Sonoanatomic indices of lumbar facet joints in patients with facetogenic back pain in comparison to healthy subjects

BACKGROUND: Nowadays, ultrasound is increasingly used with a great accuracy in performing nerve blocks for facet joint disease. OBJECTIVES: To measure sonoanatomic characteristics for the facet joints of lumbar vertebras in patients with facetogenic pain and healthy volunteers. STUDY DESIGN: Cross-sectional, observational study. SETTING: University-affiliated Specialty Clinic for Pain Management. PATIENTS: Twenty patients with facet joint disease (FJD) and 40 healthy volunteers (HVGs) were matched for age and sex, height, and weight. Patients with FJD were referred with complaints of pain in the left lumbar facet joints that twice responded favorably to ultrasound guided medial branch blocks. INTERVENTION: Medial branch blocks. MEASUREMENT: The interfacet joint distance (IFJD) between the third, the fourth, and the fifth lumbar vertebras and their depth from the level of skin (DFS) were measured bilaterally, using a high-resolution ultrasound in both groups. RESULTS: Thirty-one men and 29 women with average age of 41.5±9.5 years were enrolled. The IFJD for L3-L4 was 31.5±4.0 mm on the left side and 31.8±4.0 mm on the right side. The IFJD for L4-L5 was 31.3±4.4 mm on the left side and 31.5±4.0 mm on the right side. The IFJD was uniformly 2.2 mm shorter in the FJD group than those in the HVG group (P=.021). The measurements of DFS increased in lower vertebras (L3<L4<L5), bilaterally. With an exception of the left facet joints of L4 (P=.016), DFS measurements were similar in FJD and HVG groups. LIMITATIONS: The diagnosis of facet joint disease was merely clinical and the total number of the patients was relatively small. CONCLUSION: Interfacet distances of the lumbar vertebras are smaller in patients suffering from degenerative FJD compared with HVGs. Degenerative changes of intervertebral discs and partial reduction of space between 2 adjacent vertebras may contribute to this observation.