So after 4 days of non-running my knee is feeling much better. There is some slight stiffness to it when I wake up, overall I think there's a slight patellar tendonitis. Naturally I've done over 6km of walking each day just to and from work but no other exercise. I'm going swimming soon and hopefully that won't upset it.
The big thing to consider now is when to try a run and how much can I risk? The 40km per week really seems to be a threshold for me. Over 2014 I've ramped up to it twice and each time had to back off. This time I have been more gradual and included a rest week after 2 weeks of effort. I'm disappointed that this scheme hasn't worked out. Maybe this is just a little set back as my knee is not as delicate as it was in spring - I really don't want to over do it and go back that far again.
Being self-critical I know that I have neglected the leg strengthening exercises at home. At the circuit class I have been doing more squats and lunges and managing to get them a little deeper without invoking pain.
Looking online there is a lot if excitement around declined single leg eccentric squats, some articles suggest they are great (note there was 6 week's rest in this study!), others warn off. The whole business of eccentric loading is very unclear from serious literature. One of the physiotherapists I saw last year was keen on eccentric single leg squats without the decline board but then again he encouraged too much loading!
Platelet-rich therapy is up and coming and some authors claim great success. Indeed they may genuinely be successful as many innovative techniques are incredibly sensitive to operator's skill and methodological 'tricks' (indeed I went to Scandinavia to do post-doctoral research specifically to see certain techniques in the hands of experts). Unfortunately it seems that PRT does not offer a reproducible gain.
I am thinking that long term slow loading is the way to go; slower but fewer risks?