For nearly 30 years Ion Popescu was a heavy drug user, and the scars of his decades-long addiction remain very visible today. After being hit by a train in Moscow while using drugs, Ion now walks with a limp and the help of a crutch. A deep scar runs along the right side of his face, a reminder of the surgery that removed parts of his jaw due to osteomyelitis, a bone infection common among people who inject drugs.