Objective To compare the effectiveness and radiological changes of posterior decompression combined with Coflex interspinous dynamic reconstruction or lumbar 360° fusion for degenerative lumbar spinal disorders at L4, 5. MethodsBetween October 2008 and November 2010, a comparative study was carried out on patients with degenerative lumbar spinal disorders at L4, 5. In group A, 29 patients underwent posterior decompression combined with Coflex interspinous dynamic reconstruction; there were 20 males and 9 females with an average age of 45.1 years (range, 21-67 years); and the disease duration was 2 months to 4 years. In group B, 31 patients underwent posterior decompression combined with lumbar 360° fusion treatment; there were 16 males and 15 females with an average age of 56.2 years (range, 32-86 years); and the disease duration was 3 months to 6 years. Except the age, there was no significant difference in gender, disease duration, and etiology etc. between 2 groups (P gt; 0.05). The results were assessed by Japanese Orthopaedic Association (JOA), visual analogue scale (VAS) scores, and Oswestry disabil ity index (ODI). The range of motion (ROM) and intervertebral height of affected and adjacent segments, and the ROM of lumbar were measured before operation and last follow-up. Results Significant differences were found in the operative time and blood loss between 2 groups (P lt; 0.05). Intraoperative dural tear occurred in 1 case of group B, spinal canal venous plexus hemorrhage in 1 case of group B, and postoperative cerebrospinal fluid leakage in 2 cases of group A and B respectively, showing no significant difference (χ2=0.119, P =0.731). The follow-up was 12-21 months in group A and was 12-23 months in group B. At the last follow-up, the JOA, VAS scores, and ODI of groups A and B were significantly improvedwhen compared with the preoperative values (P lt; 0.05). The VAS score of group A was significantly higher than that of group B (P lt; 0.05). There was no significant difference in the intervertebral height of L4, 5 and L5, S1 of groups A and B between pre- and post-operation (P gt; 0.05). In group B, the intervertebral height of L3, 4 was significantly reduced (P lt; 0.05) compared with the preoperative one. There was no significant difference in the ROM of L5, S1 and ROM of lumbar in groups A and B between preand post-operation (P gt; 0.05). At last follow-up, the ROM of L4, 5 was significantly reduced in group A (P lt; 0.05), and the ROM of L3, 4 was significantly increased in group B (P lt; 0.05). Except significant differences in the intervertebral height and ROM of L3, 4 between 2 groups (P lt; 0.05), no significant difference was found in other parameters (P gt; 0.05). Conclusion Posterior decompression combined with Coflex interspinous dynamic reconstruction has the same effectiveness as lumbar 360° fusion in treating degenerative lumbar spinal disorders at L4, 5, but the former has a protective effect on the adjacent segments of fusion and is recommended for initial treatment of young adults and the elderly and frail patients with recurrent.