An intervertebral spacer is designed particularly for patients who are not candidates for total disc replacement. The spacer maintains disc height and prevents subsidence with a large vertebral body contacting surface area while substantially reducing recovery time by eliminating the need for bridging bone. The intervertebral spacer or fusion spacer includes a rigid spacer body sized and shaped to fit within an intervertebral space between two vertebral bodies. In one embodiment, the spacer body has two opposed metallic vertebral contacting surfaces, at least one fin extending from each of the vertebral contacting surfaces and configured to be positioned within slots cut into the two vertebral bodies. Holes, if present, cover less than 40 percent of the entire vertebral body contacting surfaces to provide increased bone ongrowth surfaces and to prevent subsidence.
