Treatment outcomes of microscopic decompression laminotomy with tubular retractors for degenerative lumbar spinal stenosis - Assessing the patient at the time of hospital discharge, microscopic decompression laminotomy showed rapid improvement of clinical symptoms immediately after surgery with statistically significant difference of p <0.001, lumbar back pain went from 5.03 ± 1.24 to 1.97 ± 0.85 based on VAS; Nerve root pain decreased from 7.23 ± 0.98 to 2.71 ± 1.03 according to VAS; JOA before surgery 11.29 ± 1.35, after surgery 23.23 ± 2.75; ODI before surgery 66.32 ± 5.39% after surgery 29.21 ± 6.71%.