Frequency of sternal variations in living individuals

Sternal Morphologic Characteristics of U.S. Military Males by Computed Tomography: Implications for Intraosseous Access

INTRODUCTION

Sternal intraosseous (IO) access has advantages over humeral and tibial access for fluid resuscitation in military medical settings due to superior flow rates and pharmacokinetics. However, the morphology of the young adult manubrial cortical and medullary bone as it relates to IO catheter tips of currently available FDA-approved IO access devices is unclear.

MATERIALS AND METHODS

Computed tomography manubrium images of active duty service members (N = 93) aged 18 to 30 were assessed by radiologists, including manubrial height, width, and cortical thickness, as well as total thickness and medullary thickness at the thickest (superior) and thinnest (inferior) parts of the manubrium. Inference regarding medullary or cortical IO catheter tip placement rates were made for FAST1 (5.5 mm catheter depth) and TALON (4.5 mm catheter depth) sternal IO devices. Data were analyzed using ANOVA, non-parametric, and correlational statistics at P < 0.05.

RESULTS

As inferred from case-specific CT-derived manubrium dimensions and maximal catheter tip penetration depths, both FAST1 and TALON would be placed in the target medullary space on 100% of opportunities if properly applied in the superior manubrium and on 99% of opportunities if properly applied in the inferior manubrium. Age was not significantly related to IO-relevant manubrial dimensions.

CONCLUSIONS

Present findings suggest that both FAST1 and TALON sternal IO catheter tips can be successfully placed into the target medullary bone with high accuracy in male military members aged 18 to 30 who require rapid resuscitation.

Sternal foramina: An imaging study

To investigate the computed tomography (CT) image characteristics, adjacent tissues, and related measurement indices of the sternal foramina and provide an anatomical basis for the safety of minimally invasive sternum surgery. The data from 2500 thoracic multi-slice computed tomography (MSCT) cases from January 2020 to June 2021 were analyzed retrospectively. The number and location of the sternal foramina and adjacent tissues (mediastinal adipose tissue, lung, pericardium) were observed. The size of the sternal foramina, CT value of the tissue inside the foramina, subcutaneous adipose tissue thickness, distance from skin to lung, distance from skin to the pericardium, and manubrio-foraminal distance were measured. Sex differences were compared for each indicator performed. The incidence of sternal foramina was 4.44% (111/2500), with 83 males and 28 females. All sternal foramina were located at the mesosternum's fourth to sixth costal cartilage level. The transverse diameter of the sternal foramina was (0.60 ± 0.29) cm, and the vertical diameter was (0.68 ± 0.39) cm, which was greater in males than females (p > 0.01). The CT value of the tissue in the sternal foramina was (-77.05 ± 32.26) Hu, and there was no statistical difference between male and female patients (t = -1.780, p = 0.078). The adjacent tissues of the sternal foramina were only adjacent to adipose tissue in 41 cases (36.94%), pericardium in 18 patients (16.22%), lung tissue in 37 cases (33.33%), and both kinds of tissue in 15 cases (13.51%). The sternal foramina were not adjacent to the left lung in the female patients. In the sternal foramina region, the thickness of subcutaneous adipose tissue was (1.13 ± 0.51) cm, the distance from skin to lung was (1.86 ± 0.57) cm, the distance from skin to pericardium was (3.07 ± 0.72) cm, the manubrio-foraminal distance was (12.68 ± 1.31) cm, which was significantly greater in males than in females (p < 0.05). The sternal foramina are closely related to the heart and lungs. The size and location of sternal foramina, the thickness of subcutaneous adipose tissue, and the distance from skin to heart and lung are all crucial factors in evaluating the safety of sternal puncture biopsy.

Anatomical Variants Identified on Computed Tomography of Oropharyngeal Carcinoma Patients

Background and Objectives: Anatomical variations in the head, neck and chest are common, and are observed as occasional findings on computed tomography (CT). Although anatomical variations are mostly asymptomatic and do not cause any negative influence on the body function, they may jeopardize diagnosis and may be confused with pathological conditions. The presence of variations may also limit surgical access during tumor removal. The aim of this study was to investigate the prevalence of six anatomical variations—os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe and tracheal bronchus—in an open-access computed tomography dataset obtained from oropharyngeal cancer patients. Materials and Methods: A total of 606 upper-chest and neck computed-tomography scans (79.4% male and 20.6% female) were retrospectively investigated. Sex difference was evaluated using the z-test for two proportions. Results: Os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe, and tracheal bronchus were present in 3.1%, 2.2%, 0.2%, 0%, 0.3% and 0.5%, respectively, of all patients. Os acromiale was identified as meso-acromion in 86.6%, and as pre-acromion in 17.4%, of all acromia. Episternal ossicles were present unilaterally in 58.3%, and bilaterally in 41.7%, of all sterna. Only the cervical rib showed a sex difference in prevalence. Conclusions: awareness of these variations is important for radiologists interpreting head, neck and chest CTs; for example, those of oropharyngeal cancer patients. This study also illustrates the applicability of publicly available datasets in prevalence-based anatomical research. While most of the variations investigated in the present study are well-known, the episternal ossicles are not well explored, and need further investigation.

Prevalence and morphometry of sternal and xiphoid foramen: a meta-analysis on 16,666 subjects

PURPOSE

Sternal foramen is a perforation of the sternum that can be a source of misdiagnosis during radiographic imaging or life-threatening perforations during bone marrow sampling. The aim of this study was to conduct a meta-analysis on the prevalence, morphometrics, and location of foramen in the sternal body and xiphoid process, describe morphometric features of this phenomenon, and thus verify its clinical importance. Moreover, our secondary outcome was to compare effectiveness of various imaging methods in diagnosis of the sternal or xiphoid foramen.

METHODS

A comprehensive search was conducted on major scientific databases to identify studies containing relevant information. Data on foramen's prevalence, location, morphometrics, and accompanying findings were extracted and pooled into a meta-analysis using MetaXL 5.0.

RESULTS

Thirty-five studies (n = 16,666 subjects) were included. The overall pooled prevalence of a foramen in the sternal body and/or a xiphoid process was 8.9% (95% CI 6.5-11.7) and it equaled 6.5% (95% CI 5.6-7.6) for sternal body alone and 2.9% (95% CI 0.5-6.9) for the xiphoid process. The foramen was more prevalent in males than in females (12.2% vs. 6.8%). The prevalence of sternal foramen was higher in South American [13.9% (95% CI 11.2-16.9)] and African [13.6% (95% CI 9.7-18.0)] studies compared to North American [6.2% (95% CI 5.0-7.5)] and European populations [8.6% (95% CI 3.1-16.3)]. Mean transverse and vertical diameter of foramen equaled 4.7 mm (95% CI 3.8-5.5), and 5.6 mm (95% CI 4.2-6.9), respectively.

CONCLUSION

Our analysis proves that the sternal foramina are structures of significant prevalence and size. Any physician should keep them in mind when performing punctures in this area.

Evaluation of manubriosternal joint fusion and second costal cartilage calcification: Are they useful for estimating advanced age groups?

The objectives of this study were to evaluate the manubriosternal joint (MSJ) to estimate the minimum chronological age of complete fusion, and how changes in this joint influence age estimation. The study also focused on investigating the calcification patterns of the second costal cartilage (SCC), as they may be related to age. Between January and September 2020, individuals between 30 and 80 years of age, who underwent chest tomography at our institution, were listed by sex and divided into five groups according to age with intervals of 10 years. Twenty patients from each age group and sex were randomly selected, and 200 patients were evaluated. The relationship between age and changes in MSJ and SCC was evaluated. The incidence of complete fusion did not differ significantly between the 30 and 80 age groups. A significant difference was found between the age groups and MSJ degeneration (p < 0.001). The degree of MSJ degeneration and calcification in SCC significantly increased with age, but the range was wide. These values might be used to support traditionally accepted age-estimation methods but not as independent indicators of specific age ranges.

A safe area for sternal puncture in children: an MSCT study based on sternal development

PURPOSE

Multislice spiral CT (MSCT) was used to investigate the anatomical characteristics of sternal development, and to provide anatomical basis for sternal puncture in children.

METHODS

We retrospectively analyzed the thoracic MSCT data of 600 children who received thoracic MSCT from January to June 2020 with their age ranging from 1 month to 19 years. The distribution of sternal ossification centers and adjacent tissues and organs was observed. Subcutaneous soft tissue thickness and the distance between the skin and the posterior margin of the sternum were measured in the central areas of sternal manubrium and mesosternum (segments I and II), and the correlation between the two was calculated using linear correlation.

RESULTS

A total of 600 patients were enrolled, the mean age was 9.87 years and the standard deviation was 8.28 years. The sternal manubrium and ossification centers at the I and II segments of the mesosternum were visible in all cases (100%). There was no ossification in segment III of the mesosternum in 15 cases (2.5%), including 12 cases (80%) adjacent to the posterior pericardium and 7 cases (46.7%) of lung tissue. There were 274 cases (45.7%) of segment IV without ossification, including 204 cases (74.5%) of adjacent pericardium and 95 cases (32.8%) of lung tissue. The xiphoid process was not ossified in 258 cases (43%), including 190 cases (73.6%) adjacent to the pericardium and 97 cases (37.6%) adjacent to the lung tissue. Correspondingly, the thickness of subcutaneous soft tissue of the sternal manubrium and the central region of the I and II segments of the mesosternum had a low positive correlation with age (P < 0.001), the distance between the skin and the posterior margin of the sternum showed a moderate positive correlation with age (P < 0.001), and the distance between the skin and the posterior margin of the sternum showed a high positive correlation with the thickness of subcutaneous soft tissue (P < 0.001).

CONCLUSIONS

Nonossification of the sternal ossification center usually occurs below segment III of the mesosternum and is usually adjacent to heart and lung tissue. Pediatric sternal puncture should be performed at the sternal manubrium and the mesosternum of segments I and II. However, attention should be paid to the space between multiple ossification centers. The thickness of subcutaneous soft tissue is a critical factor that determines the depth of the puncture.

Frequency of sternal variations and anomalies in living individuals evaluated by MDCT

PURPOSE

The aim of this retrospective study was to present the frequency and MDCT appearances of sternal variations and anomalies, as well as to highlight their clinical significance.

METHODS

This retrospective study was carried out on 1150 patients, who underwent chest MDCT. Axial planes, multiplanar and curved-planar reconstructed images were studied. Age and sex distribution of the variations was evaluated.

RESULTS

Anatomical variations of the sternum were found in 74.1%. The most frequent variation was the double-ended xiphoid process (36.9%), followed by the single xiphoidal foramen (25.8%) and the sternal sclerotic band (12.8%). Other variations observed were: sternal notch (10.1%), xiphoidal ligament calcification (8.3%), sternal foramen (4.9%), complete manubriosternal fusion (4.1%) and sternoxiphoidal fusion (4.1%), triple-ended xiphoid process (3.7%), sternal cleft (1.5%), whereas the rest of the variations including sternoxiphoidal junction pseudoforamen, suprasternal bone, pseudocleft, suprasternal tubercle and absence of xiphoid process were in less than 1%. In our subjects, sternal and xiphoidal foramina were adjacent to: the pericardium (37.14%), the diaphragm (22.9%), the mediastinal fat (17.1%), the liver (11.4%), the lung (8.5%) and to the stomach (2.9%).

CONCLUSIONS

Sternal variations are frequent, asymptomatic, detected incidentally at cross-sectional imaging and may be confused with pathologic conditions. Radiologists should be familiar with these variations in order to discriminate them from pathologies and avoid complications during interventional procedures.

ADVANCES IN KNOWLEDGE

This study presents thoroughly the sternal variations' MDCT appearance, detected in a Greek population, correlates them with age and gender and discuss their clinical significance in detail.

High prevalence of sternal foramina in indigenous Bolivians compared to Midwest Americans and indigenous North Americans (sternal foramina in indigenous Bolivians)

The sternal foramen, usually an asymptomatic osteological defect, can lead to catastrophic consequences if not recognized prior to certain medical procedures. This study reports the prevalence of a sternal foramen in two South Amerindian populations compared with other published populations. We evaluated the presence of sternal foramina using thoracic computed tomography scans of 1334 (48% female) participants from two indigenous populations of Bolivia (n = 900 Tsimane, 434 Moseten). The prevalence of sternal foramina was compared to two U.S. populations of similar sex/age distribution (n = 572 Midwest Americans, 131 self-identified Native North Americans) via similar CT scans. A sternal foramen was significantly more common in the two Bolivian populations (prevalence ranging from 12.8 to 13.4%), compared to 4.4-5.1% in the two U.S. groups, consistent with prior estimates in studies from industrialized populations. Males had higher frequency of a sternal foramen compared to females in each of the four groups (OR = 1.904, 95% CI: 1.418-2.568, p < 0.001). Age was not associated with sternal foramen presence. These data show both a higher rate of sternal foramina in the South Amerindian populations versus comparator populations in North America and the highest rate of any studied living population. Although it is not possible to determine from our data the relative contribution of genetics versus early life or environmental causes to the higher rates of sternal foramen, we note that small prior studies have likewise demonstrated a higher prevalence in lower income countries. Further determination of the contributing factors warrants greater investigation and research.

Sternal human variability and population affinity: Frequency of discrete traits and their relationship with sex and age

Sternal morphological variations differ among populations and are influenced by the interaction between inheritance, development, and environment. There are currently no studies that include all variability from a morphogenesis approach following a homogeneous definition. The aims of this study were (a) to develop a standardized method for the anatomical study of the sternum; (b) to analyze the prevalence of the morphological variations and their relationship between sex and age; (c) to compare the results with other populations. The sterna of 155 skeletons from a Spanish population were studied. The age at the time of death was 17 to 97 years. We analyzed two metric and 22 sternal morphological variations described in the literature and designed an illustrated atlas. The atlas was validated using the intraclass correlation coefficient (ICC). A descriptive statistical analysis was conducted to measure the prevalence and relationship between sex and age. To analyze the interpopulation variability, we compared our results with those from other authors. The atlas with definitions and reference images improves the observation and detection of all morphological variations of the sternum (ICC = 0.90). The dependence between the morphological traits and sex was significant for the variations in the sternal angle, the number of esternebra, and the development of the xiphoid process. No significant differences were found between age group and morphological traits. The expression of the sternal morphological variation and sex are population-specific. The results will help standardize future studies and provide valuable information on the variability of the sternal morphological variation.

Honeycomb sterna: an unusual case of a developmental abnormality in the sternum

This report details an unusual case of a human sternal developmental abnormality of an anatomical specimen part of the skeletal collection curated by University College London, Anthropology Department skeletal collection. This rarely reported developmental abnormality is caused by the non-fusion of lateral ossification centres in the sternebrae, resulting in the mesosternum having a honeycomb-like appearance. Sternal defects are typically underreported in the clinical literature as many cases being asymptomatic that they are typically diagnosed incidentally, as such there is a dearth in our current understanding of the development and anatomical variants of the sternum. Although in recent years, large-scale CT studies have investigated the prevalence of sternal developmental abnormalities, these studies have not reported sternal defects similar to the individual presented in this report. While most sternal defects are clinically uneventful, the lack of awareness of these variants can result in misinterpretation of radiological and pathological findings as such an understanding of anatomical variants even when asymptomatic is vital.

Bifid Xiphoid Process: Case Report and Review

The xiphoid process is a bony process that comprises part of the sternum. This anatomical structure exhibits several morphological variations, which may complicate diagnostic examinations and invasive thoracic procedures. Variations include bifurcated or trifurcated, deflected, and curved processes. This report discusses a case of a bifid xiphoid process during cadaveric dissection and compares similar findings in the literature. The aim is to improve our knowledge of anatomical variations in an effort to reduce complications and improve patient care.

A Comprehensive Review of the Sternal Foramina and its Clinical Significance

A sternal foramen (SF), which arises from the incomplete fusion of the cartilaginous neonatal sternum, is a relatively common anatomical variation found in 2.5% to 13.8 % of all individuals. SFs are usually located at the lower third of the sternal body and their average diameter is 6.5 mm. An SF is subclinical; however, its close proximity to the thoracic organs, i.e., the heart and lungs, entails a risk of serious complications from blinded sternal interventions. Moreover, its presence can lead to misinterpretation of radiological and postmortem findings. The SF is ignored by many physicians and non-physician healthcare providers who must understand its clinical significance in order to optimize patient care. Our aim in this review is to highlight the potential clinical consequences for SF patients, discuss recommendations for performing sternal procedures safely when this anatomical variation is present, and preclude radiological and pathological misinterpretations so that patient care can be improved.