In Vivo Measurement of Lumbar Facet Joint Area in Asymptomatic and Chronic Low Back Pain Subjects

Study Design. In vivo measurement of lumbar facet joint surface area. Objective. To investigate lumbar facet joint surface area in relation to age and the presence of chronic low back pain. Summary of Background Data. Facet joint surface area is an important parameter for understanding facet joint function and pathology, but information on the lumbar facet joint is limited, especially in relation with age and low back pain symptoms. Methods. In vivo measurements of the lumbar facet joints (L3/L4-L5/S1) were performed on 90 volunteers (57 asymptomatic subjects and 33 chronic low back pain subjects) using subject-based 3-dimensional facet joint surface computed tomography models. Results. The facet joint surface area increased significantly at each successive inferior level. In the low back pain subjects aged >40 years, both superior and inferior facet surface areas increased except superior facets at L5/S1 compared with younger subjects. In the asymptomatic subjects aged >40 years, only the superior facets showed an increase in the L3/4 facet surface area compared with younger subjects. Conclusion. The lumbar facet areas measured in vivo in this study were similar to previous cadaveric studies. The lumbar facet area was significantly greater at the inferior lumbar levels and also increased with age. This age-related increase in the facet joint surface was observed more in the low back pain subjects compared with asymptomatic subjects. The increase in the area of the facet joint surface is probably secondary to increased load-bearing in the lower lumbar segments and facet joint osteoarthritis.