The Potential Role of the Posterior Elements in Lumbar Spine Laminoplasty to Protect the Intervertebral Disc and Improve Walking Ability—Retrospective Comparative Study

<b>Objectives</b>: To investigate whether preservation of the posterior elements protects the spine from degeneration and improves postoperative symptoms in lumbar spine laminoplasty. <b>Methods</b>: Eighty-five consecutive patients who underwent lumbar spine laminoplasty were retrospectively reviewed. They were non-randomly stratified into two groups, the posterior elements resection (R) group and the preservation (P) group, and they were followed for two years after surgery. We radiographically analyzed the conditions of the spine and intervertebral disc (IVD) two years after surgery. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) was used for symptom assessments. Logistic regression analysis was performed to determine whether the kissing spine was a significant factor for the outcomes in group R. <b>Results</b>: The 2-year D score increment and 2-year IVD height decrement was lower in group P. No difference was found in the flexion-extension angles or incidence of instability between groups. The JOABPEQ revealed higher scores in walking ability, social life function, and mental health in group P one year after surgery. Walking ability was the only score that remained higher two years after surgery. The visual analog scale of pain in the buttocks and lower limbs was lower in group P only one year after surgery. Finally, the kissing spine was not a significant factor in any outcome. <b>Conclusions</b>: The preserved posterior elements were considered to protect the IVD in lumbar spine laminoplasty. In addition, they positively affected postoperative health status from multiple aspects.