Radiographic Analysis of Endplate Coverage of a 3-Dimensional-Expandable Transforaminal Lumbar Interbody Fusion...

Transforaminal lumbar interbody fusion (TLIF) has become a mainstay technique for interbody fusion, allowing for large contact area between implant and endplate, and providing increased stability and greater area for fusion. The development of 3-dimensional (3D)-expandable implants that provide multidimensional (3D) expansion has shown to provide better height restoration and clinical outcomes when compared to static implants. Comparison of the endplate coverage between 3D-expandable and static TLIF implants has yet to be studied. This study compares endplate coverage achieved with static TLIF, 3D-expandable TLIF, and anterior lumbar interbody fusion (ALIF) implants.

A retrospective review of patients undergoing interbody fusion with either static TLIF, 3D-expandable TLIF, or ALIF between the years 2014 and 2022 was conducted. Postoperative computed tomography (CT) imaging was used to measure endplate and implant dimensions. 3D-expandable TLIF interbody device areas were calculated using diameter measurements on postoperative CT. The coverage ratio was defined as the ratio of twice the area of the implant and the sum of the superior and inferior endplate areas at the operative level.

A total of 53 patients per cohort were included. The average endplate coverage ratios for static TLIF, 3D-expandable TLIF, and ALIF implants were 0.19±0.04, 0.35±0.06, and 0.46±0.13, respectively. Subgroup analysis showed comparable coverage of 3D-expandable TLIF to ALIF implants at L3-4 and L4-5, while ALIF remained superior at L5-S1.

3D-expandable TLIF interbody devices provide greater endplate coverage when compared to static TLIF devices and approach comparable coverage to ALIF implants.