Aims: The aims of this study were (1) to determine the prevalence of the IISI in patients with DCM; (2) to investigate individually the prevalence and distribution of disc degeneration, height loss, osteophyte formation, endplate sclerosis, spondylolisthesis, segmental instability and spinal stenosis; (3) to address the association between radiological parameters and IISI.
Methods: A retrospective study was performed by measuring X-ray and MRI of 45 consecutive patients with DCM. The measurements on X-ray include disc height, horizontal intervertebral displacement, Torg-Pavlov ratio, rotational angle, C2-C7 Cobb angle, cervical sagittal vertical axis, segmental alignment, T1 slope and facet joint degeneration. Measurements on MRI include presence of IISI on MRI, posterior disc bulge, Pfirrmann classification, maximum spinal cord compression, maximum canal compromise, Modic changes, foraminal stenosis, cervical tilt, and cranial tilt. Methods used for the statistical analysis include independent T-test to calculate mean radiographic degeneration for each gender and point-biserial correlation coefficient to assess the correlation between patient/level-specific IISI and radiographic degeneration. Fisher’s test, Phi and Cramer’s V and point-biserial correlation coefficient were used to assess the independence, strength of association and strength of linear relationship respectively between presence of IISI and radiographic degeneration.
Results: A total of 45 patients with DCM (18 males, 27 females; age: 55.27±15.86) remained in the study with 19 (42.2%) patients having IISI in T2WI. There were 9 IISI at the level of C4-5, 7 at the level of C5-6, 6 at the level of C3-4, 5 at the level of C6-7, 3 at the level of C2-3, and 2 at level C1-2. There was no significant difference in presence of radiological DCM parameters between patients with IISI and patients without IISI.
Conclusions: The prevalence of IISI constituted 19 of 45 DCM patients studied and was most prevalent at the C4-C5 level. The presence of radiographic DCM parameters was not associated with IISI in the cervical spine with no significant difference found between IISI patients and non-IISI patients.