This paper presents the application of finite element method in an artificial disc modelling. The prosthesis consisted of two metal plates and a flexible elastomeric core made of the nanocomposite polyurethane. Two types of connections between the plates and the core were compared: the device with an integral inlay and the device with a separate inlay coming into contact with the plates. The artificial disc with a separate inlay imitated better the human intervertebral disc. The main target of this paper was to evaluate the characteristics of force-displacement and moment-angle for the new design of the prosthesis with a separate inlay under compression, sagittal bending, shear and axial rotation. For some analyzed cases except the axial rotation and shear, where the prosthesis was too flexible, the results were roughly similar to those observed in the human spinal segment. The material effort in the prosthesis under compressive load was comparable in both types of connections between the plates and the core.