Increased and decreased pelvic incidence, sagittal facet joint orientations are associated with lumbar spine osteoarthritis in a large cadaveric collection

Purpose: Degenerative joint disease of the lumbar spine is a pervasive problem in healthcare; however, its aetiology and risk factors remain poorly defined. There have been recent attempts to correlate the anatomic parameters of facet angle and pelvic incidence with spine osteoarthritis, although data remains limited. The purpose of this experiment was to determine how age, gender, race, facet angle, tropism, and pelvic incidence correlate to facet joint osteoarthritis in the lumbar spine. Methods: A total of 576 cadaveric lumbar spines were obtained. Using validated techniques, facet angle, tropism, and pelvic incidence were measured. Osteoarthritis of the lumbar spines was graded from 0-4 at each level. Correlations between osteoarthritis and age, gender, facet angle, tropism, and pelvic incidence were evaluated with regression analysis. Results: Facet angle became more coronally oriented, and facet tropism increased from L1-L2 to L5-S1. Arthritis was highest at the L4-L5 joint (2.2 ± 1.1), compared to the L5-S1 (2.1 ± 1.1), L3-L4 (1.9 ± 1.1), L2-L3 (1.5 ± 1.0) and L1-L2 (1.0 ± 1.0) joints (p < 0.001). Age was the strongest predictor of arthritis at all levels (standardized betas 0.342 through 0.494, p < 0.001). Correlations between gender, race and osteoarthritis were not significant at any level. A decreased facet angle was predictive of increased arthritis at each joint level (standardized betas –0.091 through –0.153, p < 0.05 for all). Tropism was a predictor of increased arthritis at caudal levels. Pelvic incidence was a predictor of increased arthritis at L3-L4 (standardized beta 0.080, p = 0.02), L4-L5 (standardized beta 0.081,p = 0.02), and L5-S1 (standardized beta 0.100, p = 0.01). Conclusions: Facet arthritis was correlated with a more sagittal orientation of the facet joints, increased tropism, and perturbations of pelvic incidence.