Changing the rotation of a bone's axis?


I had the following problem:

As the bone was extruded that way by restricting the extrude to the Y-axis, it turned out to have its axis in a rather arbitrary rotation. My workaround was to delete the bone and just create it newly (and reconnect child bones). Is there a better way to do that? I tried to rotate the bone in edit mode, but i can’t rotate it around the axis necessary to correct that rotation, so that failed.

Ctrl-N, or in the Properties tab (N) you can input numerals.