Facet joints arthrosis in normal and stenotic lumbar spines.

STUDY
DESIGN: A descriptive CT study of lumbar facet joint (FJ) arthrosis in general and spinal stenosis populations.
OBJECTIVE: To reveal the prevalence of FJ arthrosis in general and stenosis populations and to establish its relationship to age and sex. SUMMARY OF BACKGROUND DATA: FJ arthrosis is a common radiographic finding and has been suggested as a cause of low back and lower extremity pain. It is also considered a dominant player in the genesis of lumbar spinal stenosis. Although it is well accepted that FJ arthrosis is an age dependent phenomenon, controversies still exist as to its association with sex and its prevalence at different spine levels. In addition, data on FJ arthrosis frequency in spinal stenosis population are missing.
METHODS: Two groups were studied. The first included 65 individuals with LSS (mean age = 66 ± 10 yr) and the second, 150 individuals (mean age = 52 ± 19 yr) without LSS related symptoms. Both left and right FJ arthrosis for each vertebral level (L3-S1) were evaluated on CT images (Brilliance 64, Philips Medical System, Cleveland, OH). Chi-square, Linear-by-Linear Association and McNemar test were carried out to reveal the correlation between FJ arthrosis and demographic factors (age, sex) and prevalence at different lumbar levels in both stenosis and nonstenosis groups. In addition, a two-way analysis of variance (ANOVA) was used to determine the association between body mass index (BMI) and FJ arthrosis.
RESULTS: The rate of FJ arthrosis at L3-L4 and L4-L5 were significantly higher (P < 0.001) in the stenotic group compared to the control. In the control group the prevalence of FJ arthrosis increases cephalocaudally (L3-L4 = 16%, L4-L5 = 28%, L5-S1 = 55%), whereas in the stenotic group there is a sharp increase from L3-L4 (27%) to L4-L5 (58%), but not from L4-L5 to L5-S1 (55%). No association between FJ arthrosis and sex was noted. Although, mean BMI was significantly smaller in the control group compared to the stenotic group, no association between BMI and facet arthrosis was found. In the general population the prevalence of FJ arthrosis at all three levels was greater for the right side; however, significant difference (P = 0.004) was obtained only for L3-L4. In all joints studied, the prevalence of FJ arthrosis increases considerably from the young age cohort (18-39) to the old age cohort (>60). Nevertheless, 10% of the young individuals (18-39) have already manifested FJ arthrosis at L5-S1. No arthrosis at that age was observed at L3-L4.
CONCLUSION: FJ arthrosis is an age-dependent and BMI and sex independent phenomenon. In the general population, the prevalence of FJ arthrosis increases cephalocaudally with the highest frequency at L5-S1. In the stenotic group, the highest frequency was observed at the two caudal levels; L4-L5 and L5-S1. The prevalence of FJ arthrosis was greater for the right side.