The purpose of the study is to gather clinical and radiographic outcome data from patients who have undergone treatment with an expandable interbody spacer.

This is a multi center retrospective study with 200 patients. Sites will screen their patient records for patients who have had a TLIF utilizing the CALIBER® expandable interbody spacer in conjunction with the REVOLVE® or REVERE® posterior stabilization systems and subsequent follow-up visits.

The study aims to collect both pre-operative and post-operative data at the 6, 12 and 24 month time points according to existing standard of care and the surgeon's custom and practice.

Inclusion Criteria:

• Objective evidence of degenerative disc disease at 1 or 2 level(s) between L2 and S1 resulting from degeneration of disc confirmed by history and radiographic studies.
• At least 18 years of age and maximum 80 years of age

Exclusion Criteria:

• • Presence of systemic or localized infection at the site of surgery

  • More than 2 levels to be instrumented
  • Previous fusion attempt at the involved level(s)
  • Spondylolisthesis unable to be reduced to Grade 1
  • Previous documentation of osteopenia, osteoporosis, or osteomalacia to a degree that spinal instrumentation would be contraindicated
  • Diagnosis of a condition or on postoperative medication(s), which may interfere with bony/soft tissue healing
  • Presence of a disease entity or condition which totally precludes possibility of bony fusion (e.g. metastatic cancer, HIV, long term use of steroids, etc.)
  • History of substance abuse (drugs or alcohol)
  • Mentally incompetent or prisoner

Both male and female between the ages of 18 and 80 with objective evidence of degenerative disc disease between L2 and S1 at 1-2 contiguous levels.

Once data collection is complete and analyzed, we will submit to journals for publication