Correlation between direction of pedicle screw and restoration of lumbar degenerative scoliosis in degenerative lumbar spondylolisthesis: a retrospective study

Quantitative Imaging in Medicine and Surgery, 2023 · DOI: 10.21037/qims-22-483 · Published: March 1, 2023

Simple Explanation

This study investigates how the direction of pedicle screws affects the correction of lumbar degenerative scoliosis in patients with degenerative lumbar spondylolisthesis (DLS). DLS involves the slippage of a lumbar vertebra and can be accompanied by scoliosis due to disc degeneration. The research focuses on a surgical technique called transforaminal lumbar interbody fusion (TLIF), where screws are used to correct alignment. The study aims to determine if adjusting the angle of these screws can improve the restoration of spinal alignment in these patients. The findings suggest that angling the lower pedicle screw upwards (cranially) during TLIF surgery may help improve the correction of spinal curvature in patients with both DLS and lumbar degenerative scoliosis.

Study Duration

July 1, 2015, to April 30, 2021

Participants

57 patients with degenerative lumbar spondylolisthesis and lumbar degenerative scoliosis

Evidence Level

Not specified

Key Findings

1
TLIF surgery appears effective in improving radiographic and clinical outcomes for patients with DLS and lumbar degenerative scoliosis.
2
The cranial angle of the lower pedicle screw positively correlated with the restoration of intervertebral height difference (Δintervertebral height difference).
3
Multivariable linear regression analysis showed a positive impact of ΔDVR (change in degree of vertebral rotation) and preoperative DWA (disc wedging angle) on ΔIHD (change in intervertebral height difference).

Research Summary

This retrospective study analyzed 57 patients with degenerative lumbar spondylolisthesis (DLS) and lumbar degenerative scoliosis who underwent single-level unilateral transforaminal lumbar interbody fusion (TLIF) surgery. The study found that TLIF surgery improved clinical outcomes (VAS and ODI scores) and radiographic parameters. Specifically, a cranial angle of the lower pedicle screw correlated with better restoration of intervertebral height difference. Mediation analysis revealed that the angle of the lower pedicle screw influenced the restoration of intervertebral height difference indirectly through its effect on the degree of vertebral rotation.

Practical Implications

Surgical Technique Optimization

Surgeons can consider angling the lower pedicle screw upwards (cranially) during TLIF to potentially improve the correction of spinal curvature in patients with DLS and lumbar degenerative scoliosis.

Preoperative Assessment

Preoperative disc wedging angle (DWA) should be considered as it impacts postoperative correction of asymmetric intervertebral space.

Understanding Spinal Biomechanics

The study provides insights into the biomechanical effects of pedicle screw direction on spinal alignment, which can inform future research and surgical planning.

Study Limitations

1
The study has a relatively small sample size (57 patients) and is retrospective in design.
2
The flexibility of polyaxial pedicle screws might weaken the effect of spondylolisthesis reduction and restoration of asymmetric intervertebral space compared to monoaxial pedicle screws.
3
The follow-up period of approximately 1 year may be insufficient to detect long-term complications.

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