The effect of coronal decompensation on the biomechanical parameters in lower limbs in adolescent idiopathic scoliosis.

STUDY HYPOTHESIS

We hypothesized that altered coronal balance in adolescent scoliosis leads to asymmetric stress on the lower limbs, with subsequent effects on bone maturation and later morphology. We aimed to assess the correlation between the biomechanical parameters of the lower limbs and coronal balance in idiopathic scoliosis.

MATERIALS AND METHODS

In this study, EOS images of 280 patients and 56 controls were randomly selected from our clinics' database. The average age of AIS patients was 14.5years and average Cobb angle 33.48°. Three D reconstructions of the pelvis and lower limbs were performed and coronal balance assessed. Reliability of measurements was ensured by intra- and inter-observer agreement. During statistical analysis the Kolmogorov-Smirnov test, t-test and linear regression analysis were performed. A p value <0.05 was considered significant.

RESULTS

Of the 15 examined lower limb parameters, a significant difference between sides was found in those with AIS for femur length, total length, collodiaphyseal angle, angle between the femoral mechanical and anatomical axis and tibial torsion. In addition, the tibial length and the mechanical tibiofemoral angle were significantly higher than those of the controls. The coronal balance was found to be the strongest predictive factor showing a significant correlation with all of the previous parameters, except tibial torsion. With patients grouped based on coronal balance (compensated, right and left decompensated) the paired t-test also supported these findings.

CONCLUSION

The biomechanical parameters of the lower limbs are affected in cases of scoliosis with an altered coronal balance. It was thought that a shift in balance in the coronal plane accounted for the small but significant changes seen in our study, with the lower limb on the side of decompensation becoming shorter in comparison to its' counterpart, with a lower collodiaphyseal angle and increased varus at the knee joint.

LEVEL OF EVIDENCE

III, case-control study.