The University of Wisconsin football team's defensive line ranks got even thinner Tuesday, and there's a chance they could stay that way for the rest of the spring.

Senior defensive tackle Mike Newkirk, one of the last standing inside players with much playing experience and a projected starter at left tackle, missed the second spring practice with a left shoulder injury.

He is awaiting test results in the next two days to determine if he will need surgery.

Newkirk originally suffered the injury last fall but played through it, starting all 13 games — 10 at left end and the final three at left tackle.

He aggravated the injury about a month ago while lifting weights and again during the first spring practice Saturday.

"What we're doing, we're just making sure everything's all right and looking at it, make sure we do all the tests," UW coach Bret Bielema said. "If he does have to have surgery, we're going to do it sooner (rather) than later, so he can be involved in everything in summer conditioning."

If that were to happen, Newkirk would be the fifth player — and third returning starter — on the defensive line since the middle of last fall to undergo surgery.

Sophomore defensive end Kirk DeCremer underwent back surgery two months ago and senior defensive tackle Jason Chapman underwent knee surgery in November.

Bielema also updated the condition of two other defensive tackles who have been out with injuries.

Junior Dan Cascone had shoulder surgery at the end of the 2007 regular season and missed all of the bowl practices. He hopes to be cleared to return for summer conditioning.

Sophomore Brandon Hoey missed all of 2007 after undergoing back surgery midway through the season and it is serious enough it could be career ending, Bielema said.

That left junior Jeff Stehle, who had limited snaps last season, and redshirt freshman Patrick Butrym as the tackles on the No. 1 defense.

They were backed up by redshirt freshman Jasper Grimes and fifth-year senior Joshua Neal, a converted linebacker who still wears No. 48 and is listed at 5-foot-10 and 250 pounds.

Junior college transfer Dan Moore eventually could provide some help inside but he's been working at right end with the No. 2 defense.

"Dan Moore has been very impressive since he got here," Bielema said. "(Tuesday) was a lot better than Saturday. I think Saturday, all of the (new players) were kind of wowed from the speed of the game and the tempo."

Injured help out

The injured players who aren't practicing this spring also include tight ends Travis Beckum (shoulder) and Garrett Graham (shoulder) and cornerbacks Allen Langford (knee) and Aaron Henry (knee).

"What I've really been pleased with these first two (practices) is the way the guys that aren't involved, are staying involved," Bielema said. "That's a hard thing to do."

Bielema urged his assistants to keep the injured players a part of things. Langford could be seen frequently helping the freshman defensive backs, while Beckum and Graham were carrying around clipboards.

"Hopefully, they're telling (young players) the right things, but at least they're into it and staying involved," Bielema said. "That's a positive for us."

Anderson bulks up

Sophomore receiver Isaac Anderson, who has been plagued by hamstring injuries the last two years — causing him to be redshirted last season — has gotten off to a good start.

He has added some strength and weight — he's now listed at 5-11, 177 pounds — which Bielema hopes will allow Anderson to finally stay healthy.

"Physically, he hasn't been able to hold up," Bielema said. "That's a big thing that's gone through his mind and us as coaches, he's got to put himself in a position to show us he's got some durability. Hopefully, with this weight, just little things you saw out there (Tuesday), I think, were positive signs."