Sagittal spinal imbalance may be caused by orthopedic problems, compression of the neural structures of the spinal canal, and pain syndrome (functional imbalance). Sagittal imbalance in combination with appropriate clinical symptoms may require surgical correction of the spine with fixation. However, in some cases, patients experience spontaneous correction of sagittal balance after isolated decompression without any correction or fusion. Therefore, it is necessary to clarify whether isolated decompression may cause spontaneous correction of sagittal imbalance in patients with degenerative lumbar stenosis.

Inclusion Criteria:

• 1. Age 45 and over;
• 2. Radicular leg pain and/or neurogenic claudication with/without back pain, caused by single- or multi-level degenerative lumbar stenosis with/without spodylolisthesis, confirmed by MRI;
• 3. Planned isolated decompression of the spinal canal without implantation of any devices;
• 4. Symptoms persisting for at least 3 months prior to surgery;
• 5. Given written Informed Consent;
• 6. Able and agree to fully comply with the clinical protocol and willing to adhere to follow-up schedule and requirements.

Non-Inclusion Criteria:

• 1. Prior any lumbar surgery;
• 2. Scoliosis of any non-degenerative etiology (due to vertebral fractures, idiopathic, etc.);
• 3. Degenerative scoliosis > 20 degrees;
• 4. Any contraindication or inability to undergo baseline and/or follow up MRI or X-ray as required per protocol;
• 5. Any other condition or situation that the investigator believes may interfere with the safety of the subject or the intent and conduct of the study;

Exclusion Criteria:

• 1. Performed intraoperative discotomy;
• 2. Performed intraoperative iatrogenic instability of the lumbar segment (facetectomy, foraminotomy, etc.)