Use google to find the worker's comp laws for your state. Once you understand them, look for an attorney. Your research should give you a good idea of the settlement that you should get (my state has specific amounts for the body area and % of restriction.) Attorneys typically charge a contingency. If your doctor is saying you can no longer preload and that is supported by the comp Doctor (not very likely, but it does happen), you do not need an attorney. Your settlement will be based on state guidelines (if your state has them) and an attorney is just going to draw out the process.
If you decide that you do need an attorney, you need to decide whether to hire based on contingency (you will give up 35ish% of your settlement) or pay the attorney pay the hour for the work he/she does. I would ask, up front, how many hours they typically bill to a comp case. Some simple math will tell you which option to go with. Do keep in mind, that if you go hourly, you will have to pay a retainer. That could be as much as $5k. Typically, that is why comp cases are handled on contingency.
From what I have seen, people that do not have lawyers end up proceeding through the whole deal much faster than those that do not. From the outside, looking in, it also does not appear that having an attorney gets the employee a larger/better settlement.