Currently there is no consensus on the best surgical treatment of patients with symptomatic isthmic spondylolisthesis (IS). Clinical equipoise exists amongst experienced clinicians on the various surgical techniques available.

This study will involve multiple phases to answer specific research questions comparing anterior and posterior interbody fusion in patients with lumbar isthmic spondylolisthesis. The primary end point will be 1-year proportions of patients reaching minimal clinically important difference (MCID) in terms of leg pain measured by NRS leg. The secondary endpoints will be predetermined moderate to severe AEs, reoperations for nonunion, symptomatic adjacent segment disease, radiological alignment correction and correlation with HRQOL as well as economic analysis at 1, 2, 5 and 10 years.

Inclusion Criteria:

• Male or female aged 18 years or older (or who have reached the age of majority in the participating province)
• Require surgical treatment for a diagnosis of single-level lumbar isthmic spondylolisthesis, any grade, in the lumbar and lumbosacral spine.
• Are able to communicate in English or French
• Anterior interbody fusion group will be defined as having had an anterior or oblique approach with a synthetic cage insertion, interbody bone graft without cage or plate-screw construct with or without posterior rod-screw construct
• Posterior interbody fusion group will have only posterior approach procedure.

Exclusion Criteria:

• Previous spinal surgery

• Specific pathology at level above and below:

  • Degenerative anterolisthesis
  • Pars defect above or below index level

Adult patients with lumbar isthmic spondylolisthesis requiring surgical treatment