Pengembangan sistem penilaian baru untuk menentukan adanya ketidakstabilan dan kebutuhan fusi pada Stenosis Spinal Lumbar Degeneratif - Indonesia Score of Spinal Instability (ISSI) = Development of a new assessment system to determine the presence of instability and the need for fusion in Degenerative Lumbar Spinal Stenosis - Indonesia Score of Spinal Instability (ISSI)