I would call the medical school and ask...I bet it will come down to them wanting you to have the degree finished prior to matriculating. But, at the same time, they may be willing to work with you. For instance, at one school I interviewed at, several years ago, they told me and another PhD student that if we were accepted, they would be willing to work with us since graduate programs can be somewhat unpredictable. So, you might be able to convince them that you'r obligation to the school will be next to nill if you can show them you defended your thesis and what not prior to matriculating and that you just have to wait for the graduate school to say the margins on your thesis are okay and what not.