Science and Justice 55 (2015) 139–144
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Examination of ossification of the distal radial epiphysis using magnetic resonance imaging. New insights for age estimation in young footballers in FIFA tournaments S. Schmidt a, V. Vieth b, M. Timme a, J. Dvorak c,d, A. Schmeling a,⁎ a
Institute of Legal Medicine, University Hospital Münster, Röntgenstraße 23, D-48149 Münster, Germany Institute of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, D-48149 Münster, Germany c Department of Neurology, Schultheiss Clinic, Lengghalde 2, CH-8008 Zurich, Switzerland d FIFA Medical Assessment and Research Centre (F-MARC), Schultheiss Clinic, Lengghalde 2, CH-8008 Zurich, Switzerland b
a r t i c l e
i n f o
Article history: Received 7 August 2014 Received in revised form 26 November 2014 Accepted 10 December 2014 Keywords: forensic age diagnosis skeletal age hand radius MRI
a b s t r a c t Alongside a variety of clinical and forensic issues, age determination in living persons also plays a decisive role in the field of professional sport. Only methods of determining skeletal age which do not expose individuals to ionizing radiation are suitable for this purpose. The present study examines whether MRI diagnosis of the distal radial epiphysis can be utilised to monitor internationally relevant age limits in professional football. The wrist area of 152 male footballers aged 18 to 22 years belonging to regional clubs was prospectively examined using MRI. The ossification stage of the distal radial epiphysis was subsequently determined on the basis of established criteria used in determining the maturity of the medial clavicular epiphysis. For the first time, we ascertained evidence of an increase in the prevalence of the phenomenon of threefold linear stratification (hypointense line, hyperintense line, and hypointense line) in the representation of the fused epiphyseal plate of the radius using magnetic resonance imaging with increasing chronological age. Within our study population, test persons with an ossified epiphyseal plate without any verifiable epiphyseal scar were not represented. The presumably high minimum age of entry into this final stage of development (N 22 years) must be verified in the course of further studies. According to the results of the present study, the fused epiphyseal plate of the distal radius provides potential maturation criteria which appear suitable for reliable monitoring of all relevant age limits in international football with the aid of magnetic resonance imaging. © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.
1. Introduction Over the past 20 years, scientific insights gained in the field of age diagnosis in living persons have been mainly inspired in an almost unprecedented manner by the specific requirements of practical forensic work [1–6]. However, application of the results of this development is not restricted to conventional medical and legal contexts. Thus, the methods used to clarify the stated age of living individuals are also gaining increasing significance in the organisation of elite sporting competitions [7]. In this context, it is the primary responsibility of international sporting federations to guarantee by means of age divisions that all participants enjoy the equal opportunities required for ethical reasons. At the same time, any physical and/or psychological and social strain on sportspeople not in line with their age is to be avoided as a significant source of self-endangerment in relation to health. Finally, with regard to contact and collision sports, in particular, it is also important ⁎ Corresponding author. Tel.: + 49 251 83 55 156; fax: + 49 251 83 55 158. E-mail address: [email protected] (A. Schmeling).
to protect physically weaker team members from injuries caused by older players. Tournaments organised by the Fédération Internationale de Football Association (FIFA) as an international football governing body include the U-17 and U-20 World Cups. These are both staged between the best junior male national teams in uneven years and the best junior female national teams in even years. In these competitions, all male and female footballers are entitled to play if they reach the relevant age limits on 1 January of the year of the Cup Final at the earliest. More specifically, therefore, participation following completion of the 18th or 21st year of life, respectively, is excluded. The age range between 15 and 23 years in both sexes is highly relevant to international youth football for the various championship tournaments organised by the continental federations subordinate to FIFA. The identity of all participants is monitored by the organisers in the run-up to each football tournament on the basis of personal documents, such as ID cards, passports, birth certificates, etc. On a number of occasions in the past, suspicions have arisen that the age stated for individual junior players was incorrectly low [7–9]. A certain proportion of
http://dx.doi.org/10.1016/j.scijus.2014.12.003 1355-0306/© 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.
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cases may be due to delayed, sometimes unsupported, in some places even completely lacking, registration of births, such as is the case especially in various countries of origin for geographic and cultural reasons. However, cases of criminally motivated misdeclarations in the sense of so-called “age doping” can also scarcely be ignored. By this means, the chances of an individual player to be signed by a renowned football club may possibly be increased [10]. In general, however, the illicit participation of older players also wrongfully enhances the prospects of a team victory in age-restricted football tournaments. In recent times, questions relative to the general meaningfulness and the ideal means of monitoring age in professional youth football have repeatedly been the subject of scientific debate [11,12]. In view of the fact that the genetically determined maturation sequences of individual osseous elements occur within a certain range of variation with a comparatively high level of regularity [13–16], skeletal maturation can still be considered the most significant indicator of biological age. However, the X-ray examinations required for the majority of established methods of determining skeletal age are not legally justified in the field of sport, and in the judgment of the International Olympic Committee (IOC), cannot be advocated according to sports ethics [7]. For this reason, future research efforts in this area must be mainly focussed on further establishing examination methods for purposes of skeletal age diagnosis which do not expose the individual to ionizing radiation. So far, a number of general approaches to resolving this problem have been highlighted [17–25,25a,25b,25c]. Initial trendsetting attempts have been undertaken to routinely apply such methods using magnetic resonance imaging to ascertain the ossification stage of the distal radial epiphysis to determine the age of professional footballers [9]. The objective of the present pilot study is to examine whether MRI diagnosis of the distal radial epiphysis can be utilised to monitor internationally relevant age limits in professional football. 2. Test persons and methods The tests encompassed the prospective evaluation of magnetic resonance imaging scans of the area of the left wrist in a total of 152 German male volunteers aged between 18 and 22 years. All details of age were monitored on the basis of a tendered official identification document. The 18-, 19-, and 21-year-old age groups each comprised 30 persons, the 20- and 22-year-old age groups 31 persons. The study population was comprised of amateur footballers who were enrolled at the time of the study as active players in a club registered with the German Football Federation. Growth disorders were ruled out when collecting the medical history of the test persons. All the MRI examinations on which the study is based were performed in the months from February to June 2011 at the Institute of Clinical Radiology of the University Hospital Münster (Germany). The project was supported by a positive vote of the ethics commission responsible; this vote was based on a comprehensive explanation of risks and the written declaration of consent given by all test persons. The imaging diagnostics were performed on a 3.0 T scanner (Achieva, Philips Medical Systems, Netherlands) using a surface coil (Sense Flex M, Philips Medical Systems, Netherlands). Based on clinical radiological methods of hand age diagnosis, a T1-weighted turbo spin echo (T1-TSE) sequence in coronal sectional orientation (TR: 635 ms; TE: 11 ms; FA: 90°; NSA: 3; FoV: 100 × 100 mm; slice thickness: 1.5 mm; scan time: 6.0 min; measured matrix: 248 × 180 [m × p]; measured voxel size: 0.4 × 0.5 × 1.5 mm; recon voxel size: 0.2 × 0.19 × 1.5 mm) was used for image acquisition so as to achieve a scan of as long a section of the distal radial epiphysis as possible. Only scans of the left hand were included in the investigation, as significant traumatic changes to the right hand are more prevalent in the population as a whole. Potential differences between the sides in the degree of maturation do not represent a relevant source of error in determining the age of the hand skeleton [25d].
A ViewForum Workstation (Philips Medical Systems, Netherlands) with a diagnostic monitor was available for masked assessment of the MR scans. To determine the ossification stage of the distal radial epiphysis, a combination of the classification systems proposed by Schmeling et al. [26] and by Kellinghaus et al. [27] was used (Table 1). When determining the ossification stage, the entire image sequence generated for each test person was evaluated. When determining stages 2 and 3 (including substages), the slice with the most advanced degree of ossification was selected in each case. Stage 4 was determined whenever the growth plate was fully ossified in all the slices and an epiphyseal scar or the remains of one were visible in at least one slice. Stage 5 was determined whenever the growth plate was fully ossified in all the slices and no traces of any epiphyseal scar were visible in any of the slices. All the images were first evaluated by an examiner (forensic physician) with experience in skeletal age determination. This first examiner evaluated 30 cases for a second time after a time lapse of three months. In the case of this partial group, a further evaluation was performed by a second examiner (forensic physician) who also had wide experience in skeletal age determination. All evaluations were performed without knowledge of the age and sex of the individuals examined. We used SPSS 16.0.1 (IBM SPSS Statistics) software for the statistical evaluation of the data. A variety of statistical measures (minimum age, maximum age, mean value with standard deviation, and median with lower and upper quartiles) were calculated to describe the individual ossification stages. The kappa coefficients were calculated to determine intra- and interobserver agreement.
3. Results Figs. 1 to 5 illustrate the characteristic MRI findings of ossification stages IIc, IIIa, IIIb, IIIc, and IV of the distal radial epiphysis which were detected in the study population. Ossification stages I, IIa, IIb, and V were not found amongst our test persons. In all cases included in the study, it was possible to determine the ossification stage of the distal radial epiphysis using magnetic resonance imaging. For intraobserver agreement, a kappa coefficient of 0.94 was calculated. According to the verbal ratings proposed by Altman [28], this corresponds to a very good level of agreement. For interobserver agreement, a kappa coefficient of 0.88 was calculated. This value also corresponds to a very good level of agreement. Ossification stages IIc and IIIa were established exclusively in the 18-year-old age group, whilst ossification stage IIIb was found only in the 18- and 19-year-old age groups. Within the studied age spectrum as a whole, ossification stage IIIc was ascertained with decreasing frequency as chronological age increased, whilst ossification stage IV became increasingly frequent. Table 1 Stage classification of ossification of the distal radial epiphysis modified according to Schmeling et al. [26] and Kellinghaus et al. [27]. Stage Description I IIa IIb IIc IIIa IIIb IIIc IV V
The epiphysis has not yet ossified The length of the ossified epiphysis is one-third or less compared to the width of the metaphyseal ending The length of the ossified epiphysis is between one-third and two-thirds compared to the width of the metaphyseal ending The length of the ossified epiphysis is over two-thirds compared to the width of the metaphyseal ending Epiphyseal–metaphyseal fusion completes one-third or less of the epiphyseal plate Epiphyseal–metaphyseal fusion completes between one-third and two-thirds of the epiphyseal plate Epiphyseal–metaphyseal fusion completes over two-thirds of the epiphyseal plate The epiphyseal plate is fully ossified and the epiphyseal scar is visible The epiphyseal plate is fully ossified and the epiphyseal scar is no longer visible
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Fig. 1. MRI sectional image of an ossification stage IIc of the distal radial epiphysis. The lengthwise epiphyseal measurement is over two-thirds compared to the widthwise measurement of the metaphyseal ending.
Fig. 3. MRI sectional image of an ossification stage IIIb of the distal radial epiphysis. The epiphyseal–metaphyseal fusion (arrows) completes over one-third but less than twothirds of the former gap between epiphysis and metaphysis.
Table 3 displays the measures of location and dispersion relating to the statistical description of the ossification stages determined. The measures demonstrate an increase in the mean values and medians of the chronological age of the test persons with an increase in the ossification stage of the distal radial epiphysis. Twenty-five of the 82 cases studied which were classified as ossification stage IIIc (30.5%) each displayed a threefold stratification (hypointense line, hyperintense line, hypointense line) within the fused parts of the epiphyseal plate which has not previously been described. Thirty-one of the 64 cases studied which were classed as ossification stage IV (48.4%) displayed the same findings. In the diagram broken down by increasing chronological age (Fig. 6), it becomes clear that the frequency with which this morphological constellation can be attested in ossification stage IIIc tends to decrease, whereas in ossification stage IV, it increases until completion of the 22nd year of life.
Based on established radiological methods, the potentialities of determining age in the sport of football by determining hand skeleton
maturity by means of magnetic resonance imaging, without exposure to ionizing radiation, were published as early as 2007 [9]. For this purpose, the authors had examined a total of 496 healthy male football players in the age groups from 14 to 19 years, with reliable dates of birth, from a variety of national and regional federations in Switzerland, Malaysia, Algeria, and Argentina. Using the results obtained, they compiled a classification system based on the stages of the process of ossification of the distal radial epiphysis (Table 2; hereafter ossification stages according to D). For this grading, a significant correlation between the ossification stage and the chronological age of the individual as well a high level of intra- and interobserver agreement were established. The practical applicability of the method developed by Dvorak et al. was tested when ages were verified at four U-17 football tournaments by the authors themselves [29]. The analysis included 189 players who were selected as random samples from the 16 teams participating at each of the following: the FIFA U-17 World Cup in Finland (2003), the AFC U-17 Championship in Japan (2004), the FIFA U-17 World Cup in Peru (2005), and the AFC U-17 Championship in Singapore (2006). Compared with the previous study, it became apparent that U-17
Fig. 2. MRI sectional image of an ossification stage IIIa of the distal radial epiphysis. The epiphyseal–metaphyseal fusion (arrow) completes less than one-third of the former gap between epiphysis and metaphysis.
Fig. 4. MRI sectional image of an ossification stage IIIc of the distal radial epiphysis. The epiphyseal–metaphyseal fusion completes over two-thirds of the former gap between epiphysis and metaphysis.
4. Discussion
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S. Schmidt et al. / Science and Justice 55 (2015) 139–144 Table 3 Statistical measures (in years).
Fig. 5. MRI sectional Image of an ossification stage IV of the distal radial epiphysis. The epiphyseal cartilage is fully ossified. Note the partial threefold stratification in the area of the former epiphyseal plate (arrow).
professional footballers displayed a higher skeletal age on average than was the case in players of the corresponding age in the reference population. In the view of the authors, this fact suggests the initial suspicion that the ages given in the official documents of the U-17 players examined were not correct in every case. The implication that some footballers gained advantages for themselves and/or their teams in U-17 tournaments by giving incorrect ages became the object of extensive criticism of the study by Dvorak et al. [12]. The key point in the counterargument is the statement that a tendency towards acceleration in skeletal age can be observed in sub-elite and elite groups of football players, particularly after the 13th to 14th year of life [30,31]. The discrepancies ascertained among professional teams were seen as a consequence of a selection of particularly high-powered early developers from the overall pool of all football players developing in accordance with their age [31]. However, the extent to which the ages given by the participants in the study by Malina et al. were reliable remains unclear. The possibility of a selective influence on the skeletal age distribution of professional footballers was also discussed by Dvorak et al. [29]. In spite of this, the study presented some particularly unusual results which could not easily be reconciled with such an assumption. Thus, there was no significant correlation between the ossification stages of the distal radial epiphysis determined by magnetic resonance imaging on the one hand, and the chronological age groups on the other, in the study cohort of professional players as compared with the reference population of male footballers. Moreover, in the 14-year-old age group, three out of eight sportspersons displayed an ossification stage VI (D), whilst two manifested an ossification stage V (D). By contrast, in the corresponding age group in the reference population, none of the ossification stages IV (D), V (D), or VI (D) were ascertained [9]. A selection effect would give reason to expect that the proportion of Table 2 Stage classification of ossification of the distal radial epiphysis using magnetic resonance imaging according to Dvorak et al. [9]. Stage
Description
I II III IV V VI
Completely unfused Early fusion: minimal hyperintensity within the physis Trabecular fusion of b50% of the radial cross-sectional area Trabecular fusion of N50% of the radial cross-sectional area Residual physis, b5 mm on any one section Completely fused
Stage
Number of cases
Minimum
Maximum
Mean value; standard deviation
Lower quartile; median; upper quartile
IIc IIIa IIIb IIIc IV
1 2 3 82 64
18.6 18.1 18.6 18.1 18.3
18.6 18.8 19.7 22.8 22.9
– 18.4 ± 0.4 19.2 ± 0.6 20.3 ± 1.4 21.1 ± 1.3
– 18.1; 18.4; – 18.6; 19.4; – 19.0; 20.2; 21.5 20.3; 21.1; 22.3
higher ossification stages would increase within an age group. This hypothesis, however, does not explain why these stages occur several years earlier in the selected sample than in the normal population. Finally, following the commencement of random age checks by Dvorak et al., the percentage of players with completed development of the hand skeleton both at the FIFA U-17 World Cup and at the AFC U-17 Championship decreased significantly from the first to the second tournament year. In the opinion of some authors, the assessment of hand skeleton maturity which has long been established for clinical age estimations must be challenged in the field of professional sport. In their view, this is at present not a reliable method of determining skeletal age, as verification of exact age is impossible due to the considerable scatter range of the developmental processes [31]. This argument fails to recognise that the individual scatter ranges of the most common methods of determining hand skeleton age have meanwhile been identified [32–37]. As is usual in forensic age estimation practice, falsifications of statements of chronological age can be undertaken on the basis of the minimum and maximum ages specific to the individual methods. With this in mind, estimation of hand skeleton age specifically is also well suited to use with professional footballers [8]. The stage classification of age-dependent ossification of the distal radial epiphysis put forward by Dvorak et al. was recently analysed in a direct comparison between diagnostic methods using magnetic resonance imaging and those using projection radiography [38]. An extremely good correlation was ascertained between the methodspecific diagnoses, on the one hand, as well as between the ossification stage determined by means of magnetic resonance imaging and the chronological age of the test persons, on the other. This underlines the fact that MRI diagnostic methods are in principle suitable for diagnosing the skeletal age of the hand. Differences in the results of the study which came to light at the same time were interpreted as an incorrect overestimation of chronological age in radiological diagnostics [38]. This interpretation fails to recognise that diagnosis of an epiphyseal ossification stage is clearly dependent upon the method used [39,40]. Therefore, as long as the ultimate age diagnosis in age estimation practice is based on a reference study using the identical method, corresponding differences can be offset. As magnetic resonance imaging is at present the only promising radiation-free—and thus admissible—method of estimating skeletal age in professional sport, the immense significance of an MRI reference study in assessing ossification of the distal radial epiphysis becomes all the more obvious. From today’s perspective, the studies which have been published on analysis of the maturation process of the distal radial epiphysis by means of magnetic resonance imaging appear in practice to be applicable only to a limited degree. Thus, the stage classification used by Dvorak et al. depends at least partially upon a survey of absolute linear values (ossification stage V [D]) which must in general be rated as not very objective criteria. Moreover, it became apparent in the course of practical application that the classification characteristics must be rated as comparatively insensitive criteria [7,31]. However, even more problematic in the final analysis is the simultaneous limited specificity of the criteria. Thus, in one of the 496 cases studied by Dvorak et al., positive evidence was incorrectly put forward that the U-17 age limit had been exceeded [9]. Practically applied, this would have led to unjustified
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Ossificaon stage IIIcIII c Ossifikaonsstadium
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Ossificaon stage IV IV Ossifikaonsstadium
70.00 % 60.00 % 50.00 % 40.00 % 30.00 % 20.00 % 10.00 % 0.00 % 18
19
20
21
22
Fig. 6. Percentage of evidence of a threefold stratification in the area of the former epiphyseal plate in ossification stages IIIc and IV of the distal radial epiphysis.
discrimination against the sportsman in question [12]. For this reason, to improve accuracy, it is necessary to include characteristics of maturity which do not develop in the distal radial epiphysis before completion of the 18th year of life. Given a correspondingly high minimum age, these characteristics would also be applicable to the falsification of age statements at U-20 tournaments. As a pilot study, the present research project addresses for the first time the applicability of the combination of the stage classifications of ossification proposed by Schmeling et al. [26] and by Kellinghaus et al. [27] in diagnosing epiphyseal ossification of the distal radius by means of magnetic resonance imaging. In so doing, the age range of the study population taken as a basis by Dvorak et al. [9] was shifted to 18 to 22 years so as to clarify the problem of the verifiability of higher age limits. By selecting a higher field strength of 3 T and reducing the slice thickness of the scan to be evaluated to 1 mm, it was also possible to achieve an improvement in the diagnostic potential. In this way, it was possible to assess the morphology of the epiphyseal scar, a characteristic of the advanced epiphyseal maturation process, particularly well. According to the results currently available, ossification stages IV and V, in particular, which are defined by the epiphyseal scar now make it possible to make statements on higher chronological age groups. In our study, ossification stage IV was detected at a minimum chronological age of 18.3 years. Even if the frequency with which this stage is detected increases with increasing chronological age, the minimum age found here is with great probability defined by the lower age limit of the study cohort. As ossification stage IV must be regarded by definition as the lower subset of ossification stage VI (D), it remains doubtful at present whether the minimum age of ossification stage IV can be used under the methodological conditions for age monitoring at U-17 professional football tournaments in our variation. A much more promising approach is offered by the observation that, according to the results of our study, in almost 50% of cases, the scar of ossification stage IV demonstrated at least partial threefold stratification in the area of the former epiphyseal plate. A comparable scar structure could only be documented in the ossified sections of the epiphyseal plate in ossification stage IIIc in a far smaller proportion of cases. However, until the 21st year of life, the frequency with which it appears in ossification stage IV with increasing age points to a phenomenon of the advanced maturation process. These differences in scar morphology are already an indication of the possibility of a sub-differentiation within ossification stage IV. Based on the minimum age of potential substages, reliable statements on age limits exceeded by professional footballers at FIFA U-17 World Cup tournaments would be conceivable.
In none of the sportsmen examined by us could an ossification stage V of the distal radial epiphysis be detected. Taking into account the maximum age of our study population, this makes it appear probable that the minimum age for entry into ossification stage V lies at over 22 years. Thus, evidence of such a state of maturity provided by magnetic resonance imaging would also open up the possibility of a falsification of the age given by professional footballers at FIFA U-20 World Cup tournaments. Limitations of our study include the examined age spectrum as well as the restriction to male test persons. Further MRI studies including older test persons will be necessary to verify our hypothesis that the disappearance of the epiphyseal scar in the distal radius provides evidence of completion of the 20th year of life. In addition, reference data for female test persons need to be gathered. 5. Novelty statement For the first time potential criteria for exceeding all relevant age limits in international football based on the ossified epiphyseal plate of the distal radius using MRI are presented. Acknowledgements The study was supported by FIFA-Medical Assessment and Research Centre (F-MARC). References [1] M. Kellinghaus, R. Schulz, V. Vieth, S. Schmidt, A. Schmeling, Forensic age estimation in living subjects based on the ossification status of the medial clavicular epiphysis as revealed by thin-slice multidetector computed tomography, Int. J. Legal Med. 124 (2010) 149–154. [2] A. Olze, J. Hertel, R. Schulz, T. Wierer, A. Schmeling, Radiographic evaluation of Gustafson's criteria for the purpose of forensic age diagnostics, Int. J. Legal Med. 126 (2012) 615–621. [3] A. Olze, P. van Niekerk, R. Schulz, S. Ribbecke, A. Schmeling, The influence of impaction on the rate of third molar mineralisation in male black Africans, Int. J. Legal Med. 126 (2012) 869–874. [4] S. Schmidt, I. Nitz, S. Ribbecke, R. Schulz, H. Pfeiffer, A. Schmeling, Skeletal age determination of the hand: a comparison of methods, Int. J. Legal Med. 127 (2013) 691–698. [5] S. Schmidt, M. Schiborr, H. Pfeiffer, A. Schmeling, R. Schulz, Age dependence of epiphyseal ossification of the distal radius in ultrasound diagnostics, Int. J. Legal Med. 127 (2013) 831–838. [6] S. Schmidt, M. Schiborr, H. Pfeiffer, A. Schmeling, R. Schulz, Sonographic examination of the apophysis of the iliac crest for forensic age estimation in living persons, Sci. Justice 53 (2013) 395–401. [7] L. Engebretsen, K. Steffen, R. Bahr, C. Broderick, J. Dvorak, P.-M. Janarv, A. Johnson, M. Leglise, T.C. Mamisch, D. McKay, L. Micheli, P. Schamasch, G.D. Singh, D.E.J. Stafford,
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[25b] J.A. Krämer, S. Schmidt, K.U. Jürgens, M. Lentschig, A. Schmeling, V. Vieth, Forensic age estimation in living individuals using 3.0 T MRI of the distal femur, Int. J. Legal Med. 128 (2014) 509–514; [25c] F. Dedouit, J. Auriol, H. Rousseau, D. Rougé, E. Crubézy, N. Telmon, Age assessment by magnetic resonance imaging of the knee: a preliminary study, Forensic Sci. Int. 217 (2012) 232.e1–232.e7; [25d] S. Dreizen, R.M. Snodgrasse, H. Webb-Peploe, G.S. Parker, T.D. Spies, Bilateral symmetry of skeletal maturation in the human hand and wrist, American Medical Association, J. Dis. Child. 93 (1957) 122–127. A. Schmeling, R. Schulz, W. Reisinger, M. Mühler, K.D. Wernecke, G. Geserick, Studies on the time frame for ossification of the medial clavicular epiphyseal cartilage in conventional radiography, Int. J. Legal Med. 118 (2004) 5–8. M. Kellinghaus, R. Schulz, V. Vieth, S. Schmidt, H. Pfeiffer, A. Schmeling, Enhanced possibilities to make statements on the ossification status of the medial clavicular epiphysis using an amplified staging scheme in evaluating thin-slice CT scans, Int. J. Legal Med. 124 (2010) 321–325. D.G. Altman, Practical Statistics for Medical Research, Chapman & Hall, New York, 1991. J. Dvorak, J. George, A. Junge, J. Hodler, Application of MRI of the wrist for age determination in international U-17 soccer competitions, Br. J. Sports Med. 41 (2007) 497–500. R.M. Malina, Growth and maturity status of young soccer players, in: T. Reilly, A.M. Williams (Eds.), Science and Soccer, Routledge, London, 2003, pp. 287–306. R.M. Malina, M.E. Peña Reyes, A.J. Figueiredo, M.J. Coelho, E. Silva, L. Horta, R. Miller, M. Chamorro, L. Serratosa, F. Morate, Skeletal age in youth soccer players: implication for age verification, Clin. J. Sport Med. 20 (2010) 469–474. S. Schmidt, B. Koch, M. Mühler, W. Reisinger, A. Schmeling, Optimizing the Thiemann-Nitz method for skeletal age determination for forensic age diagnostics in live subjects Scandinavian, J. Forensic Sci. 13 (2007) 5–7. S. Schmidt, B. Koch, R. Schulz, W. Reisinger, A. Schmeling, Studies in use of the Greulich-Pyle skeletal age method to assess criminal liability, Legal Med. 10 (2008) 190–195 (Tokyo, Japan). S. Schmidt, I. Nitz, R. Schulz, A. Schmeling, Applicability of the skeletal age determination method of Tanner and Whitehouse for forensic age diagnostics, Int. J. Legal Med. 122 (2008) 309–314. U. Baumann, R. Schulz, A. Heinecke, A. Schmeling, S. Schmidt, Reference study on the time frame for ossification of the distal radius and ulnar epiphysis on the hand radiograph, Forensic Sci. Int. 191 (2009) 15–18. S. Schmidt, I. Nitz, R. Schulz, M. Tsokos, A. Schmeling, The digital atlas of skeletal maturity by Gilsanz and Ratib: a suitable alternative for age estimation of living individuals in criminal proceedings? Int. J. Legal Med. 123 (2009) 489–494. M. Tisè, L. Mazzarini, G. Fabrizzi, L. Ferrante, R. Giorgetti, A. Tagliabracci, Applicability of Greulich and Pyle method for age assessment in forensic practice on an Italian sample, Int. J. Legal Med. 125 (2011) 411–416. J. George, J. Nagendran, K. Azmi, Comparison study of growth plate fusion using MRI versus plain radiographs as used in age determination for exclusion of overaged football players, Br. J. Sports Med. 46 (2012) 273–278. R. Schulz, M. Mühler, W. Reisinger, S. Schmidt, A. Schmeling, Radiographic staging of ossification of the medial clavicular epiphysis, Int. J. Legal Med. 122 (2008) 55–58. V. Vieth, M. Kellinghaus, R. Schulz, H. Pfeiffer, A. Schmeling, Beurteilung des Ossifikationsstadiums der medialen Klavikulaepiphysenfuge Vergleich von Projektionsradiographie, Computertomographie und Magnetresonanztomographie, Rechtsmedizin 20 (2010) 483–488.
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Examination of ossification of the distal radial epiphysis using magnetic resonance imaging. New insights for age estimation in young footballers in FIFA tournaments S. Schmidt a, V. Vieth b, M. Timme a, J. Dvorak c,d, A. Schmeling a,⁎ a
Institute of Legal Medicine, University Hospital Münster, Röntgenstraße 23, D-48149 Münster, Germany Institute of Clinical Radiology, University Hospital Münster, Albert-Schweitzer-Campus 1, D-48149 Münster, Germany c Department of Neurology, Schultheiss Clinic, Lengghalde 2, CH-8008 Zurich, Switzerland d FIFA Medical Assessment and Research Centre (F-MARC), Schultheiss Clinic, Lengghalde 2, CH-8008 Zurich, Switzerland b
a r t i c l e
i n f o
Article history: Received 7 August 2014 Received in revised form 26 November 2014 Accepted 10 December 2014 Keywords: forensic age diagnosis skeletal age hand radius MRI
a b s t r a c t Alongside a variety of clinical and forensic issues, age determination in living persons also plays a decisive role in the field of professional sport. Only methods of determining skeletal age which do not expose individuals to ionizing radiation are suitable for this purpose. The present study examines whether MRI diagnosis of the distal radial epiphysis can be utilised to monitor internationally relevant age limits in professional football. The wrist area of 152 male footballers aged 18 to 22 years belonging to regional clubs was prospectively examined using MRI. The ossification stage of the distal radial epiphysis was subsequently determined on the basis of established criteria used in determining the maturity of the medial clavicular epiphysis. For the first time, we ascertained evidence of an increase in the prevalence of the phenomenon of threefold linear stratification (hypointense line, hyperintense line, and hypointense line) in the representation of the fused epiphyseal plate of the radius using magnetic resonance imaging with increasing chronological age. Within our study population, test persons with an ossified epiphyseal plate without any verifiable epiphyseal scar were not represented. The presumably high minimum age of entry into this final stage of development (N 22 years) must be verified in the course of further studies. According to the results of the present study, the fused epiphyseal plate of the distal radius provides potential maturation criteria which appear suitable for reliable monitoring of all relevant age limits in international football with the aid of magnetic resonance imaging. © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.
1. Introduction Over the past 20 years, scientific insights gained in the field of age diagnosis in living persons have been mainly inspired in an almost unprecedented manner by the specific requirements of practical forensic work [1–6]. However, application of the results of this development is not restricted to conventional medical and legal contexts. Thus, the methods used to clarify the stated age of living individuals are also gaining increasing significance in the organisation of elite sporting competitions [7]. In this context, it is the primary responsibility of international sporting federations to guarantee by means of age divisions that all participants enjoy the equal opportunities required for ethical reasons. At the same time, any physical and/or psychological and social strain on sportspeople not in line with their age is to be avoided as a significant source of self-endangerment in relation to health. Finally, with regard to contact and collision sports, in particular, it is also important ⁎ Corresponding author. Tel.: + 49 251 83 55 156; fax: + 49 251 83 55 158. E-mail address: [email protected] (A. Schmeling).
to protect physically weaker team members from injuries caused by older players. Tournaments organised by the Fédération Internationale de Football Association (FIFA) as an international football governing body include the U-17 and U-20 World Cups. These are both staged between the best junior male national teams in uneven years and the best junior female national teams in even years. In these competitions, all male and female footballers are entitled to play if they reach the relevant age limits on 1 January of the year of the Cup Final at the earliest. More specifically, therefore, participation following completion of the 18th or 21st year of life, respectively, is excluded. The age range between 15 and 23 years in both sexes is highly relevant to international youth football for the various championship tournaments organised by the continental federations subordinate to FIFA. The identity of all participants is monitored by the organisers in the run-up to each football tournament on the basis of personal documents, such as ID cards, passports, birth certificates, etc. On a number of occasions in the past, suspicions have arisen that the age stated for individual junior players was incorrectly low [7–9]. A certain proportion of
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cases may be due to delayed, sometimes unsupported, in some places even completely lacking, registration of births, such as is the case especially in various countries of origin for geographic and cultural reasons. However, cases of criminally motivated misdeclarations in the sense of so-called “age doping” can also scarcely be ignored. By this means, the chances of an individual player to be signed by a renowned football club may possibly be increased [10]. In general, however, the illicit participation of older players also wrongfully enhances the prospects of a team victory in age-restricted football tournaments. In recent times, questions relative to the general meaningfulness and the ideal means of monitoring age in professional youth football have repeatedly been the subject of scientific debate [11,12]. In view of the fact that the genetically determined maturation sequences of individual osseous elements occur within a certain range of variation with a comparatively high level of regularity [13–16], skeletal maturation can still be considered the most significant indicator of biological age. However, the X-ray examinations required for the majority of established methods of determining skeletal age are not legally justified in the field of sport, and in the judgment of the International Olympic Committee (IOC), cannot be advocated according to sports ethics [7]. For this reason, future research efforts in this area must be mainly focussed on further establishing examination methods for purposes of skeletal age diagnosis which do not expose the individual to ionizing radiation. So far, a number of general approaches to resolving this problem have been highlighted [17–25,25a,25b,25c]. Initial trendsetting attempts have been undertaken to routinely apply such methods using magnetic resonance imaging to ascertain the ossification stage of the distal radial epiphysis to determine the age of professional footballers [9]. The objective of the present pilot study is to examine whether MRI diagnosis of the distal radial epiphysis can be utilised to monitor internationally relevant age limits in professional football. 2. Test persons and methods The tests encompassed the prospective evaluation of magnetic resonance imaging scans of the area of the left wrist in a total of 152 German male volunteers aged between 18 and 22 years. All details of age were monitored on the basis of a tendered official identification document. The 18-, 19-, and 21-year-old age groups each comprised 30 persons, the 20- and 22-year-old age groups 31 persons. The study population was comprised of amateur footballers who were enrolled at the time of the study as active players in a club registered with the German Football Federation. Growth disorders were ruled out when collecting the medical history of the test persons. All the MRI examinations on which the study is based were performed in the months from February to June 2011 at the Institute of Clinical Radiology of the University Hospital Münster (Germany). The project was supported by a positive vote of the ethics commission responsible; this vote was based on a comprehensive explanation of risks and the written declaration of consent given by all test persons. The imaging diagnostics were performed on a 3.0 T scanner (Achieva, Philips Medical Systems, Netherlands) using a surface coil (Sense Flex M, Philips Medical Systems, Netherlands). Based on clinical radiological methods of hand age diagnosis, a T1-weighted turbo spin echo (T1-TSE) sequence in coronal sectional orientation (TR: 635 ms; TE: 11 ms; FA: 90°; NSA: 3; FoV: 100 × 100 mm; slice thickness: 1.5 mm; scan time: 6.0 min; measured matrix: 248 × 180 [m × p]; measured voxel size: 0.4 × 0.5 × 1.5 mm; recon voxel size: 0.2 × 0.19 × 1.5 mm) was used for image acquisition so as to achieve a scan of as long a section of the distal radial epiphysis as possible. Only scans of the left hand were included in the investigation, as significant traumatic changes to the right hand are more prevalent in the population as a whole. Potential differences between the sides in the degree of maturation do not represent a relevant source of error in determining the age of the hand skeleton [25d].
A ViewForum Workstation (Philips Medical Systems, Netherlands) with a diagnostic monitor was available for masked assessment of the MR scans. To determine the ossification stage of the distal radial epiphysis, a combination of the classification systems proposed by Schmeling et al. [26] and by Kellinghaus et al. [27] was used (Table 1). When determining the ossification stage, the entire image sequence generated for each test person was evaluated. When determining stages 2 and 3 (including substages), the slice with the most advanced degree of ossification was selected in each case. Stage 4 was determined whenever the growth plate was fully ossified in all the slices and an epiphyseal scar or the remains of one were visible in at least one slice. Stage 5 was determined whenever the growth plate was fully ossified in all the slices and no traces of any epiphyseal scar were visible in any of the slices. All the images were first evaluated by an examiner (forensic physician) with experience in skeletal age determination. This first examiner evaluated 30 cases for a second time after a time lapse of three months. In the case of this partial group, a further evaluation was performed by a second examiner (forensic physician) who also had wide experience in skeletal age determination. All evaluations were performed without knowledge of the age and sex of the individuals examined. We used SPSS 16.0.1 (IBM SPSS Statistics) software for the statistical evaluation of the data. A variety of statistical measures (minimum age, maximum age, mean value with standard deviation, and median with lower and upper quartiles) were calculated to describe the individual ossification stages. The kappa coefficients were calculated to determine intra- and interobserver agreement.
3. Results Figs. 1 to 5 illustrate the characteristic MRI findings of ossification stages IIc, IIIa, IIIb, IIIc, and IV of the distal radial epiphysis which were detected in the study population. Ossification stages I, IIa, IIb, and V were not found amongst our test persons. In all cases included in the study, it was possible to determine the ossification stage of the distal radial epiphysis using magnetic resonance imaging. For intraobserver agreement, a kappa coefficient of 0.94 was calculated. According to the verbal ratings proposed by Altman [28], this corresponds to a very good level of agreement. For interobserver agreement, a kappa coefficient of 0.88 was calculated. This value also corresponds to a very good level of agreement. Ossification stages IIc and IIIa were established exclusively in the 18-year-old age group, whilst ossification stage IIIb was found only in the 18- and 19-year-old age groups. Within the studied age spectrum as a whole, ossification stage IIIc was ascertained with decreasing frequency as chronological age increased, whilst ossification stage IV became increasingly frequent. Table 1 Stage classification of ossification of the distal radial epiphysis modified according to Schmeling et al. [26] and Kellinghaus et al. [27]. Stage Description I IIa IIb IIc IIIa IIIb IIIc IV V
The epiphysis has not yet ossified The length of the ossified epiphysis is one-third or less compared to the width of the metaphyseal ending The length of the ossified epiphysis is between one-third and two-thirds compared to the width of the metaphyseal ending The length of the ossified epiphysis is over two-thirds compared to the width of the metaphyseal ending Epiphyseal–metaphyseal fusion completes one-third or less of the epiphyseal plate Epiphyseal–metaphyseal fusion completes between one-third and two-thirds of the epiphyseal plate Epiphyseal–metaphyseal fusion completes over two-thirds of the epiphyseal plate The epiphyseal plate is fully ossified and the epiphyseal scar is visible The epiphyseal plate is fully ossified and the epiphyseal scar is no longer visible
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Fig. 1. MRI sectional image of an ossification stage IIc of the distal radial epiphysis. The lengthwise epiphyseal measurement is over two-thirds compared to the widthwise measurement of the metaphyseal ending.
Fig. 3. MRI sectional image of an ossification stage IIIb of the distal radial epiphysis. The epiphyseal–metaphyseal fusion (arrows) completes over one-third but less than twothirds of the former gap between epiphysis and metaphysis.
Table 3 displays the measures of location and dispersion relating to the statistical description of the ossification stages determined. The measures demonstrate an increase in the mean values and medians of the chronological age of the test persons with an increase in the ossification stage of the distal radial epiphysis. Twenty-five of the 82 cases studied which were classified as ossification stage IIIc (30.5%) each displayed a threefold stratification (hypointense line, hyperintense line, hypointense line) within the fused parts of the epiphyseal plate which has not previously been described. Thirty-one of the 64 cases studied which were classed as ossification stage IV (48.4%) displayed the same findings. In the diagram broken down by increasing chronological age (Fig. 6), it becomes clear that the frequency with which this morphological constellation can be attested in ossification stage IIIc tends to decrease, whereas in ossification stage IV, it increases until completion of the 22nd year of life.
Based on established radiological methods, the potentialities of determining age in the sport of football by determining hand skeleton
maturity by means of magnetic resonance imaging, without exposure to ionizing radiation, were published as early as 2007 [9]. For this purpose, the authors had examined a total of 496 healthy male football players in the age groups from 14 to 19 years, with reliable dates of birth, from a variety of national and regional federations in Switzerland, Malaysia, Algeria, and Argentina. Using the results obtained, they compiled a classification system based on the stages of the process of ossification of the distal radial epiphysis (Table 2; hereafter ossification stages according to D). For this grading, a significant correlation between the ossification stage and the chronological age of the individual as well a high level of intra- and interobserver agreement were established. The practical applicability of the method developed by Dvorak et al. was tested when ages were verified at four U-17 football tournaments by the authors themselves [29]. The analysis included 189 players who were selected as random samples from the 16 teams participating at each of the following: the FIFA U-17 World Cup in Finland (2003), the AFC U-17 Championship in Japan (2004), the FIFA U-17 World Cup in Peru (2005), and the AFC U-17 Championship in Singapore (2006). Compared with the previous study, it became apparent that U-17
Fig. 2. MRI sectional image of an ossification stage IIIa of the distal radial epiphysis. The epiphyseal–metaphyseal fusion (arrow) completes less than one-third of the former gap between epiphysis and metaphysis.
Fig. 4. MRI sectional image of an ossification stage IIIc of the distal radial epiphysis. The epiphyseal–metaphyseal fusion completes over two-thirds of the former gap between epiphysis and metaphysis.
4. Discussion
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S. Schmidt et al. / Science and Justice 55 (2015) 139–144 Table 3 Statistical measures (in years).
Fig. 5. MRI sectional Image of an ossification stage IV of the distal radial epiphysis. The epiphyseal cartilage is fully ossified. Note the partial threefold stratification in the area of the former epiphyseal plate (arrow).
professional footballers displayed a higher skeletal age on average than was the case in players of the corresponding age in the reference population. In the view of the authors, this fact suggests the initial suspicion that the ages given in the official documents of the U-17 players examined were not correct in every case. The implication that some footballers gained advantages for themselves and/or their teams in U-17 tournaments by giving incorrect ages became the object of extensive criticism of the study by Dvorak et al. [12]. The key point in the counterargument is the statement that a tendency towards acceleration in skeletal age can be observed in sub-elite and elite groups of football players, particularly after the 13th to 14th year of life [30,31]. The discrepancies ascertained among professional teams were seen as a consequence of a selection of particularly high-powered early developers from the overall pool of all football players developing in accordance with their age [31]. However, the extent to which the ages given by the participants in the study by Malina et al. were reliable remains unclear. The possibility of a selective influence on the skeletal age distribution of professional footballers was also discussed by Dvorak et al. [29]. In spite of this, the study presented some particularly unusual results which could not easily be reconciled with such an assumption. Thus, there was no significant correlation between the ossification stages of the distal radial epiphysis determined by magnetic resonance imaging on the one hand, and the chronological age groups on the other, in the study cohort of professional players as compared with the reference population of male footballers. Moreover, in the 14-year-old age group, three out of eight sportspersons displayed an ossification stage VI (D), whilst two manifested an ossification stage V (D). By contrast, in the corresponding age group in the reference population, none of the ossification stages IV (D), V (D), or VI (D) were ascertained [9]. A selection effect would give reason to expect that the proportion of Table 2 Stage classification of ossification of the distal radial epiphysis using magnetic resonance imaging according to Dvorak et al. [9]. Stage
Description
I II III IV V VI
Completely unfused Early fusion: minimal hyperintensity within the physis Trabecular fusion of b50% of the radial cross-sectional area Trabecular fusion of N50% of the radial cross-sectional area Residual physis, b5 mm on any one section Completely fused
Stage
Number of cases
Minimum
Maximum
Mean value; standard deviation
Lower quartile; median; upper quartile
IIc IIIa IIIb IIIc IV
1 2 3 82 64
18.6 18.1 18.6 18.1 18.3
18.6 18.8 19.7 22.8 22.9
– 18.4 ± 0.4 19.2 ± 0.6 20.3 ± 1.4 21.1 ± 1.3
– 18.1; 18.4; – 18.6; 19.4; – 19.0; 20.2; 21.5 20.3; 21.1; 22.3
higher ossification stages would increase within an age group. This hypothesis, however, does not explain why these stages occur several years earlier in the selected sample than in the normal population. Finally, following the commencement of random age checks by Dvorak et al., the percentage of players with completed development of the hand skeleton both at the FIFA U-17 World Cup and at the AFC U-17 Championship decreased significantly from the first to the second tournament year. In the opinion of some authors, the assessment of hand skeleton maturity which has long been established for clinical age estimations must be challenged in the field of professional sport. In their view, this is at present not a reliable method of determining skeletal age, as verification of exact age is impossible due to the considerable scatter range of the developmental processes [31]. This argument fails to recognise that the individual scatter ranges of the most common methods of determining hand skeleton age have meanwhile been identified [32–37]. As is usual in forensic age estimation practice, falsifications of statements of chronological age can be undertaken on the basis of the minimum and maximum ages specific to the individual methods. With this in mind, estimation of hand skeleton age specifically is also well suited to use with professional footballers [8]. The stage classification of age-dependent ossification of the distal radial epiphysis put forward by Dvorak et al. was recently analysed in a direct comparison between diagnostic methods using magnetic resonance imaging and those using projection radiography [38]. An extremely good correlation was ascertained between the methodspecific diagnoses, on the one hand, as well as between the ossification stage determined by means of magnetic resonance imaging and the chronological age of the test persons, on the other. This underlines the fact that MRI diagnostic methods are in principle suitable for diagnosing the skeletal age of the hand. Differences in the results of the study which came to light at the same time were interpreted as an incorrect overestimation of chronological age in radiological diagnostics [38]. This interpretation fails to recognise that diagnosis of an epiphyseal ossification stage is clearly dependent upon the method used [39,40]. Therefore, as long as the ultimate age diagnosis in age estimation practice is based on a reference study using the identical method, corresponding differences can be offset. As magnetic resonance imaging is at present the only promising radiation-free—and thus admissible—method of estimating skeletal age in professional sport, the immense significance of an MRI reference study in assessing ossification of the distal radial epiphysis becomes all the more obvious. From today’s perspective, the studies which have been published on analysis of the maturation process of the distal radial epiphysis by means of magnetic resonance imaging appear in practice to be applicable only to a limited degree. Thus, the stage classification used by Dvorak et al. depends at least partially upon a survey of absolute linear values (ossification stage V [D]) which must in general be rated as not very objective criteria. Moreover, it became apparent in the course of practical application that the classification characteristics must be rated as comparatively insensitive criteria [7,31]. However, even more problematic in the final analysis is the simultaneous limited specificity of the criteria. Thus, in one of the 496 cases studied by Dvorak et al., positive evidence was incorrectly put forward that the U-17 age limit had been exceeded [9]. Practically applied, this would have led to unjustified
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Ossificaon stage IIIcIII c Ossifikaonsstadium
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Ossificaon stage IV IV Ossifikaonsstadium
70.00 % 60.00 % 50.00 % 40.00 % 30.00 % 20.00 % 10.00 % 0.00 % 18
19
20
21
22
Fig. 6. Percentage of evidence of a threefold stratification in the area of the former epiphyseal plate in ossification stages IIIc and IV of the distal radial epiphysis.
discrimination against the sportsman in question [12]. For this reason, to improve accuracy, it is necessary to include characteristics of maturity which do not develop in the distal radial epiphysis before completion of the 18th year of life. Given a correspondingly high minimum age, these characteristics would also be applicable to the falsification of age statements at U-20 tournaments. As a pilot study, the present research project addresses for the first time the applicability of the combination of the stage classifications of ossification proposed by Schmeling et al. [26] and by Kellinghaus et al. [27] in diagnosing epiphyseal ossification of the distal radius by means of magnetic resonance imaging. In so doing, the age range of the study population taken as a basis by Dvorak et al. [9] was shifted to 18 to 22 years so as to clarify the problem of the verifiability of higher age limits. By selecting a higher field strength of 3 T and reducing the slice thickness of the scan to be evaluated to 1 mm, it was also possible to achieve an improvement in the diagnostic potential. In this way, it was possible to assess the morphology of the epiphyseal scar, a characteristic of the advanced epiphyseal maturation process, particularly well. According to the results currently available, ossification stages IV and V, in particular, which are defined by the epiphyseal scar now make it possible to make statements on higher chronological age groups. In our study, ossification stage IV was detected at a minimum chronological age of 18.3 years. Even if the frequency with which this stage is detected increases with increasing chronological age, the minimum age found here is with great probability defined by the lower age limit of the study cohort. As ossification stage IV must be regarded by definition as the lower subset of ossification stage VI (D), it remains doubtful at present whether the minimum age of ossification stage IV can be used under the methodological conditions for age monitoring at U-17 professional football tournaments in our variation. A much more promising approach is offered by the observation that, according to the results of our study, in almost 50% of cases, the scar of ossification stage IV demonstrated at least partial threefold stratification in the area of the former epiphyseal plate. A comparable scar structure could only be documented in the ossified sections of the epiphyseal plate in ossification stage IIIc in a far smaller proportion of cases. However, until the 21st year of life, the frequency with which it appears in ossification stage IV with increasing age points to a phenomenon of the advanced maturation process. These differences in scar morphology are already an indication of the possibility of a sub-differentiation within ossification stage IV. Based on the minimum age of potential substages, reliable statements on age limits exceeded by professional footballers at FIFA U-17 World Cup tournaments would be conceivable.
In none of the sportsmen examined by us could an ossification stage V of the distal radial epiphysis be detected. Taking into account the maximum age of our study population, this makes it appear probable that the minimum age for entry into ossification stage V lies at over 22 years. Thus, evidence of such a state of maturity provided by magnetic resonance imaging would also open up the possibility of a falsification of the age given by professional footballers at FIFA U-20 World Cup tournaments. Limitations of our study include the examined age spectrum as well as the restriction to male test persons. Further MRI studies including older test persons will be necessary to verify our hypothesis that the disappearance of the epiphyseal scar in the distal radius provides evidence of completion of the 20th year of life. In addition, reference data for female test persons need to be gathered. 5. Novelty statement For the first time potential criteria for exceeding all relevant age limits in international football based on the ossified epiphyseal plate of the distal radius using MRI are presented. Acknowledgements The study was supported by FIFA-Medical Assessment and Research Centre (F-MARC). References [1] M. Kellinghaus, R. Schulz, V. Vieth, S. Schmidt, A. Schmeling, Forensic age estimation in living subjects based on the ossification status of the medial clavicular epiphysis as revealed by thin-slice multidetector computed tomography, Int. J. Legal Med. 124 (2010) 149–154. [2] A. Olze, J. Hertel, R. Schulz, T. Wierer, A. Schmeling, Radiographic evaluation of Gustafson's criteria for the purpose of forensic age diagnostics, Int. J. Legal Med. 126 (2012) 615–621. [3] A. Olze, P. van Niekerk, R. Schulz, S. Ribbecke, A. Schmeling, The influence of impaction on the rate of third molar mineralisation in male black Africans, Int. J. Legal Med. 126 (2012) 869–874. [4] S. Schmidt, I. Nitz, S. Ribbecke, R. Schulz, H. Pfeiffer, A. Schmeling, Skeletal age determination of the hand: a comparison of methods, Int. J. Legal Med. 127 (2013) 691–698. [5] S. Schmidt, M. Schiborr, H. Pfeiffer, A. Schmeling, R. Schulz, Age dependence of epiphyseal ossification of the distal radius in ultrasound diagnostics, Int. J. Legal Med. 127 (2013) 831–838. [6] S. Schmidt, M. Schiborr, H. Pfeiffer, A. Schmeling, R. Schulz, Sonographic examination of the apophysis of the iliac crest for forensic age estimation in living persons, Sci. Justice 53 (2013) 395–401. [7] L. Engebretsen, K. Steffen, R. Bahr, C. Broderick, J. Dvorak, P.-M. Janarv, A. Johnson, M. Leglise, T.C. Mamisch, D. McKay, L. Micheli, P. Schamasch, G.D. Singh, D.E.J. Stafford,
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