Static vs. Expandable PEEK Interbody Cages: A Comparison of One-Year Clinical and Radiographic Outcomes for One-Level TLIF

Introduction: Degenerative spine disease is a disabling condition affecting many worldwide. Transoforaminal lumbar interbody fusion (TLIF) procedures help stabilize the spine, while improving back and/or leg pain. With the introduction of new implant designs and modifications, focus has shifted to optimizing spinopelvic alignment, fusion rates, and more. This study aims to explore the effect of static versus expandable polyetheretherketone (PEEK) cages on patient-reported outcomes (PROMs) and radiographic outcomes (subsidence, disk height, and alignment parameters). Materials/Methods: A retrospective cohort study was conducted using a database of patients in a single, high volume academic center. Patient outcomes were obtained from charts and radiographic outcomes were measured using standing, lateral radiographs. Data were analyzed using mean sample t-tests or categorical chi-squared tests, and multiple linear regression where appropriate. Results: Our results showed improved Oswestry Disability Index (ODI) scores perioperatively in the expandable cage group compared to the static cage group at the three-month and one-year time periods. In addition, there were a significantly greater proportion of patients that reached minimal clinically important difference (MCID) in the expandable group compared to the static cage group. There were no significant changes in subsidence or alignment parameters between the two groups at the one-year time period. Conclusion: Overall, our results show that TLIF patients treated with expandable PEEK cages had significantly greater improvement in one-year outcomes compared to patients with static cages. Expandable cages confer the advantage of more precise insertion into the intervertebral disk space, while providing a way to tailor the cage height for better distraction and spinal alignment. Further prospective studies are warranted to get a better idea of the impact of interbody design on clinical/radiographic outcomes

Static v. Expandable TLIF Cage Outcomes

Static cages were introduced in the 1990s as a solution to degenerative spondylolisthesis, recurrent disc herniation and spinal stenosis. As this procedure was popularized, a new class of expandable Transforaminal Lumbar Interbody Fusion devices was introduced to further improve outcomes that will be studied in this project. It will be explored how expandable cages compare to static cages in TLIF procedures in patient-reported outcomes, complications and restoration of appropriate lumbar lordosis. We conducted a retrospective cohort review comparing those who received expandable and static cages. Eligible patients received TLIF procedure at the Rothman Institute, were ≥18 years of age and had radiographic follow-up at 3 months and 1 year postoperatively. Outcomes were measured in lumbar lordosis via calculating angles via radiographic images preoperatively and 3 month and 1 year postoperatively as well as pre- and post-operative SF-12 surveys. At this time, data acquisition is ongoing and no preliminary data has been generated. However, we anticipate better patient reported outcomes and greater and sustained restoration of Lumbar Lordosis in patients who received expandable cages. Data collection is scheduled to be completed shortly. Once completed, this will be a study of greater magnitude and will address the shortage of investigations into the surgical outcomes of static and expandable cages and clarify the theorized benefits of expandable cages. Recent emphasis has been placed on restoring appropriate lumbar lordosis in fusion surgeries and this project was designed to investigate lordosis at different time posts as compared to patient-reported outcomes