Reduction of degenerative anterolisthesis using an expandable interbody device.

Background: Degenerative spondylolisthesis is a condition characterized by back pain and radiculopathy due to nerve root impingement caused by misalignment of adjacent vertebral bodies. Surgical intervention with interbody fusions has been shown to have better outcomes than non-surgical approaches. Traditionally, static implants have been used to aid in arthrodesis of the unstable joint. A recent development in interbody fusion procedures is the use of expandable interbody devices which can expand bidirectionally to conform to endplate irregularities. This allows the spine to decompress naturally to fit each patient's unique anatomy, restoring spinal alignment and reducing spondylolisthesis in an individualized manner. Previous expandable interbody devices were regarded as inferior to their static counterparts due to high rates of non-union. The emergence of newer expandable implants that use a polyester mesh composed of polyethylene terephthalate thread has provided similar rates of fusion among both types of implants. The primary objective of this study was to illustrate the reduction of grade I/II degenerative anterolisthesis through a percutaneous trans-Kambin triangle far lateral approach using a single implant composed of a polyethylene terephthalate thread. Methods: A retrospective chart review was performed on patients who received an oblique far lateral trans-Kambin triangle percutaneous approach with placement of the studied implant to correct a grade I or II spondylolisthesis from 2/9/2018 to 5/26/2021. Demographic information was recorded from the electronic medical record system. Spondylolisthesis slip distance, foraminal height, anterior disc height, and posterior disc height were documented for both the pre-operative and post-operative radiographs. Results: For the 20 patients included in the study, the mean pre-operative spondylolisthesis was 5.2 mm, and the mean post-operative spondylolisthesis was 1.1 mm. The average change in spondylolisthesis was 4.1 mm, an 85.4% reduction. Sixty-five percent of the patients had complete reduction of spondylolisthesis with a post-operative measurement of 0 mm. Significant improvements were also observed in foraminal height as well as anterior and posterior disc height. Conclusions: The use of the expandable interbody device using a far lateral trans-Kambin approach displayed exceptional ability to reduce grade I/II degenerative spondylolisthesis. Radiographically, this surgical combination provided excellent, long-term decompressive abilities regarding foraminal height, disc height, and spondylolisthesis reduction.