Attorneys for Dawn Bradley filed the lawsuit in Indio, Calif., on Thursday. Bradley claims she was seriously injured during a December altercation with the 25-year-old Lohan.
A full copy of the suit was not immediately available.
Steve Honig, a spokesman for Lohan, declined comment
Bradley's attorney Owen McIntosh says his client requires surgery on her wrist because of the injury.
Bradley, who is also known by her married name of Dawn Holland, was fired from Betty Ford Center after discussing the incident with Lohan on camera with celebrity website TMZ.
Prosecutors in Riverside County, east of Los Angeles, declined to charge Lohan with battery.
