In reply to Wee Davie:
I can confirm that falling off a road bike can fracture your femur, my mate Chilton did exactly that with his first THR and had to spend 5 days in hospital waiting for the new bits to be fitted- long stem and lots of cable ties holding the bone bits together. He still cycles, has done a hundred miler, but does not run at all.
My biking is all on-road, my attempts to mountain bike scared me as a fall is much more likely. I run on the roads and towpaths and in the hills - downhill, anyway. Indoor bouldering is V4 max on a good day, I have fallen from the top of the wall several times and so far landed ok but there is a bit of a risk in a twisting fall. Outdoors, I have managed E1 on grit a couple of times, age is my restriction rather than hips...
Dislocation is very rare with larger-ball devices, once the soft bits have regained their strength. Are you sure a Birmingham hip is not possible, or is your surgeon one of those who does not do them or believe in them? It makes for a better mechanical repair but does require decent bone and a femoral head that has not become necrotic. And a THR revision later is an easy option...