Dean Goodman from Reuters is reporting:

Here’s AEROSMITH by numbers: The veteran rock band has performed seven shows on its summer tour, but now two of its five members are on the sick list forcing the postponement of at least three shows. In the latest development singer Steven Tyler, 61, has been hobbled by an unspecified injury, putting the kibosh on Cincinnati (July 1), Hershey, Pa. (July 3) and Virginia Beach, Va. (July 5).

Guitarist Joe Perry sent out a Twitter message on Friday expressing “sincere apologies,” and asking fans to pray for Tyler’s speedy return. “It really bums me out too - you have no idea,” he said.

The tour was looking shaky before it even started in St. Louis on June 10. Guitarist Brad Whitford, 57, underwent surgery earlier that month after hitting his head while getting out of his Ferrari. He is scheduled to rejoin his bandmates in Raleigh, N.C., on July 7, assuming Tyler is back in the saddle by then.

The band says the three shows (so far) will be rescheduled. Dates are on tap for the North American trek through Sept. 16 in Detroit. The band’s publicist was unable to provide additional information about Tyler’s health.

Fans have said Tyler appeared to pull a leg muscle at the band’s last show, on Monday. Tyler has been troubled by his feet: In May 2008, he checked into rehab saying he needed “a safe environment to recuperate” following a series of painful foot surgeries. In 2006, the band was forced to cancel the remaining dates on a tour so that Tyler could undergo throat surgery.