What surgery do I need for pinched nerve in my arm?

It depends on nerve. The most common arm compressions are carpal tunnel ( median N at wrist) cubital tunnel (ulnar N at elbow) and less commonly guyon canal (ulnar N at wrist). Each requires a decompression surgery. Carpal tunnel involves opening the flexor retinaculm, and can often be done by scope. Cubital tunnel requires open surgery and often replacing the N in its canal. Steroids and PT may prevent surgery.