Orif&im nailing of tibia 4months.little pain in ankle while walking.but when hang leg for 2hours or more ankle swell a lot.is it bad?what should do?

Move more often: It can take up to 12 months for some injuries to fully heal, and your description suggests there is still inflammation or other issue to be resolved by your body. You are just highlighting it with the added stressor of hanging position (=more gravity and pressure near knee to slow blood return=swelling). Try to change position more frequently to reduce occurrence.