Static Versus Expandable Devices Provide Similar Clinical Outcomes Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

  • Benjamin Khechen
  • Brittany E. Haws
  • Dil V. Patel
  • Joon S. Yoo
  • Jordan A. Guntin
  • Kaitlyn L. Cardinal
  • Sravisht Iyer
  • Kern SinghEmail author
Original Article



Few studies have analyzed differences in radiographic parameters and patient-reported outcomes (PROs) between expandable and static interbody devices in patients undergoing minimally invasive transforaminal lumbar interbody fusion (MIS TLIF).


To evaluate differences in radiographic parameters and PROs following MIS TLIF between static and expandable interbody devices.


Patients undergoing primary, single-level MIS TLIF between 2014 and 2017 were retrospectively identified. Radiographic measurements including lumbar lordosis (LL), segmental lordosis (SL), disc height (DH), and foraminal height (FH) were performed on lateral radiographs before and after MIS TLIF with a static or expandable articulating interbody device. Radiographic outcomes and PROs were compared using paired and unpaired Student’s t test.


Thirty patients received expandable interbody devices and 30 patients received static interbody devices. The expandable device cohort exhibited significantly greater improvement in DH and FH at final follow-up compared with those receiving a static device. Both device cohorts experienced significant improvements in PROs at 6 months post-operatively.


MIS TLIF with an expandable interbody device led to a greater increase of DH and FH than with a static interbody device. Patients undergoing MIS TLIF can expect similar improvements in PROs whether receiving a static or an expandable interbody device. Further studies are required to better understand improvements in clinical outcomes afforded by expandable interbody devices.


minimally invasive transforaminal interbody fusion interbody device expandable static patient-reported outcomes radiographic outcomes lordosis disc height foraminal height 


Compliance with Ethical Standards

Conflict of Interest

Benjamin Khechen, BA, Brittany E. Haws, MD, Dil V. Patel, BS, Joon S. Yoo, BA, Jordan A. Guntin, BS, Kaitlyn L. Cardinal, BS, and Sravisht Iyer, MD, declare that they have no conflicts of interest. Kern Singh, MD, reports royalties from Zimmer, Stryker, Pioneer, Lippincott Williams & Wilkins, Thieme, Jaypee Publishing, and Slack Publishing; stock ownership in Avaz Surgical, LLC, and Vital 5, LLC; board membership and a grant from Cervical Spine Research Society; board membership at the International Society for the Advancement of Spine Surgery, American Academy of Orthopaedic Surgeons, Scoliosis Research Society, and Vertebral Column–ISASS, all outside the submitted work.

Human/Animal Rights

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1975, as revised in 2013.

Informed Consent

Informed consent was waived from all patients for being included in this study.

Required Author Forms:

Disclosure forms provided by the authors are available with the online version of this article.

Supplementary material

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Copyright information

© Hospital for Special Surgery 2019

Authors and Affiliations

  1. 1.Department of Orthopaedic SurgeryRush University Medical CenterChicagoUSA

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