The present invention relates to an intervertebral fusion device (10) comprising a superior component (20), an inferior component (40) receivable in an intervertebral space between first and second vertebrae, with the core component (80) insertable between the superior and inferior components to determine a separation between the superior and inferior components. The superior, inferior components and core components comprise respective formations and profiles. The formations (54, 68) present a barrier to separation of the core from one of the inferior and superior components during insertion of the core component. The profiles guide the core component during insertion of the core component while presenting no barrier to separation from each other during its insertion. The components comprise further formations (39, 76) which present a barrier to separation of the components from each other once the core has been fully inserted between the inferior and superior components.