This is an off topic question. But I am an atty, who did family law (until
my oldest was born 16 yrs ago). So from a worker's comp perspective:

If your doctor has done the MRI and blood tests and just says arthritis,
they aren't seeing a red light flashing to point toward one of the over 100
different specialized kinds of arthritis. You might want a Rheumatology Doc
(RD, not RA. RA is short for Rheumatoid Arthritis - the disease) to screen
it for your own treatment. But unless you are claiming that your arthritis
was cause by repetitive strain of the job or injury, you want to keep the
arthritis some what separate from your worker's comp diagnosis because if
they say some of your injury/incapacity is from arthritis, the WC board will
say its pre-existing  which reduces what is worker's comp's responsibility
and you get less money. It's only of the injury has worsened the arthritis,
or cause increased pain because of the pre-existing arthritis, that
mentioning the pre-existing arthritis becomes any factor in your case.

Listen to your FP - If your back symptoms include neuralgic pain, then you
need to see a neurologist. They are the ones who will test to see if there
is injury to the nerves, and if yes, whether the injury is permanent - what
you seem to need for treatment, and also for the wc claim. You might also
need to see an orthopedist as part of it. But if your FP is telling you
something, trust and listen to them.

I also advise you to get an atty for your claim. If I'm recalling correctly,
their fee is not taken from your award but from a separate fund within the
worker's comp system, so it won't cost you much of anything out of pocket.
And its been shown that people who are represented on these claims wind up
getting a higher award. I worked for a firm that did tons of worker's comp
cases while I was in Law School. [They maintained a list of doctors to
recommend to clients. Some on the list were excellent practitioners who
really helped their patients. Some on the list were the ones who knew how to
generate bills and records with all the correct buzz words to satisfy the WC
Board, for the clients whose injuries needed less intervention.]

Adelle