Similar injuries have long plagued Spears, who had to postpone her "Sometimes" video shoot after twisting her knee back in 1999. In March of this year, she was forced to cancel two concerts because of her knee.
"Outrageous" is the fourth single from Spears' multi-platinum In the Zone CD. Her Onyx Hotel tour is scheduled to return to the U.S. June 22nd in Hartford, Connecticut. Contrary to our previous report, there is no word yet as to how the injury will affect Spears' tour plans.