Which lumbar vertebra should be the lowest level of fusion in adolescent idiopathic scoliosis of Lenke types 5 and 6?

Objective: It is important to protect the mobile segment in the lumbar region in scoliosis surgery. The aim of this study was to compare the clinical and radiological results of patients who underwent surgery for a diagnosis of adolescent idiopathic scoliosis (AIS) with the lowest instrumented vertebra (LIV) at L3 or L4 level.

Methods: The study included 36 patients who underwent surgical treatment in our institution for a diagnosis of Lenke type 5 and 6 AIS with a follow-up period of at least 24 months. The patients were separated into 2 groups according to the LIV level of L3 (n=21) and L4 (n=15). These 2 groups were compared preoperatively (PO), early postoperative (EPO), and at the final follow-up examination (last control (LC)) with respect to radiological parameters in the coronal and sagittal planes, and the Scoliosis Research Society - 22 (SRS-22) questionnaire values.

Results: In both groups the mean age (L3: 16 ± 7.3; L4: 17 ± 6.1 years) and follow-up periods (L3: 44 ± 20; L4: 47 ± 18 months) were similar. Radiologically, the L4 group had a greater Cobb angle in the scoliosis main curves measured PO (P=.001). The Cobb angles measured at EPO (P=.767) and at LC (P=.674) were similar in both groups. No significant difference was observed between the 2 groups in respect of the LIV tilt values at PO (P=.469), EPO (P=.297), and LC (P=.065). When the groups were evaluated separately, the LIV tilt values at EPO and LC were similar in the L4 group (EPO: 6.93 ± 3.058; LC: 7.26 ± 2.313; P=.618). In the L3 patients, although there seemed to be a significant increase in LIV tilt values when EPO values were compared with LC values (EPO: 8.47 ± 3.970; LC: 9.57 ± 3.76; P=.030), this was within the error range of Cobb angle measurement. The results of the SRS-22 questionnaire showed significantly better results in the L3 group in the domains of pain, function/activity, mental health, and satisfaction with treatment (P=.011, P=.002, P=.019, P=.046, respectively).

Conclusion: There was no radiological superiority between L3 and L4 LIV groups in the thoracolumbar/lumbar curve patients. However, according to the SRS-22 questionnaire, the results of patients with L3 level LIV were better in the areas of pain, function/activity, mental health, and satisfaction with treatment.

Cite this article as: Baymurat AC, Tokgoz MA, Abdulaliyev F, Tosun MF, Can MM, Senkoylu A. Which lumbar vertebra should be the lowest level of fusion in adolescent idiopathic scoliosis of Lenke types 5 and 6? Acta Orthop Traumatol Turc., 2024;58(2):116-123.