Team physiotherapist Kevin Sims said: "Peter Siddle developed some back soreness late in the first Test against the West Indies and scans conducted in Trinidad showed the early signs of a low back bone stress injury.
"He was subsequently ruled out of the second Test and after further consultation we feel that to prevent this injury developing any further it is in Peter's best interest for him to return to Australia to rest and for appropriate physiotherapy to ensure he is fully fit when next selected for Australian duties.
"James Pattinson had an episode of acute low back pain after fielding and throwing awkwardly late on day three of the second Test. We have since monitored his condition over the last couple of days and the initial investigations suggest that while the injury is not serious there is insufficient time for him to recover to play in the third Test match.
"As such, we have today made the decision for James to return to Australia to prevent this injury developing any further and for him to receive the appropriate medical and physiotherapy management." Australia, who won the opening Test, will not send replacements out to the West Indies.