Patent ID: 8337531

Claim:
A method of supporting and distracting opposing vertebral bodies of a spine in a space therebetween, comprising the steps of: inserting into said space between said vertebral bodies in a direction of introduction an expandable device including a top element having an upper contact surface, an opposite bottom element having a lower contact surface and an expandable intermediate structure therebetween, said upper contact surface engaging the lower surface of an upper vertebral body and said lower contact surface engaging the upper surface of a lower vertebral body, said device having a maximum unexpanded height that is defined by the distance between said upper contact surface and said lower contact surface when said device is in an unexpanded condition, said expandable intermediate structure capable during expansion of moving said upper contact surface and said lower contact surface apart in an expansion direction along the axis of said spine while maintaining said upper contact surface and said lower contact surface in a substantially fixed position relative to each other in the direction of introduction, said expandable intermediate structure comprising an intermediate element movable between said top element and said bottom element in said direction of introduction that is generally normal to the direction of the device expansion, said intermediate element including a lifting surface engaging a cooperative engagement surface on one of said top element and said bottom element during movement of said intermediate element and a cooperative constraint between said intermediate element and one of said top element and said bottom element configured to limit relative movement therebetween in the direction of introduction upon completion of expansion; expanding said expandable device within said space by moving said intermediate element to move said top element and said bottom element to thereby distract and support said vertebral bodies along the axis of said spine, said device defining an expanded height between said upper contact surface and said lower contact surface when said device is in an expanded condition; and ending said expansion when said expanded height is at least 1.5 times the unexpanded height.