Well, it does contain mitragynine, which is a prodrug
[ref] for 7-hydroxymitragynine which rearranges to
mitragynine pseudoindoxyl, which is the active opioid in question.
[ref] Kratom is well known for substituting for opioids.
It should help you, that is, as long as it contains actually active kratom. (sometimes commercial kratom capsules contain low quality/old material that may not be very active) Although it is not as potent as a hydrocodone pill, and you may need to take quite a few capsules: a "stimulating" dose is anywhere from 1 to 5 grams of the crushed leaf, and sedative effects may need 5 to 15 grams.
It is usually better to find a supplier for the crushed leaf and cap it yourself, the fresher the better. Strain does not seem to matter much; in my analysis they mostly contained similar alkaloids. (BL does not allow posting sources or discussing them in PM though).
I myself have used kratom, usually at the 10-15g level, for painkilling purposes. Aside from needing to consume large amounts of bitter leaf, it was quite effective. I actually purchased mine from a funky ethnobotany store within a sort of headshop, locally.