RESUMO
PURPOSE: The purpose of this study is to analyze the risk factors for early adjacent segment disease (EASD) in patients undergoing revision surgery within 5 years from the first operation as compared with those after more than 10 years. MATERIALS AND METHODS: A total of 755 patients with degenerative lumbar disease underwent lumbar spinal fusion of 3 or less segments between August, 1988 and May, 2009. Of these, 44 patients underwent revision surgery due to adjacent segment disease (ASD) until May, 2014. These patients presented with ASD, 19 and 13 of whom underwent revision surgery within 5 years and after more than 10 years of the first one, and were thus assigned to group A (n=19) and group B (n=13), respectively. Thirty-two of these patients were enrolled in this study and baseline and clinical characteristics, including sex, age, fusion method, preoperative diagnosis, the number of fused segments, fusion level, and radiological measurements were compared between the two groups. Radiological measurements included pre- and postoperative lumbar lordotic angle (LLA), pre- and postoperative fusion segment lordotic angle (FSLA), pre- and postoperative FSLA per level and the correction of LLA, FSLA, and FSLA per level. For statistical analysis, univariate analysis with the chi-square test was performed using SPSS 14.0. RESULTS: In group A, the number of patients undergoing posterior lumbar interbody fusion (PLIF) rather than posterolateral fusion, those with postoperative FSLA per level of <20° and the adjacent segment levels to L4-5 and L5-S1 was significantly larger compared with group B (p=0.018, 0.046, and 0.009, respectively. CONCLUSION: In conclusion, our results indicate that the degree of risk of EASD was relatively higher in association with PLIF, postoperative FSLA per level of <20° and the adjacent segment levels to L4-5 and L5-S1.