Anthropometric evaluation of side, sex and age by radiological examination of the normal ankle joint among adult Egyptian population

Purpose – Sex and age estimation is important, particularly when information about the deceased is unavailable. There are limited radiological studies investigating side, sex and age differences in normal ankle morphometricparameters.Theauthors ’ goalwastoevaluatedifferentanklejointmorphometricmeasurements and document variations among Egyptians. Design/methodology/approach – A prospective study was conducted throughout 23 months on 203 (100 males and 103 females) adult Egyptians, aged between 20-69 years old, who were referred for a plain x-ray of bilateral normal ankle joints. Findings – Ankle parameters showed no statistical difference between both sides, except for tarsal width (TaW) which was significantly higher on right than left side (26.92 ± 2.66 vs 26.18 ± 2.65 mm). Males showed significantly higher morphometric values except for anteroposterior gap (APG) and talus height (TaH) which were significantly higher in females (2.29 ± 0.80 vs 1.80 ± 0.61 mm and 13.01 ± 1.68 vs 11.87 ± 1.91 mm, respectively).Therewas significantincrease intibialarc length, APG,distance oflevelofMTiThfromanterior limit of mortise, distance of level of MTiTh from vertex of mortise, sagittal distance between tibial and talar vertices and sagittal radius of trochlea tali arc in old age group compared to young one. A significant decrease in tibial width, malleolar width, TaW

Frequently, the skull, pelvis and long bones are damaged or absent, so the prediction of sex or age should be directed toward other parts of the skeleton.Nevertheless, the accuracy level of identification from other skeletal elements depends on their degree of difference (Abdel Moneim et al., 2008).For example, in previous studies, foot skeletal components have been used for sex assessment, such as metacarpal bones (Zanella & Brown, 2003), and calcaneus and talus (Introna, Di Vella, Ampobasso, & Dragone, 1997).However, the availability of knowledge about the geographical origin or the ethnic group of the victim for the anthropologist is important before sex and age determination (Abdel Moneim et al., 2008).Similarly, little data are available regarding the morphological variability of the human ankle regarding age and sexual dimorphism (Angthong et al., 2020).
The measurement methods used for ankle morphometry are widely varying (Khanasuk et al., 2011).Cadaveric specimens, radiographs, and computerized tomography images are mostly applied to obtain detailed ankle morphometric parameters (Han et al., 2019).
Therefore, the purpose of the current study was to document the morphometric parameters of the human ankle joint obtained by x-ray radiographs regarding side, sex and age-based differences among Egyptians.

Study design
A prospective study was conducted on 203 subjects who met the criteria, including 100 males and 103 females with ages ranging from 20-69 years old.These cases were referred to the Radiology Department of Suez Canal University Hospital from the Orthopedic and Physiotherapy Clinics to perform ankle joint plain x-ray radiographs in the period between January 2020 and December 2021.This study was approved by the Research Ethics Committee of the Faculty of Medicine, Suez Canal University (approval No. 5046#).In addition, informed consent from the enrolled subjects was obtained.Only Egyptian subjects whose parents and grandparents are Egyptians with normal ankle joints were included in this study, while patients with a history of ankle joint surgery, fracture, tumor, inflammation, deformation or congenital anomaly were excluded from the study.Furthermore, low-quality radiographs were not utilized in this study.

Plain x-ray procedures
Ankle radiographs were obtained by using a radiographic image unit (GE Healthcare, Chicago, IL) set to 60 kVp and 6.3 mA at a distance of 110 cm.In anteroposterior radiographs, AGJSR subjects stood with equal weight-bearing on both inverted feet, whereas in lateral views, subjects stood with equal weight-bearing on a support fixture and the cassette was held between both feet with the medial and lateral malleoli placed on each side of the cassette (Kwon et al., 2014).
While taking x-ray radiographs, a metal rod with a known actual length was placed beside the ankle joint to use it for calibration during the morphometric analysis of the radiographic images.To ensure accurate calibration, this metal rod was applied at an angle of 908 to the horizontal ground surface.
All measurements were performed using ImageJ® software (Wayne Rasband NIH, Bethesda, MA, USA) by only one well-trained investigator to reduce the inter-observer bias.This investigator carried out the study measurements three times with at least a one-month interval between each to ensure minimal intra-observer bias and high repeatability of the morphometric procedures.The mean of these three measurements of each parameter was recorded.

Morphometric parameters
Radiographs were displayed on a picture archiving and communication system software program to perform the morphometric analysis of the components of the ankle joint (Stagni, Leardini, Ensini, & Cappello, 2005;Yurttas et al., 2018) which are shown in Figure 1 and Table 1.

Evaluation of asymmetry
Percent directional asymmetry (%DA) was used for the assessment of the directional asymmetry in the tibial and talar measured parameters.It was calculated as follows: %DA Where (L) is the left-side measurement, while (R) is the right-side measurement.The percent above zero means that there are right-side asymmetries, whereas the percent below zero means that there are left-side asymmetries.

Anthropometry radiological ankle Egyptian
A quantitative measure of directional asymmetry in each parameter was calculated by the percent absolute asymmetries (%AAs) to evaluate the degree of asymmetry, irrespective of its directionality, as follows: Where (Max) is the maximum measurement, while (Min) is the minimum measurement (Auerbach & Ruff, 2006).

Statistical analysis
Data analysis was performed using Statistical Package for Social Sciences (SPSS) software version 27.0 for Windows (IBM Corp., Armonk, NY, USA).Data were expressed as means and standard deviations (SD), in addition to the maximal and minimal values.A paired sample Student's t-test was used to compare the means of morphometric values according to side variability.On the other hand, to test the sexual dimorphism, an unpaired t-test was performed.One-way analysis of variance (ANOVA) with Tukey post-hoc test was used to test  Regarding the %DAs and %AAs, their values were tested for normality using the Shapiro-Wilk test, which demonstrated the non-normal (non-parametric) distribution of their data.So, we evaluated the significance of the %DAs and %AAs using the Mann-Whitney U-test which is the non-parametric equivalent of the two-sample t-test.
Pearson's correlation coefficient was performed to evaluate the relations between different study variables.The difference between the data was considered significant when the twotailed p value was ≤0.05.The intraclass correlation coefficient (ICC) was used to assess rating reliability by comparing the variability of the three values of each parameter recorded by the same investigator.ICC values were interpreted as follows: poor reliability <0.50; moderate reliability: 0.50-0.75;good reliability: 0.75-0.90and excellent reliability >0.90 (Koo & Li, 2016).

Results
The numbers of male and female subjects according to the age groups were expressed in Table 2.The ICC values of all parameters ranged from 0.920-0.970,indicating excellent intraobserver reliability of all recorded measurements (Table 3).According to the side of the ankle joints, only TaW of the right side was significantly higher than the left (26.92 ± 2.66 vs 26.18 ± 2.65 mm) (p 5 0.005).On the contrary, there was no statistical difference between other tibial or talar morphometric parameters on both sides of the ankle joints (Tables 4  and 5).
The evaluation of asymmetry revealed that there were right-sided asymmetries in all parameters except for TiAL, SRTi and TaAL in males and for TiAL, SRTi, TaAL and Taw in females where there were left-sided asymmetries (Tables 6 and 7).However according to the %AA assessment, only APG and TiW exhibited a significant asymmetrical directional bias comparing the males and females (p 5 0.042 and 0.048, respectively) (Tables 8 and 9).

Anthropometry radiological ankle Egyptian
When age is considered, the values of TiAL, APG, APA, MDA, MDV, SDTaTi and SRTa were significantly higher in subjects aged between 60-69 years as compared to those aged between 20-29 years, while TiW, MalW, TaW and TaH were significantly lower in subjects aged between 60-69 years when compared to those aged between 20-29 years.Whereas there was no statistically significant difference between these two age groups according to MTiTh, SRTi and TaAL values (Figure 3) (Tables 12-15).
According to the correlation among different study morphometric parameters, there were moderately significant positive correlations between TiW and Taw values (n 5 406, r 5 0.654, p < 0.001), and between APA and MDA values (n 5 406, r 5 0.615, p < 0.001).On the other hand, the correlations between other parameters were weak (Table 16).

Discussion
Part of forensic investigations may be implicated in identifying a decedent.Such identification is sometimes difficult, particularly when the human remains of the victim are fragmented, decomposed or mutilated (Rich, Dean, & Cheung, 2003).
Due to their protected nature in footwear, the feet and ankles usually escape the effects of trauma other than the rest of the body.Additionally, footwear not only slows down the process of disarticulation but also helps in the retention and preservation of foot and ankle bones.Furthermore, footwear adds a degree of protection from taphonomic alteration, e.g.animal scavenging, thus preserving the integrity of the pedal skeleton (Davies, Hackman, & Black, 2014).
Despite the use of the ankle joint in forensic investigations, which has been previously involved in medical and forensic literature (Steele et al., 1976;Singh et al., 1975;Rich, 2000;Rich et al., 2002), only a few studies have investigated the geometrical measurements of the ankle joint, and the common techniques for these measurements were plain x-ray, CT scan and MRI (Khanasuk et al., 2011).

AGJSR
As previously reported by Stagni et al. (2005) in Italy, all measured ankle morphometric values were higher than our reported results.Also, according to Kwon et al. (2014), all ankle parameters in the Korean population were higher than our results except for MTiTh (39.3 mm), TaAL (35.3 mm) and TaH (10.5 mm) which were lower than the values of the current study (40.9, 37.4 and 12.5 mm, respectively).In contrast, ankle joint measurements were lower than our ones with a Thai study conducted by Khanasuk et al. (2011), except for TiW (29.3 mm) and TaW (28.0 mm) which were higher than the results of the present study (28.3 and 26.6 mm, respectively).Kuo et al. (2014) in Taiwan concluded that ankle measurements are higher than our results regarding APG (3.6 vs 2.1 mm), APA (7.4 vs 3.68), MTiTh (42.0 vs 40.9 mm), MDA (11.4 vs 10.9 mm), MalW (63.1 vs 59.3 mm) and SDTaTi (4.5 vs 2.4 mm), while lower for TiAL (28.4 vs 28.9 mm) and TaH (11.9 vs 12.5 mm) values.
In accordance with our results, an American study by Hayes et al. (2006) reported that the mean SRTa was 20.7 mm which is slightly lower than that of the present study (21.1 mm ± 1.3 mm) (Table 17).In another study performed by Fessy, Carret, and B ejui (1997) in France, TiAL and TaAL were slightly higher than our results (30.8 vs 28.9 and 38.5 vs 37.4 mm, respectively).
The presence of bilateral asymmetry is considered normal in the human body.This may be attributable to both genetic and environmental factors (Krishan & Kanchan, 2016) Relation among the male tibial parameters according to the age groups AGJSR addition, the additional stress and strain on the dominant side of the body could also increase the incidence of this asymmetry (Gutnik et al., 2015).
A previous study conducted by Islam et al. (2014) using CT scan images for assessment concluded that there are small percent differences between the morphometric parameters of the left and right talus bones, supporting the fact that the tali of both sides are geometrically symmetrical based on the measurement of talus bone surface area and volume.The same results, but based on gross cadaveric assessment, were previously reported by Angthong et al. (2020) who reported that there are no statistical differences between left and right tali morphometric values, also according to both surface area and volume; however, they found that the talar dome height, middle trochlear width and posterior trochlear width of the right side were significantly higher than those of the left.In the present study, tali on both sides were symmetrical except for TaW of the right side which, was higher than the left (26.92 vs 26.18 mm).On the other hand, no statistical difference was found in this study between all other morphometric parameters of the left and right ankle joints.
Starting from the age of puberty, sex differences become apparent in bone growth.So, men develop greater bone size and higher bone mass compared to women.Recent findings attributed to the traditional concept of sex hormones are the chief regulators of this sexual dimorphism of the skeleton (Callewaert, Sinnesael, Gielen, Boonen, & Vanderschueren, 2010).
In the current study, MTiTh, MDV, TiW, MalW, SRTi, TaAL, TaW, SDTaTi and SRTa were significantly higher in males, while only APG and TaH were higher in females.According to APG, these results are in agreement with the findings of an Italian study by Stagni et al. (2005) who found that only APG and APA were significantly higher in females than males (2.7 vs 2.6 mm and 5.5 vs 4.78, respectively).Furthermore, in accordance with our results, higher values of SRTa, MTiTh, TiW, MalW and TaW in male subjects were recorded by Khanasuk et al. (2011) in Thailand.Kuo et al. (2014) in Taiwan and Uzuner et al. (2018) in Turkey found that MalW values were also higher in males.In contrast, both Khanasuk et al. (2011) and Kuo et al. (2014)  TiAL values are similar in both sexes, while the current study showed no statistical difference between male and female values according to TiAL (Table 17).As noted, the wide variability of values of ankle joint parameters among various studies could be due to different methods of evaluation.
Advances in medicine promoted increased life spans that led to the increased development of extensive lower extremity alteration due to significant musculoskeletal system changes that occur with aging, especially in post-menopausal women.For example, with age, bones lose their strength and rigidity; in addition, they become more brittle.Furthermore, joints and surrounding soft tissue become less flexible and weaker (Lee & Mulder, 2009).
In this study, TiAL, APG, APA, MDA, MDV, SDTaTi and SRTa were significantly higher in old age as compared to subjects aged 20-29 years, and significantly higher TiW, MalW, TaW and TaH values were noted in the subjects aged 20-29 years compared to those aged 60-69 years, indicating that ankle joint measurements are highly affected by age.
In addition to different methods of evaluation, the different number of involved subjects or different enrolled populations according to their ethnicity, age and sex could be the cause of the variability of the results of various studies.

Conclusion
The findings of this study among Egyptians recorded valuable details of morphometric ankle parameters that may be helpful during the identification of the side, sex and age in unknown subjects, especially when other more reliable body regions for this identification are lost or damaged.

Figure 1 .
Figure 1.Radiographs of the ankle joint showing the measured morphometric parameters

(
A) Lateral view (sagittal projection) parameters 1 Tibial arc length (TiAL) (mm) Distance between the most anterior (A) and the most posterior (B) points of the arc of the tibial mortise 2 Sagittal radius of the tibial mortise (SRTi) (mm) Radius of the circle fitting the tibial mortise profile 3 Antero-posterior gap (APG) (mm) Distance between the points (A) and (B) along the longitudinal axis of the tibia 4 Antero-posterior inclination angle of the tibial mortise (APA) (degrees) Inclination angle between the A-B connecting line and the tibial antero-posterior axis 5 Maximal tibial thickness (MTiTh) (mm) Distance between the most tibial anterior point (C) and the corresponding posterior point (D) 6 Distance of level of MTiTh from the anterior limit of the mortise (MDA) (mm) Longitudinal distance between (A) and (C) points along the tibia 7 Distance of level of MTiTh from the vertex of the mortise (MDV) (mm) Longitudinal distance between the vertex of tibial mortise (V1) and the point (C) 8 Trochlea tali length (TaAL) (mm) Length of the line connecting the most anterior (E) and the most posterior (F) points of the trochlea tali sagittal arc 9 Sagittal radius of the trochlea tali arc (SRTa) (mm) Radius of the circle fitting the trochlea tali arc points 10 Talus height (TaH) (mm) Length of the longitudinal line connecting the vertex of trochlea tali (V2) and the line connecting the most anterior (E) and the most posterior (F) points of the trochlea tali sagittal arc 11 Sagittal distance between tibial and talar vertices (SDTaTi) (mm) Distance between the vertex of the tibial mortise (V1) and trochlea tali vertex (V2) (B) Anteroposterior view (frontal projection) parameters 1 Tibial width (TiW) (mm) Length of the internal line fitting between the two malleoli (between the G and H points) 2 Malleolar width (MalW) (mm) Length of the line connecting the most medial point of the medial malleolus (K) and the most lateral point of the lateral malleolus (J) 3 Tarsal width (TaW) (mm) Length of the line along the top of talar articular surface extending between the most medial (M) and the most lateral points (L) of the talar articular profile Source(s): Figure 2. Radiographs of ankle joints of adult male and female aged 35 years old showing a comparison between their morphometric values Figure 3. Radiographs of ankle joints showing a comparison between two males of 28 and 68 years old according to their morphometric values Figure 4. Scatter plots showing the correlations between age and the different anthropometric parameters Note(s): Abbreviations: M, male; F, female; T, total.All measurement parameters are by mm except for APA id by degrees Source(s):

Table by authors
The intra-observer reliability was evaluated using the intraclass correlation coefficient (ICC) Source(s): Table by authors Values are presented as means, SD, minimum (Min) and maximum (Max).Statistical analysis was performed by paired student's t-test Source(s): Table by authors Table 4. Values are presented as means, SD, minimum (Min) and maximum (Max).Statistical analysis was performed by paired student's t-test Source(s): Table by authors Table 5.Values are presented as means and SD.Statistical analysis was performed by Mann-Whitney U-test Source(s): Table by authors Values are presented as means and SD.Statistical analysis was performed by Mann-Whitney U-test Source(s): Table by authors Values are presented as means and SD.Statistical analysis was performed by Mann-Whitney U-test Source(s): Table by authors Values are presented as means and SD.Statistical analysis was performed by Mann-Whitney U-test Source(s): Table by authors Values are presented as means, SD, minimum (Min) and maximum (Max).Statistical analysis was performed by unpaired student's t-test Source(s): Table by authors Table 11.