The British beauty was hailing a cab in the French capital when she was violently attacked by thugs, who left her with a torn ligament.
Campbell went to police to report the incident, which happened over a month ago, before boarding a private jet to Vail, Colorado, where she received treatment from a top orthopaedic surgeon.
A source told the New York Post gossip column Page Six: "It was terrifying. Naomi believes the assailant had been watching her, casing her out, and waited for a moment to strike when she was alone. She was attacked in the street as she hailed a cab, and robbed.
"Her leg was injured as she was violently pushed to the ground. She was understandably very upset and shaken up."
Campbell was first spotted using a wheelchair last month but she has kept quiet about how she was hurt.
She is now believed to be recovering in Miami, Florida, ahead of the launch of her new TV show The Face next month.