In Vivo Anatomical Research by 3D CT Reconstruction Determines Minimum Acromiohumeral, Coracohumeral, and Glenohumeral Distances in the Human Shoulder: Evaluation of Age and Sex Association in a Sample of the Chinese Population

Abstract

Accurate measurement of the minimum distance between bony structures of the humeral head and the acromion or coracoid helps advance a better understanding of the shoulder anatomical features. Our goal was to precisely determine the minimum acromiohumeral distance (AHD), coracohumeral distance (CHD), and glenohumeral distance (GHD) in a sample of the Chinese population as an in vivo anatomical analysis. We retrospectively included 146 patients who underwent supine computed tomography (CT) examination of the shoulder joint. The minimum AHD, CHD, and GHD values were quantitatively measured using three-dimensional (3D) CT reconstruction techniques. The correlation between minimum AHD, CHD, and GHD value and age with different sexes was evaluated using Pearson Correlation Coefficient. The mean value of minimum AHD in males was greater than that in females (male 7.62 ± 0.98 mm versus female 7.27 ± 0.86 mm, p = 0.046). The CHD among different sexes differed significantly (male 10.75 ± 2.40 mm versus female 8.76 ± 1.38 mm, p < 0.001). However, we found no statistical differences in GHD with different sexes (male 2.00 ± 0.31 mm versus female 1.96 ± 0.36 mm, p > 0.05). In terms of age correlation, a negative curve correlation existed between age and AHD among the different sexes (male R2 = 0.124, p = 0.030, female R2 = 0.112, p = 0.005). A negative linear correlation was found in CHD among the different sexes (male R2 = 0.164, p < 0.001, female R2 = 0.122, p = 0.005). There were no differences between age and minimum GHD in both sexes. The 3D CT reconstruction model can accurately measure the minimum AHD, CHD, and GHD value in vivo and is worthy of further investigation for standard clinical anatomical assessment. Aging may correlate with AHD and CHD narrowing for both sexes.

Keywords: acromiohumeral distance; computed tomography; coracohumeral distance; glenohumeral distance; shoulder joint; three-dimensional reconstruction.

Figure 1

Definition of shoulder measurement axes and angles. (a) All subjects were supine in the CT scan tunnel. (b) We define the angle between the axis of the proximal humerus (L2) and the line of the spinous process of the spine (L1) as the angle of abduction of the upper limb. (c) The level of the center of the humeral head is defined as the level of the median image slice between the most cranial and the most caudal (L3) slice with an identifiable anatomic neck of the proximal humerus. (d) We measured the rotation angle of the humerus at the level of the center of the humeral head-the angle between the axis of the humeral head (L5) and the line of bone between the anterior and posterior edges of the glenoid cavity (L4). Patients’ CT scans with upper limb abduction angle (the angle between L1 and L2) and humeral rotation angle (the angle between L4 and L5) greater than or equal to 10° were excluded because of the association between AHD alteration and upper limb abduction angle.

Figure 2

Flowchart diagram of this study. A total of 1713 patients underwent standard CT examinations of the shoulder joint and a total of 146 patients were eventually included in the study.

Figure 3

Representative 3D surface models reconstruction and segmentation of CT images of the proximal humerus and scapula. (a) Preparation of the proximal humerus and scapula for reconstruction on CT images. (b) Bone surface model of the scapula and proximal humerus. (c) The 3D surface models of the proximal humerus, acromion, coracoid process, and glenoid cavity. (Not-to-scale).

Figure 4

Representative determination of the minimum distance in the 3D surface models. The red areas indicate where (a) the acromion, (b) the coracoid process, and (c) the glenoid with the minimum distance from the humeral head. The sequential color change process from red to yellow, green, and blue represents a gradual increase in the distance between the two surface models. The minimum distance indicates that any point in the acromion, coracoid process, and glenoid cavity surface model can be reached at any point in the humeral head surface model which was automatically calculated. (Not-to-scale).

Figure 5

Statistical relationships among ages in both sex and statistical comparation between sexes for AHD, CHD, and GHD. a, b, and c indicate the letter marking method for the comparison between each age group within the group. * Indicates a significant difference in the comparison of the receiving female group p < 0.05. AHD acromiohumeral distance, CHD coracohumeral interval, GHD glenohumeral distance.

Figure 6

Curve correlation and Linear regression analyses of AHD and CHD. Curve correlation analyses representing the relationships between the CHD and ages in both sexes. Linear regression analyses representing the relationships between the CHD and ages in both sexes. AHD acromiohumeral distance, CHD coracohumeral interval.