Selection of Lowest Instrumented Vertebra in Lenke 5 and 6 Adolescent Idiopathic Scoliosis

Study Design. Network meta-analysis. Objectives. To determine lowest instrumented vertebra (LIV) in Lenke 5 & 6 Adolescent Idiopathic Scoliosis (AIS) patients. Methods. An extensive literature search was carried out aimed at identifying articles reporting outcomes in Lenke 5 and 6 AIS patients based on LIV selection. Apart from the study characteristics and demographic details, the extracted data included lumbar and thoracic curve correction, LIV angle (LIVA) correction, LIV disc (LIVD) angle correction, LIV translation correction (LIVT), OT time, blood loss, patient reported outcomes and complications. The extracted data was analyzed; forest plot and surface under the cumulative ranking curve (SUCRA) plots were generated to draw comparisons between lower end vertebra (LEV), LEV-1, and LEV+1 groups. Results. Six studies were finally included for analysis. All six studies were case-control studies. Three studies compared LIV at LEV versus LEV+1, while the remaining three analyzed LIV at LEV versus LEV-1. The studies collectively analyzed 403 patients divided into LEV (225), LEV+1 (62), and LEV-1 (116) groups. No significant difference was found between the 3 groups with respect to the correction of cobb angle (lumbar, thoracic), LIVA, LIVT, ot time and blood loss. Significant difference was found only between LEV-1 versus LEV+1 with respect to LIVD angle correction. Adding on was seen in 1 pt in the LEV+1 group, 2 in LEV group, and 11 in LEV-1 group at 2 yr follow up in the included studies. Conclusion. This meta-analysis concluded that all three procedures are equally effective in radiological correction and patient-reported outcomes. However, selecting LEV-1 as LIV may lead to a higher risk of adding-on and distal disc wedging. While LEV is generally safe for most Lenke 5 and 6 curves, LEV+1 may be a more appropriate choice for cases with high preoperative LIVA, TL/L Cobb angle, LIVT, and rigid lumbar curves. Level of Evidence. II.