How can I make this active contour more robust?

Hi

I attach the segmented images. As you can see the contour is not robust enough. As a result, there are gaps between the head of the tip of the spike and the rest of the body. The contour breaks and diferent pieces are created.

I don't want this. I want seamless contour with no gaps.

I also attach the code I use.

Any help appreciated.

Thank you.

Regards

Stelios Fanourakis