Study design: Cross-sectional study.

Objective: To investigate the relation between lumbosacropelvic morphology and the presence and degree of facet joint degeneration.

Summary of background data: Osteoarthritis of the facet joints is one of the most common degenerative changes in the spine. It is considered to be formed secondary to repetitive stress or trauma and spinal deformity with secondary overload. The cause(s) of facet joints osteoarthritis, however, have not been clearly identified.

Methods: Abdominal computed tomography (CT) images of 723 patients which were taken between the years 2010 and 2014 were evaluated retrospectively. Patients with prior lumbar spinal surgery, serious congenital anomalies on CT, incomplete or complete lumbosacral transition, severe scoliosis, were excluded from the study. To eliminate the age- and sex-related differences in spinopelvic morphology, a study group was formed of the remaining subjects by including patients from a specific age group (30-35 yr) and same sex (females). For each patient the presence and grade of facet joint degeneration was investigated. In addition, pelvic incidence (PI), sacral slope and the angles of L1-L5 lumbar lordosis, sacral table, L5 vertebra posterior, and sacral kyphosis were measured for each patient.

Results: Sacral slope, sacral kyphosis, and L1-L5 lumbar lordosis angle were significantly higher in patients with osteoarthritic compared with normal subjects (P = 0.015, P = 0.018, P = 0.016). L5 vertebra posterior and sacral table angle were found to be significantly lower in patients with osteoarthritic than in normal subjects (P = 0.019, P = 0.007). The degree of facet joint degeneration was noticed to increase parallel to the decrease in the sacral table angle and L5 vertebra posterior angle, and to the increase in the L1-L5 lumbar lordosis, PI, and sacral slope.

Conclusion: A close relation exists between the presence and degree of degeneration in the facet joint and lumbosacral pelvic morphology. Prevalence and degree of the degeneration in facet joint increases as the angle of sacral slope, L1-L5 lumbar lordosis, and PI increases or the angle of sacral table and L5 vertebra posterior decreases.

Level of evidence: 4.