Recovery from knee arthroscopy

I had knee arthroscopy 6 weeks ago to smooth the cartilage on the back of the patella, remove scar tissue, and correct a structural defect in a groove at the bottom of the femur that helps the kneecap track properly (needed to widen it).  I had a lot of swelling over the first 4 weeks.  This has finally subsided for the most part but I am struggling to get the full flexion back.  I am still only at 105 degrees despite physio, biking, and the elliptical trainer.  The tightness above the knee and in the lower part of the joint continues to persist.

How long should it take to recover from a knee arthroscopy like this?  Should I be concerned about the slow progress and what can I do to get myself back on track to full recovery as quickly as possible?

Thanks for your help in advance.