What are the features (i.e.) commands I need to use to model a bone shape in SolidWorks or in CATIA?
Spline-made variable-shaped rings on perhaps numerous planes, and a lot of lofting layers in multiple directions/axis... This is such an organic model that you are going to have a lot of work to do or, get a scan or an x-ray.
If you get an x-ray, you can use the trace feature of an inserted picture to build your splines on that.
Best of luck,