Volumetric Bone Mineral Density Differences between Femurs of Scoliotic Patients: A Quantitative CT Study

Purpose or Learning Objective: Evidence of a difference between two femurs in a scoliotic patient is supposedly due to the presence of a loading imbalance on the lower limbs. Our aim was to investigate if a significant difference in areal bone mineral density (aBMD) and volumetric BMD (vBMD) exists between femurs in patients with scoliosis and whether this difference is related to spine convexity. We also compared such differences in patients without scoliosis.

Methods or Background: Abdominal computed tomography (CT) examinations were reviewed retrospectively. We used the so-called asynchronous calibration of the CT images to obtain BMD values from quantitative computed tomography (QCT). Differences between aBMD and vBMD of femurs were assessed using the Student t test and Wilcoxon's signed rank test, according to data distribution. Scoliosis was evaluated on the anteroposterior CT localizer to calculate the Cobb angle.

Results or Findings: Our final study cohort consisted of 391 subjects, 334 of them without scoliosis (85.5%) and 57 with scoliosis (14.5%). BMD comparison between the left and right femur of scoliotic patients, without considering the side of scoliosis, showed no statistically significant differences at all sites. When considering the convexity or concavity of the scoliotic curve, we found a statistically significant difference at the total femur, for both aBMD (− 0.038 g/cm²; p = 0.009) and vBMD (− 9.2 mg/cm³; p = 0.009). Total aBMD and vBMD values were lower on the convexity side.

Conclusion: The present study demonstrated that a difference in femoral BMD exists between the two femurs of scoliotic patients undergoing QCT analysis of the hip. If these data are confirmed by a larger study, bilateral femoral dual X-ray absorptiometry acquisition may be proposed for these patients.

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Artikel online veröffentlicht:
02. Juni 2022