Lowest Instrumented Vertebra at L3 Versus L4 in Posterior Fusion for Moderate Lenke 5C Type Adolescent Idiopathic Scoliosis: A Case-Match Radiological Study

Abstract

Objective: To compare the radiological outcomes in Lenke 5C type patients whose lowest instrumented vertebra (LIV) was L3 or L4 in a case-match study.Methods: We conducted a retrospective case-match study and included 82 patients in the study. Radiological results before surgery, after surgery, and at last follow-up were recorded and analyzed in the L3 and L4 groups.Results: After matching the age, Risser’s sign, sex, and main Cobb, 41 pairs of patients were enrolled in our study. The total fusion segments in the L3 group (median [interquartile range]: 5.0 [6.0–5.0]) were shorter than those in the L4 group (6.0 [6.5–6.0]). The main curve was significantly corrected after surgery in both groups, and was comparable at the last followup between groups. In addition, according to the results of Fisher precision probability test, there was no significant difference of coronal or sagittal imbalance between the 2 groups at the 2-year follow-up.Conclusion: The correction in coronal and sagittal planes in L3 group and L4 group remains similar. On account of more motion segments, L3 could be an ideal choice as LIV in moderate Lenke 5C type AIS. Long-term follow-up is needed to evaluate the effect of larger compensatory lumbar-sacral curve when stopping at L3.

Hyper‐Selective Posterior Fusion is Recommended When the Modified S‐Line is Positive in Lenke 5C Adolescent Idiopathic Scoliosis

“…Therefore, LIV at LEV was gradually accepted. 24 Sun et al 25 concluded that neither LIV = LEV group nor LIV = LEV+1 group corrected Lenke 5C curves differently. Chang et al 26 , 27 , 28 reported that L3, the LEV, could be selected as LIV with a flexible curve, while it was recommended to extend the LIV to L4 if the curve was rigid.…”