Targeted anterior expansion of the cervical facet joints achieves indirect foraminal decompression and reduces spondylolisthesis via a posterior approach: a cadaveric study.

Abstract

In this cadaveric study, we aimed to assess the effects of distraction at the anterior end of the cervical facet joints (CFJ), achieved via a posterior cervical approach (PCA), on intervertebral neural foraminal height (IVFH) and segmental alignment. A novel cervical expandable facet implant (CeLFI) was used to facilitate anterior expansion within the CFJ. This study was conducted in three time periods (2018, 2019, and 2024). The CeLFI was primarily placed at the CSPL levels or at the non-fused C3-7 levels if no CSPL was present. Pre- and post-implantation outcomes were assessed using cervical spine radiography and computed tomography (CT) scan. Changes in facet joint space (FJS) height, IVFH, interspinous distance (ISD), intervertebral disc height (IVDH), and cervical alignment were assessed. CeLFI insertion (n = 12) resulted in an increase in the mean IVFH (+ 1.5 mm left; + 2 mm right, both p < 0.001), FJS height (+ 2.41 mm left; 2.53 mm right, both p < 0.001), ISD (+ 2.83 mm, p = 0.003), and posterior IVDH (+ 1.16 mm p = 0.001). In the cadavers with CSPL (n = 9), a segmental reduction was observed, which remained stable in flexion-extension radiographs. Two cadavers also showed unbuckling of the posterior interspinous ligaments on post-insertion CT. No significant changes in overall cervical alignment were observed after CeLFI insertion. Indirect cervical intervertebral foraminal decompression and reduction of cervical segmental spondylolisthesis were achieved via a PCA with targeted distraction at the anterior end of the CFJ. This novel concept is promising but requires further clinical studies to evaluate its benefit for patients with degenerative cervical spine disease.