Excellent, thank you.
Prior to the onset of pain, following my slip, I would walk 10/15k steps per day - most being on my morning walk. I thoroughly enjoyed the exercise and fresh air. Despite being overweight (95kg-115kg) the walking never caused any obvious issues with the knee. Now there are days when I cannot walk up and down for a game of bowls. I accept that I haven't got the balance of medication right but I really don't want tone on NSAIDs longer than necessary.
I have probably been a bit blinkered to walking, as my main exercise, when this is clearly unviable. I perhaps need to look at exercising the knee in the condo swimming pool and finding the way to the gym to use the static exercise bike.
It seems logical to pursue the MRI route so that I can be confident - first - with the professional diagnosis, and then look at the best way of treating the results.