【Introduction】

The facet joints constitute a joint complex with the intervertebral discs and contribute to load distribution and control of excessive rotation. In most cases, degeneration of the lumbar spine occurs in the discs before the facet joints at the same spinal level, however, in a few cases, the facet joints degeneration (FJD) precedes the disc degeneration (DD) (FJD>DD). The purpose of this study was to investigate the prevalence of FJD>DD using epidemiological data. 

【Methods】

This is community-based cross-sectional study. The subjects were 437 community residents (142 males and 295 females, mean age 65.0 years) who underwent lumbar spine MRI in the 2004. We evaluated the left and right FJD from L1-L2 to L5-S using the Weishaupt classification (4 grades from 0-3). Disc degeneration was measured by the Schneiderman classification (4 grades from 0-3). We defined FJD>DD as Weishaupt grade ≥2 in either the left or right facet joint, and Schneiderman grade=0 at the same spinal level. We investigated the distribution of FJOA>DD at each spinal level from L1-2 to L5-S in three age groups: <50 years old, 50-60, and ≥60. Chi-square test was used for statistical examination, and P<0.05 was considered as statistically significant.

【Results】

A total of 219 subjects were enrolled, excluding those with compression fractures, scoliosis or degenerative spondylolisthesis. The distribution of FJD>DD at each spine level is as follows: L1-L2 (7/218=3.2%), L2-L3 (4/219=1.8%), L3-L4 (1/219=0.5%), L4-L5 (5/219=2.3%), L5-S (5/203=2.5%), p=0.34. The distribution between 3 age groups was as follows: L1-L2 (<50 vs 50-60 vs ≥60, 1/20=5.0% vs 4/37=10.8% vs 2/161=1.2%, p=0.01), L2-L3 (2/20=10.0% vs 2/37=5.4% vs 0/162=0.0%, p=0.001), L3-L4 (0/20=0.0% vs 1/37=2.7% vs 0/162=0.0%, p=0.09), L4-L5 (1/20=5.0% vs 1/37=2.7% vs 3/162=1.9%, p=0.66), L5-S (1/19=5.3% vs 2/34=5.9% vs 2/150=1.3%, p=0.04). The distribution between males and females for each level was as follows: L1-L2 (male vs female, 4/77=5.2% vs 3/141=2.1%, p=0.22), L2-L3 (3/77=3.9% vs 1/142=0.7%, p=0.09), L3-L4 (1/77=1.3% vs 0/142=0.0%, p=0.17), L4-L5 (5/77=6.5% vs 0/142=0.0%, p=0.002), L5-S (3/74=4.1% vs 2/129=1.6%, p=0.27).

【Discussion】

In the present study, subjects with FJD>DD were found in very small numbers at each lumbar level, and younger males tended to have FJD>DD. The pathogenesis and clinical significance of this condition need to be investigated in the future.