It turns out that the joint where my big toe joins on to my foot doesn't really have any cartilage left in it. The bones around the joint have a number of bony growths and spikes on them as a result of the damage the lack of cartilage has caused, and the joint movement is limited to about 10 degrees of flex rather than the more normal 90. Plus it hurts, quite alot, all of the time. Advanced osteoarthritis of the big toe joint, just what a 37 year old with an interest in ultrarunning wants to be diagnosed with.
The doctor explained the three options to me as:
1. A cheliectomy (not sure of the spelling), which means cutting open the joint and cutting of the bits of bone that are inhibiting the flex, thereby freeing the joint up but unfortunately since there is no cartilage left it probably won't reduce the pain that much, and the offending bony bits will grow back over time.
2. Fusing the joint, so it won't flex at all and running would be a bit difficult. This should stop the pain, but also has the drawback that I would not be able to wear high heels again.
3. Replacing the joint - apparently this option is only suitable for couch potatoes (the doctor's words, not mine) and a runner would wear the new joint out in a year. Plus, it would seem to me that to replace the joint in question about a quarter of your foot would have to be cut out, and I don't think I fancy that.
I guess the fourth option, and the one I'm settling for for the timebeing, is to put up with the pain and get on with it. I've had a sore foot for about seven years now and though it is steadily getting worse it's manageable at the moment. My running gait has definitely changed over the past few years (as evidenced by a bunch of compensation injuries and a different wear pattern on my shoes) in order to protect the damaged bit of my foot, and it feels more natural this year than it has done previously. The doctor recommended running in stiff soled shoes (those with a rockplate in are ideal), which I have been doing since Christmas and which I think helps, though strangely when I run with no shoes on there is virtually no pain at all. So I think running is okay, but I probably need to accept that my moonwalking days are over.
That said, the pain in my foot is generally worse this year than last year, and I've had a couple of episodes when I could hardly walk for a week, never mind run. I'll be in Milngavie next Saturday to have a go at the Fling, but I think realistically only after seeing how the joint copes with 52 miles of trail will I decide whether I will be back in Milngavie very early one Saturday morning in June. I've got my fingers crossed that I will be, and would cross my toes as well if I was able to.