PhD

Research Associate and Lecturer Biomedical Engineer
Biomechanical Engineering Division VA Palo Alto HCS
Mechanical Engineering Department Rehab. R&D Center (153)
Stanford University 3801 Miranda Ave
Palo Alto, CA
(mailing address)

(650) 493-5000 ext 66254; (650) 493-4919 FAX
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Have you considered fine wire electrodes instead of needle electrodes? They
are inserted into the muscle using a needle, but then the needle is withdrawn.
They might be more comfortable in a dynamic task than a needle electrode, and
they have the specificity that a surface electrode cannot achieve. However,
I'm not sure if they are commercially available. Might want to check the
biomech-l archives, I seem to remember that fine wire electrodes were
discussed in the past. Sorry, I don't have any information on needle
Anne Hines

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Dear Mr. Sloboda -

I'm a graduate student in the Motor Unit Laboratory at the NMRC. Dr. De
Luca has brought to my attention your interest in Fine Wire EMG recordings.
The wire we have been using for the Upper Trapezius Muscle and the FDI is a
nylon coated platinum wire of 0.002 inch in diameter (California Fine Wire
Company). The ends were exposed by simply pulling on the nylon coating with
tweezers and cutting the barred ends to 1cm length. We have obtained good
results with this kind of electrode, but for larger muscles larger diameter
fires may be selective enough.

If you have any further questions, feel free to contact me directly at the
address below.


Alexander Adam
__________________________________________________ __________________
Alexander Adam
Graduate Student, Biomedical Engineering e-mail: aadam@bu.edu
NeuroMuscular Research Center Phone: (617) 353-9634
Boston University Fax: (617) 353-5737
44 Cummington St. Office: ERB 521
Boston, MA 02215 Lab: ERB 510

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The anconeus is a superficial muscle that can be easily recorded with
surface electrodes. For an activity like baseball pitching, needle
electrode EMG would, depending on what you are looking at, be an overkill.
Furthermore, motion artifact would be difficult to control.

(Patrick Boissy)

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Hi William: Yes, you could use needle electrodes, but why? Does the nature of your questions preclude the use of surface electrodes?
You may wish to review Basmajian's "Muscles Alive" text for more information. Good luck.
Larry Fennigkoh, Ph.D.

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I have done some work with electrodes described in a paper by basmajian
and stecko
I think in the late 60ies.
You take two very thin and insulated wires , push them through a
hypodermic syringe,
remove the insulation from the tip of the wires. After insertion you
simply remove the needle, connect the outside end of the wires to a
preamplifier, stick tap all over the
place so that the wires remain in place. With some fiddling you will be
able to get a signal.


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I use fine wires and follow procedures outlined by Perotto (1994). The
forearm fully pronated & elbow at 90 deg of flexion, placetip of the little
finger on the olecranon and ring & middle finger along with ulna. Insert
needle just beyond tip of middle finger, just radial to the ulna. I've done
this with throwing & if you use a high pass filter to clean up your movement
artifact it works nicely. I'm out Thursday & Friday, but if you need more
info have Glen to call me on Monday. Good luck.


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William M. Sloboda
American Sports Medicine Institute

Thanks to all who responded to my original and
subsequent post regarding indwelling electrodes for the anconeus muscle during
baseball pitching.  Several people (Larry Fennigkoh, Patrick Boissy)
suggested surface emg and that may be done as a later comparitive study. 
Special thanks to Dan Antonelli, Robert Hintermeister and especially Carlo De
Luca.  All recommended fine wires that can be made or purchased.  We
settled on a product from Nicolet.  Details are in the reponses listed
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