pcl replaced 3 yrs ago

by paul
(wales)

I had my PLC replaced 3 years ago, my post rehab went well and I couldnt wait to play sports again. I took my time the first 5-6 months of training, but when I stepped it up a little bit more, I got a slight pain in the middle of the knee for 2-4 of days after training, then the pain would go. My Knee is stable and feel ok to do day to day things so I am happy with that. Any one have any idea what this pain could be please?