Before Hilger was hired by the Philadelphia Orchestra under Leopold Stokowski, the only female instrumentalists with major orchestras were harpists.
The Austrian-born Hilger took her first lessons with Ottokar Sevcik, and then with Paul Grummer at the Vienna Conservatory. She was the youngest member of the Conservatory Orchestra, and made her debut with the Vienna Philharmonic at age 12.
After World War I, Hilger came to the United States with her two sisters and performed around the country as the Hilger Trio before being auditioning for Stokowski in 1934. She remained with the Philadelphia Orchestra until her retirement in 1969.