Webster has played just one match since his move to Ibrox

The Scotland international suffered the injury in the first training session following his loan move from Wigan.

The 25-year-old recovered and made a scoring debut in the 4-0 win over Gretna on 1 September but an ankle injury saw him sidelined again.

However, the knee injury is still causing concern and he may have to go back under the knife.

Ibrox manager Walter Smith said: "There is a little bit of cartilage causing him a problem and he may need to go back in and get it tidied up.

"It's the knee he had the operation on in January. He had done the rehab, then damaged his ankle ligaments, was out for six weeks, now he has come back and is getting this pain again.

"He has not had the best of luck because, although it's a straightforward tidy up, you are looking at another four or five weeks before he is back again."

Meanwhile, fellow defender Stevie Smith is also facing the prospect of more surgery following two operations on the pelvic injury that has kept the 22-year-old out of action since December.

"Stevie's still having a problem. He has been at a specialist in Germany and we are waiting on the results," added the manager.

"It might be he will need another operation on his hernia because it has been causing him a bit of bother.

"The frustrating thing is he has done all his rehab fine. It's just in games when he kicks a ball that he is getting a problem."