Safina, who topped the WTA world rankings for 25 weeks between April 20 and October 11, 2009 and then returned to top spot for just a week on October 26 before Serena Williams monopolized the position for nearly a year, has not played since early May.
The 25-year-old Muscovite will therefore will miss her third successive grand slam tournament at the U.S. Open, after also pulling out of the French Open and Wimbledon. In 2010 she also missed Wimbledon while losing in the first rounds at Roland Garros and New York.
Safina currently stands in 65th position on the WTA rankings and using her official website www.dinarasafina.com," she said: I'm sorry to report that my back is still acting up and I will not be able to play until at least the end of the year.
After missing much of last year, she made a comeback at the Australian Open in January but suffered an embarrassing 6-0 6-0 defeat by Kim Clijsters in the opening round and soon after contemplated quitting the sport.
Earlier this year, Russian media quoted Safina as saying: I don't know how long my time out is going to last because I don't want to torture myself and my body anymore.
Despite previously holding the top ranking spot, she had failed to win a grand slam title, losing all three of her major finals (French Open in 2008 and 2009 and 2009 Australian Open).