Fractures of the clavicle are common, accounting for 3% to 10% of all fractures and 35%–44% of fractures to the shoulder girdle [
For the displaced shaft fractures, the traditional opinion has been that they rarely require operative stabilization. However, more recent studies, over the last ten years, have demonstrated the disadvantages of nonoperative treatment. The relatively high number of nonunions, weakness, persistent pain, and disappointing cosmetic results might lead to unsatisfactory results in conservatively treated patients, while the results of primary operative reduction and fixation have improved considerably [
Open reduction and internal plate fixation and intramedullary fixation are two of the most commonly used surgical techniques for treating displaced shaft fractures. Due to the complex and variable bony anatomy of the clavicle, an understanding of clavicular anatomy is paramount for optimal plate design and fracture fixation. Several anatomical studies of the clavicle have been performed in western population in recent years [
52 patients (13 with pneumonia, 5 with lung bullae, 7 with lung tumor, and 27 with chest trauma) who underwent chest CT scan were included in the present study. None of the patients had previous fracture of clavicle. The average age was
Patients were scanned using a light speed 16 pro spiral CT scanner (GE, Connecticut, USA) with 0.625 mm CT slices at 300 mA and 120 kV. The images were imported into the ADW4.2 work platform. Three-dimensional reconstructions of the clavicles were generated.
A reference coordinate system was established to measure the geometric features of the 3D reconstructed clavicle. The line that passed through central points of two articular surfaces was defined as the
Several parameters were measured using the projection plane of the 3D clavicle into the Length of the clavicle ( Width of the clavicle in the axial plane: one line is perpendicular to the anterior surface of the clavicle and passes through one point of the anterior surface and another point of the posterior surface. The distance between these two points was defined as the width of the clavicle in the axial plane. The largest width at the sternal end ( Curvature of the clavicle in the axial plane:
Radius of curvature: the medial and lateral curvatures were fitted with circles most clearly suggesting an arc of curvature and their radii were measured ( Intersegmental angles: medial apex, lateral apex, and the central points of the sternoclavicular end and acromioclavicular end were connected with three lines; and these lines created intersegmental angles. The angle between the medial and middle segments was defined as Depth of the curvature: one line connects the most posterior point of the medial end and the apex of the posterior edge of the lateral curvature. The perpendicular distance from the apex of the posterior edge of the medial curvature to this line was defined as the depth of the medial/sternal curvature ( Several parameters were also measured using the projection plane of the 3D clavicle into the Thickness of the clavicle in the coronal plane: one line is perpendicular to the superior surface of the clavicle and passes through one point of the superior surface and another point of the inferior surface. The distance between these two points was defined as the thickness of the clavicle in the coronal plane. The largest thickness at the sternal end ( Curvature of the clavicle in the coronal plane: according to the superior curvature of the clavicle in the coronal plane, the clavicles were divided into four types: type 1, horizontal; type 2, convex, always on the acromial end; type 3, concave, always on the sternal end; type 4, S-shaped. One line connects two end points of the superior curvature. The perpendicular distance from the apex of the superior curvature to this line was defined as the height of the superior curvature ( Along the
Measurements of the length (
Measurements of the width and curvature of the clavicle in the axial plane.
Measurements of the intersegmental angles and depth of the curvature in the axial plane.
Measurements of the thickness of the clavicle in the coronal plane.
Measurements of curvature in the coronal plane.
Measurements of the areas of the intramedullary canal (S) and sectional areas of the clavicle (OS).
To test the interobserver and intraobserver variability of measurements, the parameters of 10 patients were measured by two observers (Wang XB, QIU XS) on two different occasions.
The statistical analysis was performed by SPSS 13.0 for Windows. Pearson’s rank correlation coefficients were used to assess measurement variability. Two-sample
The mean length of the clavicles was
The length, width, thickness, and curvature of the clavicle in Chinese population.
Measurements | Total | Male | Female |
|
Left | Right |
|
---|---|---|---|---|---|---|---|
Length | |||||||
|
144.2 ± 12.0 | 152.9 ± 9.3 | 135.6 ± 7.2 |
|
144.9 ± 11.9 | 143.5 ± 12.2 |
|
|
39.7 ± 8.4 | 42.2 ± 8.4 | 37.2 ± 7.7 |
|
40.0 ± 8.8 | 39.3 ± 8.1 |
|
|
61.5 ± 7.1 | 64.5 ± 7.3 | 58.5 ± 5.3 |
|
60.8 ± 6.8 | 62.2 ± 7.7 |
|
|
43.5 ± 8.7 | 46.8 ± 8.9 | 40.2 ± 7.2 |
|
44.2 ± 9.5 | 42.7 ± 7.8 |
|
Width in the axial plane | |||||||
|
22.1 ± 3.6 | 24.1 ± 3.2 | 20.2 ± 2.8 |
|
21.9 ± 3.9 | 22.3 ± 3.3 |
|
|
11.4 ± 2.1 | 12.7 ± 1.7 | 10.2 ± 1.3 |
|
11.4 ± 1.9 | 11.5 ± 1.9 |
|
|
22.7 ± 4.1 | 25.1 ± 3.6 | 20.3 ± 2.9 |
|
22.6 ± 4.2 | 22.8 ± 4.0 |
|
Thickness in the coronal plane | |||||||
|
20.8 ± 6.0 | 21.1 ± 7.5 | 20.6 ± 4.1 |
|
21.1 ± 6.2 | 20.5 ± 5.8 |
|
|
10.5 ± 1.9 | 11.7 ± 1.9 | 9.3 ± 1.0 |
|
10.5 ± 1.6 | 10.5 ± 2.2 |
|
|
14.1 ± 3.8 | 16.3 ± 3.8 | 11.9 ± 2.2 |
|
14.0 ± 3.9 | 14.2 ± 3.7 |
|
Curvature in the axial plane | |||||||
|
63.2 ± 12.1 | 66.4 ± 12.8 | 60.0 ± 10.6 |
|
63.4 ± 12.6 | 62.9 ± 11.8 |
|
|
29.4 ± 8.2 | 28.8 ± 8.2 | 30.0 ± 8.1 |
|
29.0 ± 8.3 | 29.8 ± 8.1 |
|
|
17.4 ± 4.0 | 19.7 ± 3.0 | 15.2 ± 3.6 |
|
17.3 ± 3.7 | 17.5 ± 4.3 |
|
|
12.7 ± 3.3 | 14.0 ± 3.5 | 11.3 ± 2.5 |
|
12.7 ± 3.5 | 12.6 ± 3.2 |
|
|
148.1 ± 5.4 | 146.7 ± 4.9 | 149.6 ± 5.6 |
|
148.7 ± 5.2 | 147.6 ± 5.6 |
|
|
146.6 ± 8.7 | 145.6 ± 9.4 | 147.6 ± 7.8 |
|
147.5 ± 8.9 | 145.7 ± 8.4 |
|
Curvature in the coronal plane | |||||||
Type 2 (convex) | |||||||
|
4.5 ± 1.7 | 4.9 ± 1.8 | 4.0 ± 1.4 |
|
4.9 ± 1.6 | 4.2 ± 1.8 |
|
Type 3 (concave) | |||||||
|
−5.7 ± 1.7 | −5.7 ± 1.9 | −6.0 ± 0.8 |
|
−6.3 ± 1.8 | −5.3 ± 1.5 |
|
Type 4 (S-shaped) | |||||||
|
−2.7 ± 1.0 | −3.2 ± 1.2 | −2.5 ± 0.9 |
|
−2.8 ± 1.2 | −2.7 ± 0.8 |
|
|
3.0 ± 1.4 | 3.2 ± 1.6 | 2.9 ± 1.3 |
|
2.9 ± 1.3 | 3.1 ± 1.5 |
|
The mean lengths of
In the axial plane, the largest mean width at the sternal end was 22.1 ± 3.6 mm and was located at 4.3 ± 0.9% of length, while the largest mean width at the acromial end was 22.7 ± 4.1 mm at 94.7 ± 1.2%. The largest mean width was significantly smaller in female than in male clavicles at both ends (
In the coronal plane, the largest mean thickness at the sternal end was 20.8 ± 6.0 mm and was located at 4.9 ± 1.2% of length, while the largest mean thickness at the acromial end was
In the axial plane, the clavicle showed an S-shaped appearance. The circle fitted within the medial curvature had a mean radius of
In the coronal plane, there were 3.8% (4/104) type 1 (horizontal), 32.7% (34/104) type 2 (convex), 13.5% (14/104) type 3 (concave), and 50.0% (52/104) type 4 (S-shaped) clavicles according to the superior curvature. The distribution of the curvature types was significantly different between males and females. For type 2, a convex curvature was present and the largest depth of the curvature was located at 63.4 ± 6.1% and measured as
The intramedullary canal decreased gradually from two ends toward the center where it became the smallest. The men’s medullary canals were larger than that of women. No significant difference was found between the two sides concerning the intramedullary canal. Similarly, the sectional areas of the clavicle decreased gradually from two ends toward the center. The men’s sectional areas were larger than that of women. No significant difference was found between the two sides concerning the sectional areas (Table
Intramedullary canal (S) and sectional areas (OS) of the clavicle.
Measurements | Total | Male | Female |
|
Left | Right |
|
---|---|---|---|---|---|---|---|
S1 | 200.3 ± 99.3 | 220.2 ± 103.5 | 180.3 ± 91.7 |
|
200.2 ± 103.5 | 200.4 ± 96.0 |
|
S2 | 77.1 ± 32.5 | 96.4 ± 28.0 | 57.7 ± 24.4 |
|
73.6 ± 31.8 | 80.6 ± 33.3 |
|
S3 | 53.1 ± 26.0 | 68.3 ± 25.1 | 37.8 ± 16.0 |
|
53.0 ± 26.2 | 53.2 ± 26.0 |
|
S4 | 36.1 ± 19.9 | 46.1 ± 18.6 | 26.0 ± 15.7 |
|
34.2 ± 20.2 | 37.9 ± 19.5 |
|
S5 | 44.0 ± 23.3 | 54.8 ± 24.2 | 33.2 ± 16.5 |
|
40.6 ± 21.0 | 47.4 ± 25.2 |
|
S6 | 65.4 ± 25.8 | 81.0 ± 22.9 | 49.8 ± 18.0 |
|
63.5 ± 24.1 | 67.3 ± 27.6 |
|
S7 | 102.8 ± 59.9 | 131.8 ± 67.5 | 73.7 ± 31.0 |
|
101.9 ± 51.8 | 103.6 ± 67.5 |
|
OS1 | 326.3 ± 122.7 | 364.3 ± 114.4 | 288.2 ± 119.8 |
|
330.9 ± 124.6 | 321.8 ± 121.8 |
|
OS2 | 175.7 ± 51.5 | 208.0 ± 39.3 | 143.5 ± 41.2 |
|
174.0 ± 53.0 | 177.4 ± 50.5 |
|
OS3 | 138.0 ± 40.6 | 167.6 ± 31.3 | 108.4 ± 23.8 |
|
138.7 ± 43.0 | 137.3 ± 38.4 |
|
OS4 | 121.6 ± 34.7 | 145.8 ± 27.4 | 97.3 ± 22.0 |
|
120.0 ± 34.8 | 123.1 ± 34.9 |
|
OS5 | 130.8 ± 40.2 | 155.3 ± 39.0 | 106.2 ± 22.6 |
|
124.6 ± 38.3 | 136.9 ± 41.5 |
|
OS6 | 165.3 ± 44.1 | 197.2 ± 35.4 | 133.5 ± 24.6 |
|
161.4 ± 40.0 | 169.3 ± 47.9 |
|
OS7 | 210.6 ± 78.9 | 258.7 ± 75.7 | 162.5 ± 46.1 |
|
207.0 ± 72.0 | 214.2 ± 84.9 |
|
The Pearson correlation coefficients of interobserver repeat measurements ranged from 0.96 to 0.99, and the Pearson correlation coefficients of intraobserver repeat measurements ranged from 0.94 to 0.99. All correlations were statistically significant, and the level of measurement reliability was excellent.
Midshaft clavicle fractures have traditionally been managed conservatively, but there is a reemergence of interest in operative fixation due to a number of reasons recent years [
To define the anatomical shape of the plate or to fix the fractured clavicle with intramedullary nails, a comprehensive understanding of the bony morphology is crucial. However, current morphologic studies focused on the western population [
The average clavicle length in our population was 144.2 mm, which is consistent with previous findings in western population (Table
Comparison of the clavicle morphology with the literature data.
Measurements | Groups | Present study | Mathieu, |
Bernat, |
Bachoura, |
Daruwalla, |
Huang, |
---|---|---|---|---|---|---|---|
|
Total | 144.2 ± 12.0 | 149.4 ± 10.3 | 136.7 ± 10.4 | 145.0 ± 12.7 | ||
Males | 152.9 ± 9.3 | 152.7 ± 2.9 | 155.8 ± 7.6 | 152.33 | 152.6 ± 10.2 | ||
Females | 135.6 ± 7.2 | 140.2 ± 1.5 | 142.9 ± 8.4 | 140.34 | 137.3 ± 10.2 | ||
|
|||||||
|
Total | 20.8 ± 6.0 | 25.6 ± 3.1 | ||||
Males | 21.1 ± 7.5 | 25.7 ± 3.7 | |||||
Females | 20.6 ± 4.1 | 25.4 ± 3.0 | |||||
|
|||||||
|
Total | 10.5 ± 1.9 | 9.5 ± 1.3 | ||||
Males | 11.7 ± 1.9 | 10.2 ± 1.2 | 11.69 | ||||
Females | 9.3 ± 1.0 | 8.7 ± 0.9 | 9.34 | ||||
|
|||||||
|
Total | 14.1 ± 3.8 | 13.6 ± 1.7 | ||||
Males | 16.3 ± 3.8 | 14.6 ± 1.5 | |||||
Females | 11.9 ± 2.2 | 12.7 ± 1.3 | |||||
|
|||||||
|
Total | 63.2 ± 12.1 | 66.4 ± 8.0 | ||||
Males | 66.4 ± 12.8 | 72.1 ± 1.4 | |||||
Females | 60.0 ± 10.6 | 68.7 ± 1.2 | |||||
|
|||||||
|
Total | 29.4 ± 8.2 | 33.5 ± 10.5 | ||||
Males | 28.8 ± 8.2 | 37.1 ± 1.2 | |||||
Females | 30.0 ± 8.1 | 37.8 ± 0.9 | |||||
|
|||||||
|
Total | 17.4 ± 4.0 | |||||
Males | 19.7 ± 3.0 | 18.4 ± 1.6 | |||||
Females | 15.2 ± 3.6 | 15.1 ± 1 | |||||
|
|||||||
|
Total | 12.7 ± 3.3 | |||||
Males | 14.0 ± 3.5 | 12.3 ± 1.5 | |||||
Females | 11.3 ± 2.5 | 10.2 ± 0.6 |
|
|
|
|
The lungs and subclavical artery are in close proximity to the clavicle. Knowing the width and thickness of the clavicle can be helpful to evaluate the screw length when anterior or superior plate and screw fixation are used. We measured the largest and smallest width and thickness of the clavicle in the axial and coronal planes. The results showed that the largest width and thickness located at the sternal end and acromial end, while the smallest width and thickness located at the clavicle shaft. Compared with Bernat et al.’s study [
In the axial plane, the clavicle showed an S-shaped configuration. Compared with western population (Table
In the literatures [
In conclusion, the results of this study provided an anatomical data of the clavicle in a Chinese population. These clavicle dimensions can be applied to the modifications of the contemporary clavicle plate or a newly development for the Chinese population. The statistics analysis also revealed significant differences in dimensions between male and female clavicle, indicating that distinguished designs for the genders may be required to improve bone-implant fitness.
The authors declare that they have no competing interests.
Xu-sheng Qiu and Yi-xin Chen participated in the study design. Xiao-bo Wang participated in patients’ data collection, CT scan, and 3D reconstruction. Yan Zhang, Xia Guo, and Yan-Cheng Zhu participated in data measurement. Xu-sheng Qiu was in charge of interpreting the data analysis and drafting of the paper. All authors read and approved the final paper.
This study has received financial support from the Peak Talents Foundation in Jiangsu Province (no. 2012-WS-092), Key Project of Department of Health, Nanjing, China (JQX12005), and the Key Program of Science and Technique Development Foundation in Jiangsu Province (BE20116004).