I gather that the incision for a brachioplasty can be on the inner arm or the back of the arm. If the latter, is the scar dead centre down the back of the arm or more to the side where the inner arm meets the back of the arm.

In plastic surgery- scars are least conspicuous when placed in natural border between aesthetic subunits. The best place for an arm lift scar (in my opinion) is in the groove between the biceps and triceps muscle on the inside of the arm. Scars on the back of the arm are very conspicuous.