Chris Quan
Ansys Employee

In Static Structural system, force is static. In Explicit Dynamic system, force is dynamic (impact) and thus will cause higher stress and larger deformation than the same force applied in Static Structural system.

How did you apply the force? Was it a step load? If yes, can you ramp up the force with time from 0 to its full magnitude in the force BC?

What is the material model used for the bones? Does the same material model works with both Static Structural & Explicit Dynamics systems? 

If you found that two bodies were not bonded together at their interface, you can increast its Offset in the bonded contact to make them bonded. Then you can use user-defined results Bond_Status to verify if they are bonded (Bond_Status > 0).