LATROBE — Pittsburgh Steelers right guard Darnell Stapleton was scheduled to have arthroscopic surgery on his left knee today and the team has no timetable set for his return.

The 6-foot-3, 305-pound Stapleton had been practicing at center in place of Justin Hartwig, who arrived at training camp with a toe injury. But Stapleton had swelling in the knee and has not practiced since Sunday.

"We'll see where we're at after (this) morning," Steelers coach Mike Tomlin said. "We're going to clean it up and go from there."

Stapleton, who made the roster in 2007 as an undrafted free agent out of Rutgers, started the final 12 regular season games and all three playoff games at right guard for the Steelers after Kendall Simmons went down with a torn Achilles tendon.

Notes: Wide receiver Hines Ward and tight end Heath Miller returned to practice Thursday.