[Assessment of cortical bone material distribution in medial column of proximal humerus with computed tomography]

Objective: To evaluate the cortical bone characteristics in the medial column of proximal humerus. Methods: A total of one hundred and three healthy adults who underwent shoulder computed tomography scanning in Tianjing Hospital were included in this study.The subjects were divided into three groups according to the age: group A (20-39 years), group B (40-59 years), and group C (>60 years). Cortical bone mapping (CBM) was used to analyze ordinary clinical CT scans using Stradwin 5.2 software.Colors thickness maps were created for each proximal humerus.The region of interest (ROI) 1-6 were set at three levels of the lateral and medial column of proximal humerus.Cortical thickness (CTh), cortical mass surface density (CMSD), and endocortical trabecular bone mineral density (ECTD) were assessed in the three slices in proximal metaphysis.The impact of age, gender to the cortical bone indices of medial column of proximal humerus were investigated with relative analysis.Cortical indices of the lateral and medial column were compared with independent samples t test. Results: In ROI 2 and 3, men had higher cortical bone values than women, and significant differences in ECTD and CMSD were found in ROI 2, 3 and ROI 2 (t=2.100, 2.238, 2.530, all P<0.05). The lineal regression analysis showed that all cortical indices in ROI 1-3 decreased significantly with age for both women and men (r(2)=0.042-0.248, all P<0.05). In group A-C, the medial columns had higher CTh and CMSD values than lateral sides in plane 1, although significant differences were found only in group A (t=3.696, 3.749, both P<0.05). The highest CTh, CMSD and ECTD of the medial compact bone was detected in ROI 1, followed by ROI 2 and 3 in group A (F=5.867, 6.776, 19.062, all P<0.05). The medial columns had approximately equivalent cortica indices values in ROI 1-3 in group B and C. Conclusion: It indicated that significant regional variation in all cortical parameters exists in the medial column of proximal humerus, and the indices are influenced by gender and age.