The 26-year-old suffered a cruciate knee injury during Saturday’s win over Middlesbrough.
“Peter will have to have an operation on his cruciate ligament and unfortunately it looks as though that’s him for the season,” said Rangers boss Neil Warnock.
“I feel so sorry for him, he’s an important part of the squad. It’s disappointing for the lad, he’s distraught but he’ll bounce back.”
