A prosthetic intervertebral spacer includes a body having a front end, a rear end, an anterior side, a posterior side, a top surface, and a bottom surface, and an arcuate interface extending away from the body and being connected to the rear end and the posterior side of the body. A method of inserting and positioning the spacer includes engaging a tool to the interface, inserting the spacer at least partially into the intervertebral disc space by moving the tool along an insertion direction, and allowing the spacer to rotate with respect to the insertion direction within the intervertebral disc space while continuing to move the tool along the insertion direction.