Abstract: An intervertebral spacer is to be inserted between two vertebral bodies. The intervertebral spacer including a pair of block bodies. Each of the block bodies has an abdominal side portion to be directed to an abdominal side of a patient when inserted in the vertebral bodies and a back side portion to be directed to a back side of the patient when inserted in the vertebral bodies. Each block body is configured such that a width of the abdominal side portion is greater than a width of the back side portion.