The Prevalence of Adding-On or Distal Junctional Kyphosis in Adolescent Idiopathic Scoliosis Treated By Anterior Spinal Fusion to L3 was Significantly Higher Than By Posterior Spinal Fusion to L3.

Objective: To compare and identify risk factors for distal adding on (AO) or distal junctional kyphosis (DJK) in adolescent idiopathic scoliosis (AIS) treated by anterior- (ASF) and posterior spinal fusion (PSF) to L3. Methods: AIS patients undergoing ASF vs. PSF to L3 from 2000-2010 were analyzed. Distal AO and DJK were deemed poor radiographic results. New stable (SV) and neutral vertebra (NV) scores were defined for this study. The total stability (TS) score was the sum of the SV and NV scores. Results: 20 of 42 (ASF group: 47.6%) and 8 of 72 (PSF group: 11.1%) patients showed the poor radiographic outcome. Fused vertebrae, correction rate of main curve, coronal reduction rate of L3 were significantly higher in PSF group. Multiple logistic regression results indicated that preoperative SV-3 at L3 in standing and side benders (odd ratio = 2.7 and 3.7, respectively), total stability score -5, -6 at L3 (odd ratio = 4.9), rigid disc at L3-4 (odd ratio = 3.7), LIV rotation > 15° (odd ratio = 3.3), LIV deviation >2 cm from CSVL (odd ratio = 3.1) and ASF (odd ratio = 13.4, P<0.001) were independent predictive factors. There was significant improvement of the of SRS-22 average scores only in PSF group. Furthermore, the ultimate scores of PSF group were significantly superior to ASF groups. Conclusion: The prevalence of AO or DJK at ultimate follow-up for AIS with LIV at L3 was significantly higher in ASF group. Ultimate SRS-22 scores were significantly better in PSF group.