Welcome to the forum.
I hope you're not experiencing much pain or discomfort.
It sounds complex, however, it's just medical terminology meaning that
your knee cap is pulling off to the side (under load), instead of following its up and down track on the femur bone upon bending and straightening.
There's also loss and splitting or cracking of the articular cartilage ( the soft cushioning protective tissue between the femur, the knee cap -patella- and the tibia bone, which are the bones involved in the knee structure).
This is attributed to moderate degenerative disease, meaning that there's no specific diagnosis, but suspect some moderate condition causing tissue deterioration, over time, such as osteoarthritis for example.
Hope this helps and I wish you the best get this resolved.