Facet Joint Angle in Lumbar Spine: comparative study between HNP and spinal stenosis and control group

Lee, Kyu Yeol; Sohn, Sung Keun; Kim, Sang Beum; Lee, Hyung Hwan

Abstract

The importance of facet joint asymmetry has been debated as a cause of the low back pain and sciatica. And many studies have been proposed about the relationship between facet joint angle or facet joint asymmetry and the development of the disc degeneration or disc herniation. In the diagnosis of the spinal disorder, we have been used mainly myelogram and computed tomography. Several years ago, more advancement has been achieved by use of magnetic resonance image (MRI). Author studied the relationship between the facet joint angle and facet joint asymmetry and the development of the herniated nucleus pulposis (HNP) or spinal stenosis by comparision of the facet joint angle and facet joint asymmetry in each groups. Author reviewed the patients who were diagnosed as HNP or spinal stenosis with computerized tomography (CT) or MRI and treated with operative method at the department of orthopaedic surgery, Dong-A University Hospital. Facet joint angles were measured on the mid-disc cut, which was parallel to the inferior vertebral end-plate of the superior vertebra. The angles were measured by a midsagittal line through the disc and intersecting lines formed by conneqting the two end points of each facet. Facet joint asymmetry was determined by the difference between right and left facet joint angles. The results were compared between each groups and comparison group and statistical analysis was performed with the Kruskal- Wallis test in 95% confidence interval. The patients had only one level involved and had no other spinal disorder. 85 cases of HNP (central in 35 cases and lateral in 50 cases) and 50 cases of spinal stenosis were evaluated. The results were as follows: l. At the level of L4-5, the mean facet joint angles (+/-SD) were 42.50+/-5.52 (Rt.), 46.71+/-9.68 (Lt.) in central HNP, 40.91+/-9.11 (Rt.), 41.23+/-8.51 (Lt.) in lateral HNP, 37.77+/-11.41 (Rt.), 37.95+/-11.91 (Lt.) in spinal stenosis and 42.38+/-5.07 (Rt.), 41.25+/-5.85 (Lt.) in control group. 2. At the level of LS-S1, the mean facet joint angles were 48.83+/-5.64 (Rt.), 48.17+/-4.62 (Lt.) in central HNP, 52.20+/-11.30 (Rt.), 51.60+/-9.06 (Lt.) in lateral HNP, 42.67+/-8.89 (Rt.), 43.50+/- 9.85 (Lt.) in spinal stenosis and 43.91+/-7.88 (Rt.), 43.76+/-7.81 (Lt.) in control group. 3. At the level of L4-5, the mean facet asymmery was 6.35+/-6.04 in central HNP, 6.95+/-6.76 in lateral HNP, 6.47+/-5.56 in spinal stenosis and 4.31+/-5.42 in control group. 4. At the level of L5-S1, the mean facet asymmetry was 4.95+/-5.18 in central HNP, 4.72+/-5.25 in lateral HNP, 5.50+/-4.83 in spinal stenosis and 4.42+/-4.96 in control group. In conclusion, there were no statistically significant relationships between the magnitude of the facet joint angle and development of the HNP and spinal stenosis, and between the facet asymmetry and development of the HNP and stenosis.