Hi zisuer
Have you read this study regarding cervical traction:
PEDro - Detailed Search Results
I think this may be the only solid evidence for a treatment for Thoracic Outlet Syndrome and I don't think there are any specifically for the diagnosis of cervical rib - so it depends how your patient presents.
The only think I would add is that the authors conclude that hot pack and exercise was beneficial - because the control group got this and they got somewhat better whereas the experimental group got this + cervical traction and got a whole lot better. So if one goes of the between groups comparison which is the important part: it is the cervical traction that really improved matters where as the heat and exercise may or may not have a placebo or were going to get somewhat better anyway- we don't know