Objective: In our study, we aimed to research the changes of adjacent segment degeneration in posterior lumbar spinal fusion patients.

Material and Method: In this study, lumbar spondylolysthesis operation applied 36 patients were investigated. Posterior stahilisation and fusion were applied to the first group of 26 patients hy using transpedicular screw and to the second group of 10 patients hy using interbody cage. Patients' JOA scales, adjacents segment disc heihts, osteophyte formations, lomher lordosis angles, and lysthesis degrees were evaluated before and after operation.

Results: In hoth groups, as bej'ore and and after operation, the clinical healing was detected statistically significant according to JOA scale measurement. Postoperative lomher lordosis angles were increased, upper and lower disc spaces heights nex to the fused segments were decreased, new instability nex to the segment has not heen found and thus these results were not statistically significant.

Conclusion: We observed significant clinical improvement in posterior lumhar spinal fusion applied patients in early postoperative period and urısignificant degeneration in adjacent segments.