Posterio spinal device and method

A method of treating a patient having upper and lower vertebrae and an intervertebral space between the upper and lower vertebrae, the method comprising:

• providing an implantable assembly comprising a first segment, a second segment and a third segment, the first segment pivotally connected to the second segment with a first pivot joint, the second segment connected to the third segment with a second pivot joint;
• introducing the first segment into intervertebral space when the first segment, the second segment and the third segment are arranged in an elongate configuration;
• pivoting the first segment about the first pivot joint when the first segment is introduced into the intervertebral space;
• and
• pivoting the third segment about the second pivot joint when the third segment is introduced into the intervertebral space, such that each of the first, second, and third segments is not parallel with each of the other segments so as to form a non-parallel arrangement, wherein the first, second, and third segments form the three sides of a triangle so that the non-parallel arrangement is a triangular arrangement, and such that the implantable assembly supports the upper and lower vertebrae when placed in the intervertebral space.