Postoperative improvement in leg length discrepancy in adolescent idiopathic scoliosis differs between right and left legs()

BACKGROUND: In adolescent idiopathic scoliosis (AIS) patients, leg length discrepancies (LLDs) often occur to compensate for scoliosis. However, there have been no reports on the LLD changes after corrective surgery for AIS. This study aimed to clarify the difference of LLD changes after corrective surgery for AIS by classifying LLD based on the shortened side. METHODS: We analyzed preoperative and postoperative radiographs of 94 consecutive AIS patients who underwent posterior corrective surgery between 2012 and 2018. The patients enrolled were divided into three groups according to the presence of preoperative LLD of more than 5 mm and the LLD side: the left leg shortened group (L group), the non-LLD group (N group), and the right leg shortened group (R group). The three groups were compared with regard to age, sex, Lenke classification, Risser grade, fused levels, and radiographic parameters before surgery and at 6-month follow-up (thoracic Cobb angle, lumbar Cobb angle, L4 tilt, coronal balance, T1 tilt, and LLD). RESULTS: The L, N, and R groups included 23 (24%), 60 (64%), and 11 patients (12%), respectively. The demographics and radiographic parameters were not significantly different among the groups except for preoperative L4 tilt. In the L group only, the LLD decreased from 7.9 ± 2.2 mm to 5.7 ± 3.7 mm (p = 0.002) after surgery. In contrast, the LLD in the N and R groups did not change significantly. CONCLUSIONS: The postoperative improvement of LLD in AIS patients differed between the left and right sides. Different pathologies may contribute to the LLD on the left and right sides.