Quantifying cervical spondylosis: reliability testing of a coherent CT-based scoring system

BACKGROUND: Grading of degeneration of the cervical spine is of great clinical value, considering the vast amount of radiological investigations that are being done with this query. Despite the fact that Computed Tomography (CT) is frequently used in clinical practice there is today no user-friendly and reliable scoring system for assessment of cervical spondylosis on CT-scans available. The aim of this study was to establish a scoring system for cervical spondylosis based on CT-scans and to test it for reliability. METHODS: Twenty adult patients undergoing CT of the cervical spine due to neck pain following a motor vehicle accident were included in the study. Three independent raters, i.e. one orthopedic surgeon and two radiologists, assessed their CT-scans. Two of the raters repeated the assessments after three months. A radiographic-based scoring system for cervical disc degeneration, addressing disc height, osteophytes and endplate sclerosis, was applied on CT and tested for reliability. A pre-existing, reliable CT-based scoring system for facet joint degeneration, considering joint space narrowing, osteophytes and irregularity of the articular surface was modified and reevaluated. This in order to develop a coherent CT-based total degeneration score for cervical spondylosis. RESULTS: The scoring systems for cervical disc degeneration and facet joint degeneration both exhibited an acceptable or better level of strength of agreement regarding intra- and interrater agreement. The total disc degeneration score showed a moderate level of inter-rater reliability with a kappa-value of 0.47 and a good intra-rater agreement with intra-class correlation coefficients (ICC) of 0.67 and 0.60 for the two raters performing the assessments. The total facet joint degeneration score showed a moderate level of inter-rater reliability (kappa 0.54) and an excellent intra-rater agreement with ICC 0.75 for one of the raters and fair for the other rater (ICC 0.54). When the total disc and facet joint degeneration score were classified into a three-point total degeneration score the inter-rater agreement was 0.695 and the ICC 0.82 and 0.73 respectively. CONCLUSIONS: This coherent scoring system assessing both disc degeneration and facet joint degeneration on CT-scans of the cervical spine was shown to meet the standards of reliability.