To evaluate angulations of facet joints related, transverse interfacet angle(TIFA), transverse interlaminar angle(TILA) and facet angle(F4), by computed tomography in lower lumbar spines, one hundred thirty-six cases taken CT scan because of low back pain were studied. The patients studies were composed of 68 normal group and 68 abnormal group revealed disc herniation at lower lumbar spine. And relationship between disc herniation and facet joint asymmetry was evaluated.

There are gradual increase in TIFA and TILA from L3/L4 downward and gradual decrease in FA for L3/L4 downward. At the level of L3/L4, the facet joints and laminae are more sagittally oriented, while at L5/S1 they are more frontally oriented. The angles at L4/L5 were intermediate in theirorientations. Facet joints with lumbar disc herniation were more sagittally oriented at L3/L4 and L4/L5, significantly.

Incidence of asymmerty of facet joins (tropism) was 36.8%, but no significant difference of the incidence of tropism between groups with disc herniation and not was noted.