An intervertebral fusion device (10, 110, 210) comprising: a superior component (70, 170, 270) having a superior component top side and a superior component bottom side, the superior component being configured to be received in an intervertebral space between first and second vertebrae whereby the superior component top side abuts against the first vertebra, the superior component comprising first and second superior parts (72, 74) which are coupled to each other to allow the first and second superior parts to move apart to thereby increase a perimeter of the superior component top side; an inferior component (40, 140, 240) having an inferior component top side and an inferior component bottom side, the inferior component being configured to be received in the intervertebral space between the first and second vertebrae whereby the inferior component bottom side abuts against the second vertebra, the superior component bottom side and the inferior component top side opposing each other when the superior and inferior components are received in the intervertebral space, the inferior component comprising first and second inferior parts (50, 52, 150, 152, 250, 252) which are coupled to each other to allow the first and second inferior parts to move apart to thereby increase a perimeter of the inferior component bottom side; and a core component (20, 120, 220) configured for insertion between the superior and inferior components whereby separation between the superior and inferior components is determined, the core component inter-engaging with each of the superior and inferior components upon insertion, wherein the superior and inferior components are unattached to each other before the core component is inserted between the superior and inferior components, and wherein, as the core component (20, 120, 220) is progressively inserted between the superior (70, 170, 270) and inferior (40, 140, 240) components, the core component: bears against the first and second superior parts (72, 74) to push the first and second superior parts progressively apart; and bears against the first and second inferior parts (50, 52, 150, 152, 250, 252) to push the first and second inferior parts progressively apart, and wherein, the core component (20, 120, 220) is integrally formed. a superior component (70, 170, 270) having a superior component top side and a superior component bottom side, the superior component being configured to be received in an intervertebral space between first and second vertebrae whereby the superior component top side abuts against the first vertebra, the superior component comprising first and second superior parts (72, 74) which are coupled to each other to allow the first and second superior parts to move apart to thereby increase a perimeter of the superior component top side; an inferior component (40, 140, 240) having an inferior component top side and an inferior component bottom side, the inferior component being configured to be received in the intervertebral space between the first and second vertebrae whereby the inferior component bottom side abuts against the second vertebra, the superior component bottom side and the inferior component top side opposing each other when the superior and inferior components are received in the intervertebral space, the inferior component comprising first and second inferior parts (50, 52, 150, 152, 250, 252) which are coupled to each other to allow the first and second inferior parts to move apart to thereby increase a perimeter of the inferior component bottom side; and a core component (20, 120, 220) configured for insertion between the superior and inferior components whereby separation between the superior and inferior components is determined, the core component inter-engaging with each of the superior and inferior components upon insertion, wherein the superior and inferior components are unattached to each other before the core component is inserted between the superior and inferior components, and wherein, as the core component (20, 120, 220) is progressively inserted between the superior (70, 170, 270) and inferior (40, 140, 240) components, the core component: bears against the first and second superior parts (72, 74) to push the first and second superior parts progressively apart; and bears against the first and second inferior parts (50, 52, 150, 152, 250, 252) to push the first and second inferior parts progressively apart, and wherein, the core component (20, 120, 220) is integrally formed.