Adjacent segment degeneration after superior facet joint violation of the lumbar spine

Facet joint violation (FJV) is a recognized complication of pedicle screw fixation and has been proposed as a driver of adjacent segment disease (ASD). Biomechanical models suggest that FJV may alter segmental kinematics, but its clinical impact on degeneration and reoperation remains uncertain. This work evaluates whether superior FJV is associated with an increased risk of radiographic ASD or reoperation after lumbar fusion.

Retrospective cohort study of patients undergoing lumbar pedicle screw fixation with postoperative CT imaging that captured the instrumentation and the cranial adjacent segment. Superior FJV was graded using an established 3-tier system. Follow-up imaging was assessed for disc height loss, progression of spondylolisthesis, coronal deformity, central stenosis, lateral recess height and a composite degeneration endpoint; reoperations were recorded. Propensity score weighting balanced measured covariates, and a weighted cox regression was used for time-to-event analyses.

Seventy-one patients met inclusion criteria, with FJV identified in 35 (49.3%). Weighted analyses demonstrated no significant association between FJV and disc height loss (HR 1.21, 95% CI 0.54-2.72), progression of spondylolisthesis (HR 0.59, 95% CI 0.13-2.65), coronal deformity (HR 2.18, 95% CI 0.48-10.01), central stenosis (HR 1.35, 95% CI 0.21-8.61), composite degeneration (HR 1.76, 95% CI 0.87-3.56), or reoperation (HR 0.44, 95% CI 0.12-1.62). Exploratory subgroup analysis suggested that minor (grade 1) violations may contribute to axial instability, whereas full joint traversal (grade 2) may confer relative stability, though neither reached statistical significance.

In this cohort with extended follow-up, superior FJV was not significantly associated with any measure of radiographic degeneration or reoperation. These findings suggest that FJV may not be a major determinant of long-term outcomes after lumbar fusion. Further biomechanical and clinical studies are warranted to clarify whether specific grades of FJV differentially affect cranial segment stability and screw performance.

Superior FJV on CT didn't significantly increase hazards of disc height loss, listhesis, stenosis, deformity, or reop after fusion.