Could Cold Feeling In Leg Post Twisting Of Knee Be Due To Vascular Injury?

Hi there..my 23 yr old son was workung a valet job and twisted his knee we applied cold and elevated it for 48 hrs...he has minimal swelling but pain is at a 5 at rest if he puts weight on it it is a 7. On a scale from 1 to 10...we went ER he was given a knee stabilizer and crutches on the day of the injury....we returned to ER today because his leg is cold...they did arterial doppler and said it was negative. But to fillow up with orthopeidic to make sure there is no vascular injury??