"The operation went okay and when I spoke to the surgeon afterwards he seemed happy. I'm not in that much pain at the moment, which is surprising, and I'm able to walk on crutches," said Gerd.
"I've been told to take it easy and just do nothing for the next two weeks. After that it will just be a case of strengthening the knees again and then building up my fitness.
"My season is definitely over though, there's no doubt about that. It's frustrating but to be honest it's a problem that has plagued me since the summer and I needed to have the operation.
"I'm gutted to be missing out the Champions League because with Nando ineligible there may have been a chance for me to play. But given the circumstances it wouldn't have been fair on the club or myself because I wasn't fit enough.
"If I'd have waited until May for the operation then I would have probably missed the start of next season. As it is my aim now is to push on and get myself ready for the start of pre-season training in July."