I Had Spine Surgery 4 Months Ago.immediately Following Surgery I

I had Spine surgery 4 months ago.immediately following surgery I was having probles with my left knee and kept falling down on my knee was buckeling. Before surgery,,i had no problems and I had an MRI and was told I have a lot of debris in my kneecap as well some arethusa. could during the surgery something happened to my leg that could case this.