Intervertebral devices

A method of installing an intervertebral fusion device in an intervertebral space between first and second vertebrae, the intervertebral fusion device comprising a superior endplate, an inferior endplate, a core component and a retention mechanism comprised in the core component, the retention mechanism comprising first and second retention mechanism portions which are movable relative to each other between a contracted condition and an expanded condition, the method comprising:

• positioning the superior and inferior endplates relative to each other such that a bottom side of the superior endplate and a top side of the inferior endplate oppose each other;
• inserting the core component between the superior and inferior endplates whereby a separation between the superior and inferior endplates is determined;
• and
• disposing the intervertebral fusion device in the intervertebral space, wherein:
• the first and second retention mechanism portions are closer together in the contracted condition whereby the first and second retention mechanism portions do not protrude beyond a periphery of the core component at its upper and lower sides respectively, the core component insertable between the superior and inferior endplates when in the contracted condition, and
• the first and second retention mechanism portions are further apart in the expanded condition whereby the first and second retention mechanism portions protrude beyond the periphery of the core component at its upper and lower sides respectively, the first and second retention mechanism portions interengaging respectively with the superior and inferior endplates when in the expanded condition and when the core component is received between the superior and inferior endplates to thereby present resistance to movement of the core component from between the superior and inferior endplates.