69 patients scheduled for single-level posterior lumbar interbody fusion were randomized to one of two different implant groups: one group received an autologous cage consisting of the resected spinous process and lamina (ACSP) from earlier in the procedure, and one group received a polyetheretherketone (PEEK) cage. The purpose of this study was to determine and compare clinical and radiographical results of the ACSP group in comparison to the PEEK cage group over 24-month follow-up. Results demonstrated no significant differences between groups in either visual analog pain scores, functional status, fusion success, restoration of disc height, or regional lordosis of the operative level.