An interbody spacer is disclosed and includes a body portion defining a longitudinal axis. The longitudinal axis includes a distal end portion, a proximal end portion, opposed side surfaces that extend between the distal and proximal end portions, and top and bottom surfaces configured and adapted to engage vertebral bodies. The body portion includes a cavity defined through the top and bottom surfaces that increases in width at a medial position thereof. The cavity is configured to retain biological material therein. A method of performing spinal surgery is also disclosed.