Sorry to hear about your knee and the symptoms you are experiencing. In general a PCL does not need surgical treatment and most people can do quite well without it.
Your instability symptoms may be due to a new problem in the knee (if you have had another injury), such as a meniscal tear, or from weakness in the muscles stabilising the knee.
It sounds like you need to get you knee reviewed. I would suggest either going back to your original surgeon/physician or you could see a Sports Physician/Sports Physiotherapist for further assessment.
They may rescan your knee as part of this assessment. If there are no further issues with your knee, I would suggest returning to a rehab program with quads and hamstring strengthening and proprioceptive exercises.
Hope this helps.
BW
Dr Dinesh
