Hydrocodone is the narcotic component in Lortab. The law doesn't say how much he can prescribe, but doctors are watched carefully to make sure they are screening patients who get narcotics carefully to make sure patients aren't abusing or reselling them. Hydrocodone is a fairly weak narcotic, effective against mild to moderate pain. It is recommended that an adult not take more than 70mg of hydrocodone/day--which would be 7 Lortab 10/400. The danger in that dose is more from the APAP (Tylenol) in it than the hydrocodone. In short, Lortab is simply not likely to help you in any dose and your doctor is irresponsible to give you any at all, IMO.
Lots of things need addressing, here. What you are having is chronic pain--which is different than acute pain both in QUALITY as well as quantity. Lortab is GREAT for acute pain, but all but worthless for chronic pain--in any dose. What, besides Lortab, are you doing for your chronic pain? How much physical therapy did you have after surgery, and will your insurance company pay for more? Have you tried a TENS unit or ultrasound? Both of these are available for you to do yourself at home and both have helped many people cope with chronic pain. Also, a good relaxation program usually helps bring the pain down as well. Tricyclics, often on-label for depression but NOT ALWAYS--one of the most common tricyclics is cycobenzeprine--brand name Flexeril, and on-label for muscle relaxation, often make a great deal of difference improving chronic pain, especially at night when they can ease the pain and help you sleep. They do usually take 1-3 weeks to work and you do have to take them every day.
If all of the above have not been tried, you should not be given any narcotics for chronic pain--even 3 Lortabs/day.
Now that I've pissed you off--Lortab is among the least effective narcotic pain medicines. It is the same medicine as Vicoden, and it is GREAT for getting high, which is why it is so often abused. That's probably why your doctor is telling you he can't give you more. Most people who take hydrocodone for pain keep taking it to get high after the pain is gone. I'm not saying you are, I'm saying that it's a bad medicine for the kind of pain you're describing, and clearly the doctor you're seeing is not a pain specialist. If, after you are using all of the above, you still have pain that prevents you from doing the normal activities of daily living--that's what the rule is, you know, not "do you have pain" but "how much is it interfering with activities of daily living"--find a pain doctor. They are trained to treat pain and are less likely to prescribe based on fear that the DEA will take their license away for prescribing pain medication because pain docs are expected to prescribe pain medicines. They will help you maximize the pain relief you get from non-drug methods and, if you still need it, prescribe strong narcotics that will help get your pain level down to a level where you can participate in daily life again. If he does this, you will sign a pain contract that will obligate you to follow rules like briinging you med bottles in a certain number of times so they can count your pills and confirm you are taking them as directed and take regular drug screenings to confirm you are taking prescribed meds in the correct amounts and not using any illegal drugs, etc. No, the law does not say you can only have 3 Lortabs a day. Your primary care doctor is unlikely to give you any more than that and you should thank your lucky stars if he gave you that much more than 2 or 3 times. A pain doc can give you any amount of any drug he feels will improve your activities of daily living, but you have to be in a pain program, and that requires you work hard on both drug and non-drug methods of improving your life.