An implantable prosthesis component for a joint prosthesis includes a flexible wall, a proximal side comprising a rigid portion for connecting to a first bone at a joint and a distal side comprising a rigid portion for connecting to a second bone at the joint. The flexible wall has an inverted spherical shape and defines an inner cavity of the implantable prosthesis component. The inner cavity is filled with a fluid. The flexible wall is deformable such that relative movement between the first and second bone causes deformation of the implantable prosthesis component.
