The correlation between radiographic and pathologic grading of lumbar facet joint degeneration

BACKGROUND Before performing spine non-fusion surgery that retains the facet joints, choosing an accurate radiographic method to evaluate the degree of facet joint degeneration is extremely important. Therefore, the objective of this study was to determine the accuracy and reliability of different radiographic classifications by analyzing the correlation between radiographic and pathologic grading of lumbar facet joint degeneration. Taking the pathologic examination as standard, the consistency of computed tomography (CT) and magnetic resonance imaging (MRI) assessment of lumbar facet joint degeneration was compared. METHODS A total of 74 facet joints obtained from 42 patients who underwent posterior lumbar surgery were evaluated. All patients underwent CT and MRI before surgery. The pathologic grade was evaluated with a method based on hematoxylin-eosin and toluidine blue staining. The radiographic grade was evaluated using the methods proposed by different authors. RESULTS There was a moderate consistency between pathologic and radiographic grading for facet joint degeneration. The weighted kappa coefficients comparing pathologic with radiographic grading were 0.506 for CT, 0.561 for MRI, and 0.592 for CT combined with MRI, respectively. Taking the pathologic examination as standard, the consistency of CT and MRI examination was also moderate, and the weighted kappa coefficient was 0.459. CONCLUSION The radiographic examination has moderate accuracy and reliability for evaluating degeneration of facet joints. Therefore, a more accurate method for evaluating the degeneration of facet joints is necessary before performing spine non-fusion surgery that retains the facet joints.