Evaluation of screw density in Lenke type 1 adolescent idiopathic scoliosis: are low and high-density constructs truly comparable?

PURPOSE: Adolescent idiopathic scoliosis (AIS) affects 3% of adolescents, with Lenke 1 curves comprising 40% of cases. All-screw (AS) constructs provide adequate curve correction and maintenance in the coronal plane. Low-density (LD) screw constructs may offer comparable deformity correction, reduced implant density, and lower costs compared to high-density (HD) constructs. This study compares LD and HD screw constructs in Lenke 1 AIS, analyzing radiographic and surgical outcomes.

METHODS

The study included 86 pediatric patients with Lenke 1 AIS curves (Cobb angle < 80°), treated between January 2019 and September 2022, with a minimum 2-year follow-up. The primary outcome was the coronal correction rate (CR) of scoliosis curves. Secondary outcomes included loss of correction, perioperative complications, surgery duration, blood loss, length of hospital stay (LOS) and implant-related costs. Statistical analysis was performed using a permutation test, Mann-Whitney, Kolmogorov-Smirnov, and Chi-Squared tests, with significance set at 0.05.

RESULTS

The mean CR was 76.2 ± 9.1% for the HD group and 74.8 ± 10.4% for the LD group (p > 0.05). No significant differences were found in the loss of coronal correction or LOS. LD constructs resulted in shorter surgery durations (238 ± 5.1 vs. 255.9 ± 31.3 min, p < 0.05), less blood loss (470.2 ± 198.4 vs. 600.3 ± 263.5 mL, p < 0.05) and lower total cost of the implants (7460.6 ± 757.3€ vs. 8891.9 ± 783.8€, p < 0.05). The LD group had higher perioperative complications (8.1% vs. 2.7%) and major complications.

CONCLUSIONS

No significant differences were observed in post-operative and last follow-up coronal and sagittal correction. The LD group demonstrated reduced blood loss, shorter operative times, and lower implant costs, albeit with a higher incidence of perioperative complications. Future studies should explore implant distribution, rather than implant density, to ultimately optimize postoperative outcomes in the treatment of Lenke 1 AIS curves.