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Analysis of Risk Factors for Early Adjacent Segment Disease Underwent Revision Surgery within 5 Years after Lumbar Spinal Fusion

Introduction There are many concerns about adjacent segment disease after lumbar spinal fusion using pedicle screws. Of them, we have a question which occurs early adjacent segment disease(EASD) within 5 years. We analyze the risk factors about EASD in patients who underwent revision surgery within 5 years from first operation. Materials and Methods From August 1988 to December 2007, 657 patients underwent lumbar spinal fusion of 3 and less segment to treat degenerative lumbar disease. Among them, 137 patients underwent revision surgery within 5 years due to adjacent segment disease or previously followed more than 5 years were included in this study. Gender, age, fusion method, preoperative diagnosis, number of fusion segments and radiological measurements were analyzed. In radiological measurement, pre-& post-operative lumbar lordotic angle(LLA), pre-& post-operative fusion segment lordotic angle(FSLA), pre-& post-operative FSLA per level, correction of LLA, correction of FSLA, and correction of FSLA per level were estimated. Statistical univariate analysis was performed with the Chi-square test and multivariate logistic regression analysis was done by using SPSS 14.0. Results There were 13 patients with revision surgery due to EASD. 6 patients were operated by decompression or discectomy and 7 patients needed additional fusion. In univatiate analysis, there was little relationship between EASD and gender, age, preoperative diagnosis, number of fusion segments, pre-& post-operative LLA, pre-& post-operative FSLA, pre-& post-operative FSLA per level, correction of FSLA and correction of FSLA per level. However, the frequency of EASD was significantly high in cases where PLIF was more than PLF(p = 0.023), correction of LLA was > 15°(p = 0.021) and correction of FSLA per level was > 5°(p = 0.049). In multivariate logistic regression analysis, the frequency of ESAD was significantly high in case where PLIF was more than PLF(odd ratio = 17.866) and correction of LLA was > 15°(odd ratio = 19.282). Conclusions There was no statistical significance between EASD and gender, age, preoperative diagnosis, number of fusion segments, pre-& post-operative LLA, pre-& post-operative FSLA, pre-& post-operative FSLA per level, correction of FSLA and correction of FSLA per level. However, PLIF and correction of LLA more than 15 degree increased risk of EASD.