Luis Castillo has fractured tibia. Not good. Won't know for sure on his season status until tomorrow.
This is bad news. Just in case you don't know or have forgotten what a tibia is, it is the shin bone. A lot of the times broken bones have easy recover time frames to predict, but I've been told (thanks @injuryexpert) that with the tibia it's too difficult to speculate on a time frame without knowing the extent of the break. So, as Acee says, we'll know more on his status tomorrow.
For now, Vaughn Martin becomes the starter and Jacques Cesaire will back up and rotate for both positions. If Castillo goes on IR or is expected to be out for a while, then we'll see the Chargers bring in a lineman. Ogemdi Nwagbuo could return. They could also get Travis Johnson, but that's less likely since he wasn't in camp with the Chargers or any other team for that matter. Igor Olshansky is still out there is well, but I still think that bridges were burned when he left.