Just for good measure...Rehab process for an ACL reconstruction will include swelling and pain.
The body heals by naturally producing scar tissue (internally) and scabs (externally) to patch/protect and repair itself. After long periods of immobilization and weight restriction, scar tissue has to be exercised and released (torn), in a systematic and progressive plan. Normal swelling and irritation results from the normal rehab process. There's a fine line between progress and re-injury. Think of a two steps forward, one step back until pain and swelling is controllable. Then, a final approach includes stacking pain free, no swelling workouts to go with increased strength and mobility.