McMaster University McMaster University Toronto, Ontario, Canada
Abstract Body : Introduction and Objective:
Spinal decompression surgery, a treatment for lateral stenosis of the lumbar spine, is linked with low success rates. This could be explained by potentially overlooked structures causing nerve impingement, such as the sublaminar ridge (SLR), the osseous attachment site for the ligamentum flavum. Given that CT imaging is the standard method of diagnosis for spinal stenosis, planar and 3D CT image reconstructions may be used to measure the SLR. These measurements may be used to inform clinical decisions around addressing SLR hypertrophy in cases of spinal stenosis. This study aims to develop a measurement protocol to quantitatively characterize the SLR on cadaveric lumbar spines using CT imaging and reconstruction.
Materials and Methods:
Lumbar spinal blocks were extracted from 15 cadavers. CT images were taken using a high-resolution protocol (slice thickness of 0.625 mm) to visualize the SLR through 3D reconstruction on Amira (Version 6.3, Thermofisher Scientific) and 2D planar images on Volume Viewer (General Electric). A measurement protocol was developed to measure the SLR in terms of its height, angle, and degree of stenosis in relation to the vertebral lamina. Measurements were completed by a team of 5 observers.
Results:
Preliminary data for 3D reconstructions (36 SLRs) were analyzed on SPSS (14). Mean ± SD for SLR height, angle, and degree of stenosis were 1.78 mm ± 0.56 mm, 23.9˚± 8.9˚, and 22.6% ± 1.3%, respectively. Moderate positive correlations were found between height and degree of stenosis (r = 0.555, p < 0.001) as well as between angle and degree of stenosis (r = 0.511, p = 0.001). Intra-class correlation coefficient estimates of 0.812 and 0.831 for SLR height and angle respectively indicate a good degree of inter-observer reliability. Four SLRs were excluded from analysis, as observers unanimously agreed that the SLR was not measurable.
Conclusion:
This study introduces a method to quantify the shape of the SLR, shedding insight into its role in spinal stenosis. Positive associations between the SLR’s height and angle to the degree of stenosis may be used to predict its impingement on exiting spinal nerves. Challenges with measuring poorly defined SLRs in 3D underscore the necessity for a standardized analytical approach.
Significance & Implication:
Assessment of SLR anatomy before spinal decompression surgery may enhance preoperative evaluations for lateral spinal stenosis patients to guide well-informed surgical strategies, and thus improve patient outcomes. The study’s impact extends to clinical practice, emphasizing the importance of SLR assessment in spinal interventions and demonstrating the need for a more comprehensive understanding of spinal anatomy.
