A selectively expanding spine cage has a minimized
diameter in its unexpanded state that is smaller than the
diameter of the neuroforamen through which it passes in the distracted spine. The cage conformably engages between the endplates of the adjacent vertebrae to effectively distract the anterior
disc space, stabilize the motion segments and eliminate
pathologic spine motion. Angular deformities can be corrected, and natural curvatures restored and maintained. The cage enhances spinal arthrodesis by creating a
rigid spine segment, or if filled with compressible substances, the cage can be used for
motion preservation between vertebral bodies. Expanding selectively (anteriorly, along the
vertical axis of the spine) rather than uniformly, the cage height increases and holds the vertebrae with fixation forces greater than adjacent bone and
soft tissue failure forces in natural
lordosis. Stability is thus achieved immediately, enabling patient function by eliminating painful motion. The cage shape intends to rest
proximate to the anterior column cortices securing the desired spread and fixation, allowing for bone graft in, around, and through the
implant for arthrodesis whereas for
arthroplasty it fixes to endpoints but cushions the spine naturally.