Purpose: Spinal fusion reduces flexibility, but we do not have detailed knowledge that accounts for growth or sex differences. We sought to determine trunk flexibility pre- and postoperatively in patients with adolescent idiopathic scoliosis (AIS).
Methods: We included data from 109 patients with AIS in this retrospective, single-center observational study. Patients had performed a sit-and-reach (SR) test preoperatively, and 1 and 2 years postoperatively, and measurements were standardized to Z scores according to age and sex. The patient data were divided into three groups according to the level of lower instrumented vertebra (LIV): (1) Group A (fusion above L2); (2) Group B (fusion to L2), and (3) Group C (fusion to L3 or L4). The change in the Z score for various levels was determined and compared.
Results: The preoperative Z score for all patients was -0.622. At 2 years postoperatively, the Z score in Groups A and B was not significantly different from the preoperative score; in Group C, the Z score decreased by 1 year postoperatively, improved during the second year, but remained significantly lower than the preoperative score. Our study was the first to assess trunk flexibility using the SR test in patients with scoliosis.
Conclusions: Preoperatively, patients with AIS had lower SR test Z-scores than the general population, indicating a lower trunk flexibility in these patients. At 2 years after surgery in these patients, trunk flexibility had returned to preoperative levels when LIV was at L2 or above, but when LIV was at L3 or L4, trunk flexibility was less than it was preoperatively.
Level of evidence: Prognostic Level II: retrospective study.
Keywords: Adolescent idiopathic scoliosis; Fusion; Lowest instrumented vertebra; Mobility.
© 2022. The Author(s), under exclusive licence to Scoliosis Research Society.