• Based on prospective referential data a new MRI classification was formulated. • The setting allows assessment of the age of an individual's skeletal development. • The classification scheme allows the reliable determination of majority in both sexes. • The staging shows a high reproducibility for instructed and trained professional personnel. • The proposed classification is likely to be adaptable to other long bone epiphyses.

• Forensic age estimation by means of MRI of the knee is feasible. • MRI provides data about the ossification process without using ionising radiation. • The method allows the determination of the 14th and 16th years of life. • The bony fusion is not suitable as the sole indicator of majority. • The chosen classification is easy to use for specially trained professional personnel.

Evaluation of the degree of ossification of the medial clavicular epiphysis plays a crucial role in determining with an adequate degree of probability whether legally relevant age boundaries after the age of 17 have been crossed. In view of the need to avoid unnecessary radiation exposure, establishing non-X-ray methods for investigating the clavicle has long been a key objective in forensic age assessment research. Based on magnetic resonance imaging examinations in a large sample of healthy subjects, the current study for the first time presents statistical measures which allow inferences to be drawn for forensic age assessment in both sexes. We undertook a prospective study of a reference sample of 334 female and 335 male German volunteers aged from 12 to 24 using a 3-T MRI scanner. A 3D FFE (fast field echo) T1-weighted sequence with fat saturation was acquired. To stage ossification of the medial clavicular epiphysis, we used the clavicular ossification staging systems described by Schmeling et al. and Kellinghaus et al. Ossification stage IIIc offers a means in both sexes of demonstrating that the age of 18 has been attained prior to complete ossification of the epiphyseal plate. In both sexes, if a subject has reached ossification stage IV, it can be stated that he or she has attained the age of 21. Magnetic resonance imaging is a valid diagnostic procedure for determining the ossification stage of the medial clavicular epiphysis.

As superimposition effects often impede the evaluation of the ossification status of the medial clavicular epiphysis in standard posterior-anterior (PA) radiographs, additional oblique images (right anterior oblique, RAO, and left anterior oblique, LAO) are currently recommended to allow for reliable stage assessments. The present study examines the influence of the radiographic projection type on stage determination. To this end, 836 sternoclavicular joints were prospectively obtained during forensic autopsies of bodies aged between 15 and 30 years. Subsequently, three different radiographs (PA, RAO, and LAO) were taken from each specimen and separately evaluated as to the developmental stage of the medial clavicular epiphysis. A forensically established five-stage classification system was used. In 25 % of the cases, the medial clavicular epiphysis depicted in an oblique projection showed a different ossification stage than in the PA projection. In at least 10 % of the cases, a higher ossification stage was observed which would have significant disadvantages in criminal proceedings (ethically unacceptable error). In conclusion, the usage of the current radiographic reference data, which rely upon chest radiographs taken as PA projections, appears to be inadmissible for oblique projections. Projection radiography of the clavicle can therefore no longer be recommended for forensic age estimation practice. As to the question of whether an individual has achieved the age of 18 or 21, computed tomography of the clavicle must be regarded as the exclusive method of choice.

The radiological investigation of the ossification stage of the medial clavicular epiphysis represents the crucial tool for assessing whether a living individual has completed the age of 18 years. However, exposure to radiation cannot always be accepted due to legal reasons and radiation-free methods still lack reference data or are not available. Therefore, this study examines the role of pre-existing radiographic material of the clavicles, making it necessary to prospectively validate the established five-stage classification system for evaluating the clavicular ossification process as well as to enlarge the so far very limited pool of available reference data. Accordingly, standard posterior-anterior projection radiographs of 836 sternoclavicular joints prospectively obtained during 418 forensic autopsies (age range 15-30 years) were analyzed. Stage III was first found at ages 16 and 15 (males/females), stage IV at ages 22 and 21 (males/females), and stage V at age 26 in both sexes. The presented results principally corroborate the previous reference data from 2004, suggesting reliability of the five-stage classification system. In conclusion, chest radiographs may still be useful for forensic age diagnostics in living individuals but only in certain cases. In age estimations which can be planned in advance, projection radiography of the clavicle must still be considered obsolete.