INTRODUCTION

Adjacent segment disease (ASD) is a well-recognized sequela after pedicle screw assisted posterior lumbar fusion (PLF). Incidence of ASD greatly varies in published studies.

RESEARCH QUESTION

To determine the long-term risk of ASD and subsequent reoperations in three different diagnosis groups.

MATERIALS AND METHODS

We searched for patients who underwent a primary PLF in our hospital between 1992 and 2012 due to degenerative disc disease without spondylolisthesis (DDD), spondylolysis with spondylolisthesis (SL) and degenerative spondylolisthesis (DS). We excluded fusions above L3, fusions of more than two segments, surgical complications, ASD below the PLF, scoliosis, trauma, tumor and primary infections. Follow-up was terminated at reoperation for ASD, otherwise it was continued until February 2023. Kaplan-Meier survival analysis was performed to assess the reoperation-free survival. Cox regression analysis was performed to test the causal relationship between ASD and independent variables.

RESULTS

481 patients were included in the analysis. Among them, 138 had surgery due to DDD, 214 due to SL and 129 due to DS. The mean follow-up time was 15 years. In total, 147 (30.6 %) developed a symptomatic ASD and 97 (20.2 %) were reoperated due to it. Mean time to reoperation was 12.1 years in DDD, 11.1 years in SL and 11.2 years in DS. According to COX regression analysis, DS and DDD were independent predictors for reoperation due to ASD over SL.

CONCLUSIONS

The risk for ASD and subsequent reoperation was higher than in previously published studies. DS seemed to be the strongest predictor for reoperation due to ASD.