Osteoarthritis of the facet joints: accuracy of oblique radiographic assessment.

TLDR

The study evaluated the sensitivity and specificity of lumbar spine radiography for facet joint osteoarthritis using CT as the reference standard. Two radiologists independently graded facet joint osteoarthritis on oblique radiographs and CT scans with a four‑point scale in 50 consecutive low‑back‑pain patients. CT showed 68% of facet joints abnormal and 28% moderate or severe, interobserver agreement was high, and oblique radiography achieved 55% sensitivity and 69% specificity overall, with 94% specificity but only 23% sensitivity for moderate/severe disease, making it useful for screening but less sensitive than CT.

Abstract

Sensitivity and specificity of lumbar spine radiography in the assessment of facet joint osteoarthritis were evaluated, with computed tomography (CT) as the standard. Two independent radiologists used a four-point scale to blindly grade facet joint osteoarthritis on oblique radiographs and transaxial CT scans obtained within an 8-month period in 50 consecutive patients with pain in the lower back. The L-3 to L-4, L-4 to L-5, and L-5 to S-1 facet joints were evaluated, and 68% appeared abnormal on CT scans, with 28% exhibiting moderate or severe disease. Interobserver agreement was high for conventional radiography (perfect agreement in 57% and agreement to within one grade in 39%) and still higher for CT (perfect in 63% and to within one grade in 35%). Receiver operating characteristic curve analysis indicated that oblique radiography was most accurate (55% sensitivity, 69% specificity) in distinguishing the presence from the absence of disease; in distinguishing absent or mild from moderate or severe disease, the specificity of oblique radiography was higher, at 94%, but its sensitivity was much lower, at 23%. Conventional radiography is a useful technique in screening for facet joint osteoarthritis but is insensitive compared with CT.