Method of making a prosthetic intervertebral disc joint assembly

A prosthetic intervertebral disc joint assembly for replacing at least a portion of an intervertebral disc between first and second adjacent vertebrae, each vertebra having an anterior side and a posterior side, the assembly having a leading end which leads as the assembly is inserted into the intervertebral space and a trailing end opposite the leading end, and an intervertebral plane passing therebetween which substantially aligns with the intervertebral plane between the adjacent vertebrae when installed, the assembly comprising:

• a first component for engaging a first vertebra, the first component having an intervertebral portion insertable between adjacent vertebrae and having a bone-engaging side for engaging an endplate of the first vertebra and an inner side opposite the bone-engaging side, the intervertebral portion of the first component further having a leading end and a trailing end, the inner side of the intervertebral portion of the first component having an articulating surface comprising a generally convex surface;
• a second component for engaging a second vertebra, the second component having an intervertebral portion insertable between adjacent vertebrae and having a bone-engaging side for engaging an endplate of the second vertebra and an inner side opposite the bone-engaging side, the intervertebral portion of the second component further having a leading end and a trailing end, the inner side of the intervertebral portion of the second component having an articulating surface comprising a generally concave surface;
• wherein the convex articulating surface of the first component is sized and shaped to pivot in the concave articulating surface of the second component, and
• wherein the first component further comprises a fixation portion for securing the first component to the anterior side of the first vertebra, said fixation portion extending from the trailing end of the intervertebral portion of the first component and wherein the second component further comprises a fixation portion for securing the second component to the anterior side of the second vertebra, said fixation portion extending from the trailing end of the intervertebral portion of the second component,
• wherein the generally convex articulating surface of the first component is substantially spherically curved and the generally concave articulating surface of the second component is correspondingly substantially spherically curved to match the radius of curvature of the articulating surface of the first component,
• and wherein the fixation portion of the first component has a proximal portion proximal to the intervertebral portion of the first component, the proximal portion of the first component having an outer side at least part of which presents towards the second component when the assembly is implanted, at least part of the outer side of the proximal portion of the first component being aligned with or substantially within a notional arc, the perimeter of which aligns with the convex articulating surface of the first component in the sagittal plane, such that said at least part of the proximal portion of the first component does not impinge against the second component during flexion of the intervertebral disc joint assembly in use.