In forensic medicine, age estimation from the ossification of bones is of great importance. This is due to growing population, increasing immigration, and massive undocumented birth rate. Several studies have been published on this topic. These studies have mostly used traditional methods of anthropology and thorough examination of bones of the dead. Advanced methods involving X-ray and computed tomography scan have been used to produce better results. This is largely attributed to the high quality of images used. In this regard; studying the radiographs of medial clavicular epiphysis for estimation of age has proved to be useful.
Different ethnic groups show different growth patterns due to variation in their surrounding environments and genes. As for example, previous studies on medial clavicular epiphysis have shown different results among the Spanish population, German population, and others. For this reason, it is important to note the ossification stages of bones in different ethnic groups.
Studies involving the East Indian (Bengali) population using advanced methods have not been found up to this date with adequate sample size. Thus, we have attempted to determine age using such advanced technique. In our study, X-ray plates of medial clavicular epiphysis have been used to determine age in case of the East Indian (Bengali) population.
The present work has been conducted by the examiners of the Department of Forensic and State Medicine of Calcutta National Medical College, Kolkata. Ten months was the study period. The study was conducted on 200 patients (102 males and 98 females) brought for chest X-ray (PA view) examination at Calcutta National Medical College. Proper informed consent was taken from the patients or their next of kin. Ethical clearance was taken from the Ethics Committee of Calcutta National Medical College; no additional radiation was given to the study participants.
The cases taken were according to the inclusion criteria:
- Age between 10 and 26 years at the time of the X-ray examination (medico-legally significant age group)
- Good quality radiographs
- Stable hemodynamic status and normal chest radiographs of the individuals.
Exclusion of certain cases was based on the following criteria:
- Patients suffering from congenital, endocrine, structural, or other serious diseases
- Overlapping or unclear radiograph.
Medial clavicular ossification stage was determined by three observers under the supervision of the radiologist of the X-ray center. The ossification stages of epiphyseal cartilage of the medial side of the clavicle from the X-ray images were noted [Figure 1]. The degree of ossification was classified into five grades as follows:
- Grade 1: Invisible ossification center
- Grade 2: Visible ossification center without any ossification of epiphyseal cartilage
- Grade 3: Visible ossification center with partial ossification of epiphyseal cartilage
- Grade 4: Complete ossification of epiphyseal cartilage with epiphyseal scar
- Grade 5: Complete ossification of epiphyseal cartilage without epiphyseal scar.
Data analysis was performed using SPSS (Statistical Package for the Social Sciences) software (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, NY: IBM Corp.). Chi-square tests, analysis of variance (ANOVA), and post hoc tests were used in the study. P < 0.05 was considered statistically significant. Results are expressed in the form of tables, and similarities with other studies are discussed.
In this study, there were a total of 200 study participants, of which 102 were male and 98 were female. The minimum age among the study participants was 10 years and the maximum age was 26 years. The mean age for male patients was 19.54 years. In case of female patients, the mean age was 19.99 years.
Our study was conducted among patients brought for examination of the chest due to various medical reasons. Two hundred cases were selected randomly after considering the inclusion and exclusion criteria between 10 and 26 years of age. Cohen's kappa statistics showed good intraobserver and interobserver agreements.
On statistical analysis, we obtained the following results from the sample. The distribution of population was 35 cases in the 10–15 years' age group; 86 cases in the 16–21 years' age group and 79 cases in the 22–26 years' age group. Grading of ossification at the epiphyseal cartilage of medial clavicle was done among the 200 selected cases. On analysis, it was found that 16 cases were Stage 2, 54 cases were Stage 3, 78 cases were Stage 4, and 52 cases were Stage 5, as shown in Table 1. No variability of medial clavicular epiphyseal ossification was found between right and left clavicles. We also correlated the stages as per the grading of ossification at the epiphyseal cartilage of medial clavicle with the age groups in the population. As shown in Table 1, most of the cases in the age group of 22–26 years were Stage 5. We can also see that the Chi-square test value is significant (P < 0.001). From Table 2, we can see that the mean age for achieving Stage 3 is 17.50 years in males and 16.73 years in females. In case of Stage 4, it is 20.02 years in males and 20.13 years in females. Moreover, in case of Stage 5, it is 24.11 years in males and 24.61 years in case of females. The ANOVA test [Table 3] performed on the sample showed the significance value, P = 0.00 (P < 0.05). The post hoc test is demonstrated in Table 4 to allow the comparison between the different age groups. The mean difference is found to be significant below 0.05 level for all age groups. Graph of mean age versus ossification grade is shown in [Figure 2].
The grading of ossification at the epiphyseal cartilage of medial clavicle has rarely been explored as a tool for forensic purposes. In our study, we have tried to demonstrate the importance of this sign in forensic estimation of chronological age. This is the first study of its type in the Eastern Indian population. In our study, the degree of epiphyseal ossification of medial clavicle showed that the averaged ossification grades increased with increasing age between 10 and 26 years of age.
In forensic practice, the most crucial question from the medico-legal point of view is the determination of minimum age at which the ossification of epiphyseal cartilage of medial clavicle is completed. Previous radiological studies concur in establishing 22 years as the minimum age for the total fusion of that epiphysis. It can be seen from our study that the mean age for achievement of Stage 5 in both genders is 24 years. This is slightly different from the findings of the study done by Schmeling etal. (2004) which showed that the minimum age for achieving Stage 5 in both genders was 26 years. In our study, Stage 4 was achieved in both genders at 20 years. This is in contrast with the previous study which showed the achievement of Stage 4 in males at 21 years and in case of females at 20 years. These age thresholds show similarity to the anatomical studies done by Owings Webb and Myers Suchey and Ji etal. (1994). According to the study by Kreitner etal., radiology is more likely to detect ossification than naked-eye observation during autopsy. From our study, it is seen that the mean age for achieving Stage 3 is 17.50 years in males and 16.73 years in females. This can be significant from the point of view of declaring a person juvenile as per the various laws applicable.
However, conventional radiography of the clavicle is often plagued by overlapping shadows produced by structures of the mediastinum, the vertebrae, and the ribs. This results in inaccurate visualization of the medial epiphysis and thus cannot be used for staging the extent of maturation. Hence, other highly accurate methods studying bone ossifications and viscera are recommended for future researches.
We can conclude that plain chest radiography has a significant but limited role in forensic age estimation. The data of the present study supplement the existing database. It also facilitates advanced possibilities of diagnosis of 17 years or 24 years of age. This can be of importance in various cases of doubtful age in heinous crimes and unaccompanied minor refugees in cases of unlawful immigration. From previous studies, it has been seen that the reference values of a particular ethnic race are determined by the socioeconomic status of the population. If a reference value from a socioeconomically advanced population is applied to populations from a weaker socioeconomic background, then there will be underestimation of the calculated ages. It can lead to injustice being meted out to the person concerned. Hence, a study on ethnic regional population is very important.
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