The Lions earlier this month released Raiola's linemate, guard Stephen Peterman, who had started 48 straight games for Detroit, in a cost-cutting move.
Peterman was released along with defensive end Kyle Vanden Bosch and receiver Titus Young in moves that cleared $8 million-plus in salary-cap space, although the Lions have acknowledged that Young, now with the St. Louis Rams, was cut mainly because he was a distraction.
The Free Press, which reported that Raiola would have counted $6.1 million against Detroit's 2013 salary cap, reported the center's decision to restructure, citing a person familiar with the agreement. The newspaper reported that Raiola's new '13 cap figure is unknown.
Raiola, 34, has played 12 seasons for the Lions, starting 172 games after being selected by Detroit in the second round of the 2001 draft.
Lions general manager Martin Mayhew has said he hopes to extend quarterback Matthew Stafford's contract this offseason for short-term help with the salary cap and a long-term gain with the leader under center the Lions have needed for decades. Stafford signed a six-year deal in 2009 with $41.7 million in guarantees that was worth as much as $78 million.
Information from The Associated Press was used in this report.