Intervertebral devices

An intervertebral fusion device, comprising:

• a superior component 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;
• an inferior component 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;
• a core component configured for insertion between the superior and inferior components whereby a separation between the superior and inferior components is determined, the core component having first and second lateral sides which each face in a transverse direction which is orthogonal to a direction of insertion of the core component and to a direction of separation of the inferior and superior components, the first and second lateral sides facing in opposite directions;
• a first retention mechanism comprising a first finger and a first recess;
• and
• a second retention mechanism comprising a second finger and a second recess,
• wherein a proximal end of each of the first and second fingers is attached to the superior or inferior components at an anterior edge of the inferior or superior component that first receives the core component when the core component is inserted between the superior and inferior components whereby the finger is unitary with the superior or inferior component, and the finger is unsupported and unattached along its length except at its proximal end whereby the finger flexes along its length relative to the inferior or superior component,
• wherein the proximal end of the first finger is attached at a first lateral side of the inferior or superior component and the first finger extends in the direction of insertion towards a posterior edge of the inferior or superior component, and the proximal end of the second finger is attached at a second lateral side of the inferior or superior component and the second finger extends in the direction of insertion towards a posterior edge of the inferior or superior component whereby the first and second fingers are spaced apart from each other in the transverse direction,
• wherein the first finger defines a first protrusion at a distal end thereof and the second finger defines a second protrusion at a distal end thereof, the first and second protrusions spaced apart from and facing each other in the transverse direction,
• wherein the first and second recesses are defined respectively on the first and second lateral sides of the core component, and
• wherein the first and second lateral sides of the core component are received between the first and second fingers during a first stage of insertion of the core component to thereby guide the core component, a posterior end of the core component bearing against the first and second protrusions at the end of the first stage of insertion to flex the first and second fingers apart in the transverse direction, and during a second stage of insertion following the first stage of insertion the first and second protrusions are received in the first and second recesses respectively under spring bias exerted by the first and second fingers to thereby present resistance to ejection of the core component from between the superior and inferior components.