Radiological Evaluation of Sternal Fusion Pattern Including Manubriosternal and Xiphisternal Joints for Age and Sex Determination Using Computed Tomography of the Chest

Accurate estimation of age and sex from human skeletal remains is a cornerstone of forensic anthropology and medicolegal investigations. Traditionally, the pelvis, skull, and long bones have been primary skeletal markers due to their pronounced sexual dimorphism and known developmental timelines. However, in cases involving fragmentation, decomposition, or thermal damage—such as mass disasters or criminal cases—these bones may not be preserved. In such contexts, the sternum emerges as a valuable alternative for forensic identification due to its central location, predictable fusion patterns, and protection within the rib cage structure [1,2]. The sternum, or breastbone, is a flat bone situated in the midline of the anterior thoracic wall. It comprises three distinct components—the manubrium, body (gladiolus), and xiphoid process—that develop from separate ossification centers and gradually fuse over the human lifespan [3]. This biological characteristic allows radiologists and forensic anthropologists to correlate the fusion status of the manubriosternal and xiphisternal joints with chronological age, particularly in adult populations where other skeletal indicators are less informative [4,5]. Recent advancements in multidetector computed tomography (MDCT) and 3D imaging techniques have enabled high-resolution visualization of sternal morphology and ossification patterns. CT-based analysis offers numerous advantages over traditional radiography, including higher precision, reduced inter-observer variability, and the ability to reconstruct detailed anatomical models without invasive procedures [6,7]. The ability to perform non-invasive, reproducible morphometric measurements has made CT imaging a preferred method for forensic evaluations of the sternum. Moreover, the sternum exhibits measurable sexual dimorphism. Males typically have longer and wider sterna, whereas females present shorter and narrower configurations [8]. Morphometric parameters such as total sternal length, manubrium width, and the sternal index have been shown to achieve high accuracy (up to 90%) in sex estimation when applied through discriminant function analysis [9]. However, these measurements often vary significantly across different ethnicities, necessitating the development of population-specific reference data for forensic application [10]. In the Indian context, few studies have explored the radiological assessment of sternal features for forensic purposes. Given the genetic, environmental, and lifestyle diversity in the Indian population, establishing localized CT-based standards is essential to improve the accuracy of forensic identification. This study aims to evaluate the sternal fusion patterns and morphometric differences using CT imaging and assess their forensic applicability in age and sex estimation among adults in a North Indian population.

METHODOLOGY

2.1 Study Design

This research was conducted using a descriptive cross-sectional design, analyzing retrospective CT scan data to evaluate the fusion status and morphometric parameters of the sternum. The study employed a quantitative observational approach, enabling objective measurement and statistical correlation of anatomical features with demographic variables.

2.2 Study Setting

The study was carried out in the Radiology Department of SCPM Hospital and Medical College, Gonda, Uttar Pradesh, India. CT images were retrieved from the hospital’s Picture Archiving and Communication System (PACS), which stores digital radiological data, including chest CT scans from patients across various age groups.

2.3 Sample Selection

2.3.1 Target Population

Adult individuals aged between 18 and 70 years who underwent thoracic CT imaging for diagnostic purposes unrelated to trauma or musculoskeletal disorders.

2.3.2 Sampling Technique

A purposive sampling method was used to select CT scans based on inclusion and exclusion criteria.

2.3.3 Sample Size

The final sample included 100 individuals, comprising:

• 50 males
• 50 females

The sample size was determined based on feasibility, availability of suitable imaging records, and time constraints.

2.4 Inclusion and Exclusion Criteria

Inclusion Criteria

• Adults aged 18–70 years
• Normal sternal morphology on CT scan
• High-quality CT images displaying the entire sternum
• No prior chest surgery or sternal trauma

Exclusion Criteria

• Congenital anomalies or deformities of the sternum
• Pathological bone conditions (e.g., osteoporosis, osteomyelitis)
• Endocrine or metabolic disorders affecting bone development
• Incomplete or poor-quality CT images

2.5 Imaging Modality and Tools

• Imaging modality: Multidetector Computed Tomography (MDCT) chest scans
• Image analysis software: RadiAnt DICOM Viewer
• Data management tools: Microsoft Excel and SPSS Version 25.0

2.6 Measurement Parameters

The following morphometric and fusion parameters of the sternum were recorded:

1. Total sternal length (from suprasternal notch to tip of xiphoid process)
2. Manubrium length and body length
3. Sternal index: (Manubrium length / Body length) × 100
4. Fusion status of:
   • Manubriosternal joint
   • Xiphisternal joint

Fusion status was graded as:

• Grade 1: Unfused
• Grade 2: Partially fused
• Grade 3: Completely fused

2.7 Reliability and Validity

• Content validity was ensured by expert consultation with senior radiologists and anatomists.
• Intra-observer reliability: 20 randomly selected scans were re-evaluated after one week.
• Inter-observer reliability: Another radiologist independently assessed 20 scans.
• Statistical agreement: Measured using Intraclass Correlation Coefficient (ICC) and Kappa statistics for categorical variables.

2.8 Data Collection Procedure

1. CT images meeting inclusion criteria were retrieved from PACS.
2. Each scan was anonymized and assigned a unique study code.
3. Sternal morphometric and fusion parameters were measured using the DICOM viewer.
4. Data were entered into Excel and exported to SPSS for statistical analysis.

2.9 Statistical Analysis

• Descriptive statistics: Means, standard deviations, frequencies.
• Inferential statistics:
  • Chi-square test (χ²): To examine associations between fusion status and age/sex.
  • Independent sample t-test: To compare sternal lengths between sexes.
  • Pearson’s correlation coefficient: To assess relationships between sternal measurements and age.

A p-value < 0.05 was considered statistically significant.

RESULTS

A total of 100 CT scans (50 males and 50 females) were analyzed to evaluate sternal fusion patterns and morphometric differences for the purposes of forensic age and sex estimation.

3.1 Demographic Distribution

The majority of participants (33%) were in the 31–45-year age group. The 46–60 group followed closely at 30%. This distribution supports the evaluation of age-related fusion patterns across early, middle, and late adulthood. Slight over-representation of females in the youngest group may influence early fusion trends.

3.2 Fusion Status of Manubriosternal and Xiphisternal Joints