a few with Thoracic Outlet Syndrome {TOS} have had winging scapulas.
I know one had surgery to fix hers but she doesn't post a lot now.
as far as the TENS for it i don't know about it.
Did a dr or PT suggest the TENS for that use?

I thought the TENS was more for nerve/pain relief than working the muscles.

You might want look into an Inferential stimulator or even a muscle stim

as each works a bit differently.

here are some links that explain and have more e stim info on all the types and uses.
Electrotherapy
http://www.vitality-web.com/backstor...Stimulator.htm
http://www.medi-stim.com/overview.htm
http://www.rehabpub.com/features/82004/3.asp
http://www.spine-health.com/topics/c...ctro/el01.html
http://www.skylarkdevice.com/web-site/ele_thera.htm
http://www.bmls.com/electrodes/epc.php
http://rehabilicare.com/protocol.html