The purpose of this study is to collect data regarding the safety and feasibility of the GO-LIF procedure for spinal fixation and stabilization, in conjunction with conventional approaches for interbody lumbar fusion. This is in order to allow for evidence-based comparison to pedicle-screw-based techniques as described in the literature.

Inclusion Criteria

1. Men and women, 18-80 years of age.
2. The capability to comprehend the nature and rationale of the study and to consent to participating in the study.
3. Unequivocal medical indication for the fixation surgery of a single motion segment of the lumbar spine.
4. Correct coronal profile of the lumbar spine. An asymmetric collapse of the disk space in the coronal plane between the vertebral bodies envisioned for instrumentation is by itself not an exclusion criterion.

Or any of criteria below:

1. Patients with Grade II or Grade III spondylolisthesis in the sagittal plane with preserved or normal sagittal alignment requiring single-level instrumented interbody fusion from L1 to S1. (Not excluding patient with a need to decompression)

2. Patients must have normal alignment of the spine in the coronal view. 2. The interbody fusion approach may be TLIF or PLIF or ALIF or other, as clinically indicated.

   3. The procedure may be combined with a Micro-decompression and/or Micro-discectomy and/or direct or indirect decompression and/or laminectomy or laminotomy and/or other procedures, as clinically indicated - as long as such procedures do not compromise the structural integrity of the pedicles of the inferior vertebra or the vertebral body of either vertebra of the levels involved..

   4. Patient is 18 years or more 5. Patient is willing and able to comply with study requirements

   Exclusion Criteria:

   1. Lumbar hyperlordosis > 70° between the end plate of the lumbar vertebral body 1 and the end plate of the sacral vertebral body 1.
   2. Deformities of the vertebral bodies envisioned for instrumentation or the sacrum.
   3. Spondylolisthesis > grade 2 acc. to Meyerding.
   4. Scoliosis and other deformities in the coronal plane.
   5. Fractures of the vertebrae envisioned for instrumentation.
   6. Osteoporosis or osteopenia (see below for examination criteria).
   7. Therapy with systemic corticosteroids or immunosuppressants.
   8. Bone metabolism diseases, such as osteomalacia or Paget's disease.
   9. Post inflammatory instability of the vertebral spine.
   10. State after radiation therapy of the relevant vertebral spine region.
   11. Current Marcoumar or heparin therapy for more than 6 months at the time of operation.
   12. Malignant diseases with or without bone metastases.
   13. Immunologic-inflammatory diseases (e.g., rheumatoid arthritis).
   14. Diabetes mellitus.
   15. Infectious diseases.
   16. BMI > 30.