It sounds like he is using opioids from what you are saying and they are not working. Personally, I find them so disagreeable that I would rather be in pain if those were my only choices.
The number one thing to do about pain is to remove the cause, but if you are concerned about pain after surgery, that is not relevant.
I think we talked about inflammation under a different topic. The more you control inflammation the better. Usually stopping the cause if you can. If you can't using other methods to decrease it such as foods, herbs, supplements, meditation etc. Using methods to support a parasympathetic state in the body allows it to rest and heal. Many mind/body activities that promote being in the moment and supporting relaxation can support a parasympathetic state.
Things to consider for the pain:
acupuncture
bodywork
nutrition
hydrotherapy
herbs
homeopahty
flower essences
fasting
mind/body training to go beyond pain
When pain is due to something traumatic such as happens in an accident or surgery, using methods to assist healing in the area and promote blood and lymph flow in the area are helpful. They should be okayed with the surgeon/primary care practitioner to find out when you can start them. These would be hydrotherapy, counterirritant herbs used externally in the area, herbs that help to move stagnant blood internally, homeopathy.
Depending on what the surgery is for and the outcome of the surgery can change what might be used also. There is homeopathic Arnica or Bellis that often gets used immediately after a surgery the same way it would be used after other traumas to the body. However, after that what would be used would be specific to the reaction to the surgery. Does the pain have a big nerve component to it and if so, Hypericum or St. John's wort is helpful in fresh plant tincture form. Is there damage to ligaments then Ruta homeopathic is specific. These are just a few things that might come up. However, you don't know until you are at that point in time. These treatments are also healing, not just for pain. Sometimes people just go for the pain in general and use anodyne herbs, which does not do anything but numb the symptoms, however if pain is intense and you can't get it down, it becomes hard to heal. There are many herbs used for pain and they are categorized into different groupings that relates to bodily processes that are related to the pain. They may be circulatory stimulants, anti-inflammatories, muscle relaxants, nervine sedatives, anodynes, vulneraries,
local counterirritants, Anti-edemic and Adaptagens and nutritives.