The Relationship of Facet Joint Orientation and Tropism with Lumbar Disc Herniation and Degenerative Spondylolisthesis in the Lower Lumbar Spine

STUDY DESIGN: Retrospective study. PURPOSE: This study aimed to clarify the relationship of both facet tropism (FT) and the sagittally aligned facet (SAF) joint with lumbar disc herniation (LDH) and degenerative spondylolisthesis (DS). OVERVIEW OF LITERATURE: Despite several studies conducted, there is no consensus on the association of the SAF joint and FT with DH and DS. METHODS: Between June 2015 and December 2017, magnetic resonance imaging scans of 250 consecutive patients who underwent surgery for LDH and DS were analyzed. The facet angles at all the lower lumbar levels were calculated, and SAF and FT were noted. The relationship between the side of disc herniation and that of the SAF joint were also determined. Statistical analysis was performed, and the relation of SAF and FT to LDH and DS was noted. RESULTS: We observed a positive relationship between SAF and LDH at L4–5 and L5–S1 with a p-value of 0.02 (<0.05). FT demonstrated a positive association with LDH at L4–5 (p=0.047) but not at L3–4 or L5–S1. SAF demonstrated a positive relationship with DS at L3–4 (p<0.001) but not at L3–4 or L5–S1. FT demonstrated a significant relation with DS at L4–5 (p<0.001), whereas no positive association was observed at L3–4 and L5–S1. CONCLUSIONS: The L4–5 level demonstrated a significant association with SAF and FT in LDH and DS. Moreover, SAF at L5–S1 demonstrated a positive association with LDH. These findings provide useful information for future longitudinal studies to elucidate the possible causes for such phenomena.