Joy
A C7 transfer (which I've had: 4 months after injury over 5 years ago) will not do anything different to the muscle than any other nerve transfer will as far as revitalizing a chronically atrophied muscle.
Your doctors should of told you, or it's very easy to research this online, that a muscle can only be viable for re-innervation at a maximum of 2 years, even barely after a year. Most surgeons used to wait six months to operate to allow for natural regeneration of injured nerves, now they are waiting 4 months maximum and a lot of times performing nerve transfers as soon as possible (with in hours or days).
It sounds like your sons option for any functional return or use of his arm would have to include muscle transfer AND a nerve transfer (from somewhere) to produce neural impulse for the transfered muscle to function. Unless he has muscles that are only barely working than an option may be to do a nerve graft (replacing a section of a damaged nerve).
I don't know the specifics of your sons injury, but if you are in Ireland, I'd be heading to the UK. There are many good specialists there that are on the cutting edge for Brachial Plexus Injuries.
Dr. Thomas Carlstedt
http://www.snowsportsinjuries.co.uk/dr_ ... stedt.html
http://www.londonnervecentre.co.uk/thomas_carlstedt.php
Dr. Rolfe Birch
http://www.ucl.ac.uk/orthopaedics/centr ... nits.htm#p
Peripheral Nerve Injury Unit:
Professor Rolfe Birch
Professor of Orthopaedic Neurological Surgery
Tel: (+44) 020 8954 2300, Extension 5803
Professor Thomas Carlstedt
Professor of Peripheral Nerve Surgery
Tel: (+44) 020 8954 2300, Extension 5803
Dr. Simon Kay
http://ubpn.org/medicalresources/uk-bpi.html
These doctors are all leaders in the field and have been specializing with BPI for years and years.
If you do want to venture to the USA, I'd highly recommend the Mayo Clinic:
http://ubpn.org/medicalresources/mayo-contact.html
If your sons muscles are beyond repair (over 2 years without nerve connection) then his only option may be a muscle(s) transfer. I had a Gracilus muscle from my thigh transfered to my biceps region to help assist my existing biceps muscle that was in need of re-innervation as well. Intercostal nerves (from my ribs) were transfered to innervate both the Gracilus muscle and the existing biceps
My C7 transfer went to my deltoid to hold my shoulder in place. It works for that purpose (barely) but not much else. It is not functional for much else, as I can lift my arm about 15 degrees from my side, but don't have much control over the rest of the arm to make it have any real function. It is basically an alternative to fusing the shoulder, which I've considered for many years regardless.
If it has been 6 years, there is NO RUSH. Besides your sons own desire and need to get as much functional return as possible. But as far as a time line goes for surgeries having to be performed before things waste away beyond reproach, it is to late for that, and it is time to simply make the wisest choices possible.
If I was in your sons shoes, I'd visit one of the UK specialists listed above, and ask them straight out, "do you know anyone else that can provide more useful functional return than what you are offering?" Ask them about the Mayo Clinic, they should know. Those doctors in this specialty know each other's work and often refer each other (mind you, this is only the top doctors that do this, they have more than enough work load).
I wish I could give you the answer you and your son want to hear. As it stands there is no therapy available yet to revitalize chronically atrophied muscles. There is research going on in this field, so the future may offer hope. I wish you both the very beast!
Best of Luck,
Christopher