"So far the series has been everything I had anticipated and knowing I'll play no further part is quite hard to take.
"Given the way we had started the series I was looking forward to playing a leading role in England retaining the Ashes but that's not to be.
"Injuries happen and there's nothing I can do about it other than make sure I get stuck into rehabilitation and come back stronger in time for the World Cup next year.
"This winter is a big one for the England team so my focus will have to shift to preparing for the World Cup."
England captain Andrew Strauss told BBC cricket correspondent Jonathan Agnew that Broad's loss was a huge setback for the team.
Tim Bresnan Age 25, Tests 5 14 wkts at 35.14, 125 runs at 41.66; Total first-class wkts 256, av 32.26; Runs 2918, av 27.52
Ajmal Shahzad Age 25, Tests 1 4 wkts at 15.75, 5 runs at 5.00; Total first-class wkts 94, av 32.54; Runs 814, av 29.07
Chris Tremlett Age 29, Tests 3 13 wkts at 29.69, 50 runs at 12.50; Total first-class wkts 344, av 27.24; Runs 1884, av 18.29
"It's a big blow there's no doubt about it," Strauss reflected. "He's been the mainstay of our bowling attack with Jimmy [Anderson] and Swanny [Graeme Swann] for a while now and hasn't got what he has deserved on this tour. It was terrible news and we're all really sad for him."
England's chief medical officer Dr Nick Peirce said Broad would return home to begin rehabilitation.
Broad struggled for form in the first two Tests, but was expected to be a key player in the series as part of England's four-man front-line bowling attack and with his ability to score major runs lower down the order.
The tourists are not short of bowling cover down under, with Ajmal Shahzad, Tim Bresnan and Chris Tremlett vying to take Broad's place in the third Test in Perth starting on 16 December.
And former England captain Michael Vaughan believes Hampshire's Tremlett, who has played three Tests and impressed in the warm-up game against Australia A in Hobart, is the current favourite.
"It will be a shoot-out in Melbourne [England's game against Victoria starts on Friday] between Shahzad, Bresnan and Tremlett," Vaughan told BBC Sport.
Moxon backs Yorkshire pace duo
"I just hope they pick the guy they think will take the most wickets in Perth. Bresnan is probably the best batsman, and if he bowls the best in Melbourne, then he will play.
"You would think it may bounce in Perth, so I think Tremlett has just got his nose in front. But don't rule out Bresnan. I think he is an ever-improving bowler.
"Shahzad will come into play if they believe it will reverse swing, but I haven't seen much reverse swing in Perth. So it's probably between Tremlett and Bresnan, with Tremlett just ahead at this stage."
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