If it was 10-9 round in favor of fighter A before the knockdown, then after the knock down it would be 10-9 in favor of fighter B who knocked the other fighter down. One point deduction from fighter A who was winning the round before the knockdown and add one point to fighter B, who knocked the fighter down.

If it would have been a 10-8 round in favor of fighter A before the knockdown then just add 2 points to fighter B to make it 10-10?