We have developed VTK classes for NURBS surface visualization and interactive editing for 3D Slicer. We released everything with a non-restrictive license, so you can copy-paste these everything into your project but if you are working in the medical domain probably you are better off using them in Slicer.
It supports both NURBS and Bezier surfaces, plane or tube topology, quad or triangle mesh output, visualization and interactive editing in 3D and slice views.
You can give it a try by installing 3D Slicer and then open the extensions manager in the application and install the SurfaceMarkup extension (takes just a few clicks). The new “Grid surface” markup type will show up in the “Markups” module.
We have modules for surface fitting, lofting, etc. that we’ll release as soon as corresponding papers are published.