A disc implant is provided which maintains intervertebral spacing and
stability of the spine. In an embodiment, a disc implant may include four
or more components. Components of the disc implant may include engaging
plates and two or more members positioned between the engaging plates. In
certain embodiments, a disc implant may include a retainer positioned
between one of the engaging plates and one of the members. Complementary
portions of the implant components may allow for lateral movement,
anteroposterior movement, and/or axial rotation of the engaging members
relative to each other during use. In some embodiments, at least one of
the members may include a stop to inhibit movement of adjacent vertebrae
outside of normal physiological ranges.