Personally, I think this is ridiculous and am searching for an alternate travel insurance provider who is a bit more enlightened. We bandits, after all, are loads more healthy post-surgery than we were before. The surgery was the solution, not the problem, and certainly shouldn't be regarded as a 'condition'! In theory, they should reduce our premium because of the band because we are less at risk of diabetes, heart attacks and strokes, to say nothing of all sorts of mobility problems.
I wonder whether we should have declared it at all? I guess I wouldn't be that averse to paying a slightly higher premium, but for the company to simply exclude this 'condition' and not cover it is just silly and money-grabbing.
Anyway, I will investigate further and see what I find out. Meanwhile, I advise you NOT to purchase HSBC travel insurance!