Usual reason for Sprouts 'blowing' like this is that the plants were not planted firmly enough. My old gardening guru said "Plant 'em wi' an 'ammer" Or the strong winds we have had have rocked the plants loosening the roots.
All is not lost, you can still eat them. Treat them like small cabbages, they taste just the same. We often stir fry ones like this.

Thanks Owdboggy, I'll try your suggestion. Not all the plants have 'blown' so we won't starve yet.