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Multilevel Oblique Lumbar Interbody Fusion in Degenerative Lumbar Disc Disease with Instability
Published on: July 25, 2025
Cage Overhang Ratio and Increased Radiographic Subsidence in Stand-Alone Lateral Lumbar Interbody Fusion
Samuel H Wakelin1, Nicole Don2, Benjamin J Carnovale2
1Department of Neurosurgery, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
World Neurosurgery
|June 26, 2026
Summary
Increased endplate overhang in lateral lumbar interbody fusion (LLIF) cages is linked to higher rates of implant subsidence. Minimizing cage overhang by matching endplate length can reduce subsidence, improving long-term outcomes.
Area of Science:
- Spine surgery
- Orthopedics
- Minimally invasive spine procedures
Background:
- Lateral lumbar interbody fusion (LLIF) is a common minimally invasive technique for spinal fusion.
- Implant subsidence is a potential complication following LLIF.
- Understanding factors influencing subsidence is crucial for optimizing patient outcomes.
Purpose of the Study:
- To evaluate the impact of endplate overhang on long-term radiographic implant subsidence after stand-alone LLIF.
- To identify specific cage characteristics associated with subsidence.
Main Methods:
- Retrospective review of 144 patients (218 levels) who underwent LLIF between 2014-2022.
- Calculation of overhang ratio based on cage and endplate dimensions.
- Radiographic assessment of implant subsidence using Marchi criteria.
- Statistical analysis using Firth regression to identify predictors of subsidence.
Main Results:
- Univariate analysis showed PEEK cage material, overhang, overhang area, and overhang ratio were associated with increased subsidence.
- Lateral plate fixation was associated with decreased subsidence.
- Multivariable regression confirmed age, PEEK cage material, lateral plate fixation, and overhang ratio as significant factors influencing subsidence.
Conclusions:
- Higher overhang ratio in LLIF cages correlates with increased radiographic subsidence.
- Selecting cages that closely match endplate dimensions, thereby minimizing overhang, can reduce subsidence rates.
- Optimizing cage selection is key to mitigating long-term implant subsidence in LLIF.