Intrinsic Cortical Property Analysis of the Medial Column of Proximal Humerus.

OBJECTIVE

Adequate mechanical support of the medial column is paramount to maintain fracture reduction in locking plating of proximal humerus fractures. However, intrinsic cortical properties of the medial column are rarely discussed. The purpose of the study is to describe regional variation of cortex in the medial column.

METHODS

A total of 147 healthy participants were eligible for enrollment between December 2016 and December 2018. Subjects were divided into three groups: group A (20-39 years), group B (40-59 years), and group C (>60 years). For each individual, a color 3D thickness map for proximal humerus was created by cortical bone mapping (CBM) technique after bilateral shoulders were imaged by computed tomography. Measurement Indices including the cortical thickness (CTh), cortical mass surface density (CM) and the endocortical trabecular density (ECTD) were determined, after six regions of interest (ROI) were defined in metaphyseal region. Regional parameter variations were analyzed by one-way ANOVA.

RESULTS

The CTh, CM and ECTD values were approximately equivalent between genders in the proximal part of the medial column across all ages (P > 0.05).The greatest difference between sexes was found in CTh and CM values of middle and distal part (P < 0.05). The CTh and CM within medial column were negatively associated with age (P < 0.05). The proximal cortical bone of the medial column was thicker and more dense, compared to the lateral column (P < 0.05). Significant regional variation was found in all measured parameters in group A, but not in groups B and C.

CONCLUSION

Our finding proved that regional differences in the distribution of cortical bone in the medial column The attenuation of cortical bone heterogeneity in the medial column was found after the age of 40 years.