Chances are there's too much fat in the meat and that's why they are not sticking together. It could also be that it is too fine of a grind, a coarser grind for the meat usually results in it sticking a bit better. You could try adding breadcrumbs or flour along with some egg or egg white and see if that works.

It may also help if you start off with them cold before you start cooking them, it will give them a chance to form a crust before they start cooking.