Analysis of Risk Factors for Adjacent Segment Disease After Lumbar Facet Joint Fusion.

OBJECTIVE

Insufficient correction of segmental lordosis is an important risk factor for adjacent segment disease (ASD). This study aimed to investigate the relationship between segmental lordosis-related parameters and ASD following lumbar facet joint fusion (FJF).

METHODS

A retrospective analysis was conducted on 29 patients who underwent revision surgery for ASD after posterior lumbar fusion at our institution between February 2014 and February 2024. A matched control group of 29 non-ASD patients was selected based on age at initial surgery, sex, fusion level, and follow-up duration. Preoperative, postoperative, and final follow-up lumbar radiographs were analyzed. Parameters assessed included lumbar lordosis (LL), segmental lordosis (SL), sacral slope (SS), and relative disc height of adjacent segments. General baseline characteristics, sagittal parameters before and after the initial surgery, and correction values of sagittal alignment were compared between the two groups. Parameters showing significant differences were further analyzed using binary logistic regression, and receiver operating characteristic (ROC) curves were used to determine predictive thresholds of independent risk factors for ASD.

RESULTS

There were no significant differences in baseline characteristics between the two groups (p > 0.05). After the primary fusion surgery, LL and SS were significantly lower in the ASD group compared with the control group (p < 0.05). Regarding sagittal correction, the relative change in SL (r△SL) was significantly smaller in the ASD group (p < 0.05), confirming insufficient local curvature reconstruction. Logistic regression identified r△SL as an independent risk factor for ASD (p = 0.004, OR = 0.976, 95% CI: 0.960-0.992). ROC curve analysis revealed an area under the curve (AUC) of 0.712 (95% CI: 0.580-0.844), with an optimal predictive threshold of 2.6% for r△SL.

CONCLUSION

Insufficient correction of segmental lordosis is a key risk factor for ASD following lumbar facet joint fusion, and prioritizing the restoration of local sagittal alignment during surgery may effectively reduce the incidence of postoperative ASD.