Asymmetric Osteopenia in Adolescent Idiopathic Scoliosis Based on Hounsfield Unit of Computed Tomography

Purpose: To characterize the asymmetrical loss of bone mass and identify the association between scoliosis and osteopenia in patients with adolescent idiopathic scoliosis (AIS).
Methods: Demographic information, Cobb angle, and Hounsfield unit (HU) of the neutral vertebra (NV) and apical vertebra (apex) of the major curve were collected retrospectively in 54 AIS patients. For 84 control subjects, HU values were measured at T12 and L5. Propensity score matching was performed to balance the interference of age and BMI.
Results: In the AIS group, the concave and convex lateral HU of the NV and the convex lateral HU of the apex were negatively correlated with the Cobb angle. The AIS patients had lower bilateral HU. The mean HU and the apex-convex HU were also lower in the AIS group, while the apex-concave HU was slightly higher. After matching, the apex-convex HU of the AIS group remained lower, while the apex-concave HU was higher.
Conclusion: Patients with AIS exhibit osteopenia, particularly on the convex side. The severity of scoliosis was found to be directly proportional to the severity of bone loss and the degree of bilateral osteopenia asymmetry. Appropriate intervention for bone loss may be able to curb the progression of scoliosis.

Keywords: adolescent idiopathic scoliosis, osteopenia, osteoporosis, Hounsfield unit, propensity score matching