As noted, Randy Orton vs. Bray Wyatt will not take place at WWE Backlash tonight as Orton still has not been cleared for action following his TKO loss to Brock Lesnar at SummerSlam on August 21st. PWInsider reports that Orton's issues appear to be concussion related, indicating that he has not passed an Impact concussion test.
There's still no word yet on how WWE will handle tonight's match with Wyatt but Orton is backstage at the pay-per-view in Richmond. Kane replaced Orton at a weekend live event in Raleigh, North Carolina, picking up a win over Wyatt. Dave Meltzer of F4Wonline.com notes that Kane would be the likely Backlash replacement for Orton, unless a surprise was done.
As noted, the Orton vs. Lesnar rematch set for later this month at the non-televised WWE live event in Chicago is also up in the air. Meltzer adds that there's no confirmation on Orton's injury but he took a legitimate beating from Lesnar last month. WWE officials were hoping Orton would be cleared over the past week but he was not.