Leg length discrepancy and adolescent idiopathic scoliosis: clinical and radiological characteristics

Purpose This retrospective study aimed to present the clinical and radiological features of functional scoliosis due to LLD and LLD concurrent with AIS; it also aimed to define their relationships for differentiating functional scoliosis due to LLD and LLD concurrent with AIS. Methods This study was conducted as a single-center retrospective comparative study on 47 scoliosis patients with diagnosed LLD, aged 10–18 years. Cases with a diagnosis of structural LLD were divided into two groups according to the presence or absence of concurrent AIS. Data on demographics and the angle of trunk rotation on a sacral basis (ATR sacrum ) were recorded. Limb length was clinically measured with a tape measure and clinical LLD (C-LLD) scoliometer test. Cobb angle, axial rotation, pelvic obliquity, and radiological LLD (R-LLD) were obtained from standing spine radiographs and measured by two blinded orthopedic spine surgeons. Results The prevalence of LLD was 6.7% in scoliosis patients in our study population. Cobb angle and apical rotation were higher in the LLD concurrent with AIS group than in the LLD group ( p ≤ 0.05). The C-LLD scoliometer test results were strongly correlated with both C-LLD tape measure ( r = 0.651; p = 0.000) and ATR sacrum ( r = 0.688; p = 0.000). Conclusion LLD may develop as a result of adaptive changes due to scoliosis, or a concurrent condition to scoliosis. Cobb angle and apical rotation are the features that differentiate AIS from functional scoliosis in patients with LLD. The C-LLD scoliometer test can be an effective, practical, and useful method for measuring C-LLD, but its validity and reliability should be determined. Trial registration This study was retrospectively registered at ClinicalTrials.gov (number: NCT04713397, date of registration: 01/14/2021). Level of evidence III.