The Clinical Results after Posterior Ligaments Preserving Fenestration in Lumbar Spinal Stenosis: The Port-Hole Decompression

Abstract

Purpose: To describe the technical skills and to estimate the clinical outcomes of port-hole decompression preserving the posterior ligaments during lumbar spinal stenosis surgery. Materials and Methods: Between March 2014 and March 2016, a total of 101 patients who underwent port-hole decompression were retrospectively analyzed. The mean age was 71.3 years (58-84 years) and there were 46 males and 55 females. The mean follow-up period was 18 months. Degenerative spondylolisthesis was observed in 24.8% of patients (25/101). Port-hole decompression was performed by removing the central portion of the distal part of the upper lamina with a burr. Then, the contralateral side of ligamentum flavum and hypertrophied facet joints were removed. We estimated the lumbar lordotic angle using radiographs, and measured the depth from skin to upper lamina central area using magnetic resonance imaging axial images. We estimated the mean slip angle and mean degree of slip in preoperative and postoperative radiography in standing flexion and extension. We also measured the operational time, length of skin incision, and blood loss. The clinical results were estimated by a walking distance caused by neurologic intermittent claudication, visual analogue scale, and Oswestry disability index. Results: Most patients were generally older, and the mean lordotic angle was 25.3°, which is considered to be lower when compared with younger people. The mean depth from skin to lamina was mean 5.4 cm. With respect to the radiological results, there were no significant differences between the preoperative and postoperative groups. The operation time, length of skin incision, and bleeding were not increased proportionally to the operation level. The walking distance caused by neurologic intermittent claudication, visual analogue scale, and Oswestry disability index of the post-operative group were all improved compared with the pre-operative group. Conclusion: The port-hole decompression, which decompresses the contralateral side while preserving the posterior ligaments and facet joints may be a useful technique for elderly patients with multiple level stenosis, minimizing spinal segmental instability.