Correlation between age and ossification of the medial epiphysis of the collar bone

1. Correlation between age and ossification of the medial epiphysis of the collar bone Andreas SchmelingInstitute of Legal MedicineUniversity of Münster

2. Recommendations of the Study Group on Forensic Age Diagnostics • Physical examination • X-ray of the hand • Dental examination • Radiographic or CT examination of the clavicles

3. Studies on clavicular ossification

4. Studies CR CT MRI US CT slice thickness Comparison CR-CT

5. Studies CR

6. CR Material and methods • Retrospective evaluation of 873 plain chest radiographs taken between 1995 and 2002 at the University Hospital Charité Berlin requested by the staff medical officer • Subjects: healthy members of staff (530 females, 343 males) aged 16–30 • In 174 X-rays assessment impossible on both sides due to overlaps or developmental anomalies • 699 X-rays assessable

7. CR Ossification stages 2 3 4 5 1 The ossification centre has not yet ossified The ossification centre has ossified, the epiphyseal cartilage has not ossified The epiphyseal cartilage is partially ossified The epiphyseal cartilage is fully ossified; the epiphyseal scar is visible The epiphyseal cartilage has fused completely; the epiphyseal scar is no longer visible

8. CR Example I male,17 years, stage 2

9. CR Example II female,30 years, stage 5

10. CR Results min = minimum, max = maximum, SD = standard deviation

11. CR Conclusions • Conventional radiographs can be used to assess clavicular ossification. • If an evaluation is not possible in p.a. views because of overlaps, anterior oblique views should also be taken.

12. Studies CR CT

13. CT Material and methods • Retrospective analysis of 629 CT images of patients aged between 15 and 30 years produced during trauma diagnostics at the Accident Hospital Berlin • 40 CT scans excluded because the exact ages of the patients could not be verified, 33 cases excluded because of contrast medium artefacts, developmental anomalies or fractures • 556 CT images assessable (546 x 7mm, 2 x 5 mm, 4 x 3 mm, 1 x 2 mm, 3 x 1 mm)

14. CT Ossification stages 2 3 4 5 1 The ossification centre has not yet ossified The ossification centre has ossified, the epiphyseal cartilage has not ossified The epiphyseal cartilage is partially ossified The epiphyseal cartilage is fully ossified; the epiphyseal scar is visible The epiphyseal cartilage has fused completely; the epiphyseal scar is no longer visible

15. CT Example I male,17 years, stage 2

16. CT Results min = minimum, max = maximum, SD = standard deviation

17. CT Conclusions • The 5 stages of clavicular ossification can also be observed on CT scans. • Stage 5 was four or five years earlier observed than in the CR study. • In CT scans of high slice thickness (98 % of cases) the epiphyseal scar may be masked as a result of the partial-volume effect. • The influence of slice thickness on assessment of clavicular ossification should be examined in further studies.

18. Studies CR CT CT slice thickness

19. CT slice thickness Material and methods • Retrospective analysis of CT scans of 40 living subjects (2 women, 38 men), originally performed for the purpose of forensic age estimation • From the data acquired images with slice thicknesses of 1, 3, 5 and 7 mm were reconstructed • Determination of the respective ossification stage for each reconstructed slice thickness, separately for both sides (n=80)

20. CT slice thickness Results

21. CT slice thickness Example

22. CT slice thickness Conclusions • The slice thickness of CT scans has a crucial impact on the evaluation of clavicle ossification status. • Even slice thicknesses of 1 and 3 mm led to different ossification stages. • For forensic age estimation purposes the slice thickness should be 1 mm to ensure maximum diagnostic reliability.

23. Studies CR CT CT slice thickness Comparison CR-CT

24. Comparison CR-CT Material and methods • Retrospective comparative assessment of p.a. conventional radiographs and CT scans (slice thickness 1 mm) of the sternoclavicular joints of 57 living subjects (= 114 clavicles) examined for forensic age estimation purposes between 2003 and 2005 • Using CT a determination of the ossification stage was possible in all cases; using CR a determination was not possible in 15 cases due to overlaps • 99 clavicles were available for comparison

25. Comparison CR-CT Results

26. Comparison CR-CT Example P.D., Stage 3 (right) P.D., Stage 2 (right)

27. Comparison CR-CT Conclusions • CR and CT did not produce identical stages in 2 cases. • In forensic age estimation practice, it is necessary that CR reference studies be used for ossification stage classification by CR and CT reference studies be used for ossification stage classification by CT. • Further studies are required in order to make a recommendation as to whether three-plane CR or CT is the method of choice for assessment of clavicular ossification.

28. Studies MRI CR CT CT slice thickness Comparison CR-CT

29. MRI Material and methods • Prospective analysis of MR scans of sternoclavicular joints of 54 bodies aged between 6 and 40 years, gained in the course of forensic autopsies • Sternoclavicular joints were kept deep frozen at −20 °C for at most 3 months after autopsy • Before MR examinations, each preparation was defrosted at room temperature (20 °C) for 24 h

30. MRI Ossification stages 1 2 3 4 The ossification centre has not yet ossified The ossification centre has ossified, the epiphyseal cartilage has not ossified The epiphyseal cartilage is partially ossified The epiphyseal cartilage is fully ossified

31. MRI Example I female22 years stage 3

32. MRI Example II male36 years stage 4

33. MRI Results min = minimum, max = maximum, SD = standard deviation

34. MRI Conclusions • The stage of clavicular ossification could be assessed in all cases. • The determined age intervals of the respective ossification stages correspond to the known data from CR and CT studies. • The results should be confirmed with a larger number of cases. • A modified examination protocol is required for the MRI of living individuals.

35. Studies MRI CR CT US CT slice thickness Comparison CR-CT

36. US Material and methods • Prospective evaluation of the right medial clavicular epiphyses of 84 healthy volunteers aged between 12 and 30 years by means of ultrasound • In 4 cases an assessment was not possible due to developmental anomalies. • Ossification stage classification was possible in 80 cases.

37. US Ossification stages 3 1 2 4 Ultrasonic gap between the medial end and the ossification center Acute angle configuration of the medial end; no ossification center Both an ultrasonic gap with an ossification center and a completely fused epiphysis Completely fused epiphysis with convex configuration of the medial end

38. US Example I female, 18 years, stage 2

39. US Example II female, 23 years, stage 4

40. US Results min = minimum, max = maximum, SD = standard deviation

41. US Conclusions • Ossification stage classification was possible in all cases with normally developed clavicles. • The age intervals observed are consistent with the known data from CR and CT studies. • The results should be confirmed in a larger number of cases. • Evaluation of clavicular ossification by ultrasound could be a rapid and economic radiation-free imaging procedure for forensic age estimations.

42. Summary • To check whether an individual has completed the 18th year of life it is necessary to assess the stage of clavicular ossification. • An evaluation of the ossification stage is possible with CR, CT, MRI and US. • In CR examinations images obtained in three planes (one p.a., two anterior oblique) should be used. • The slice thickness in CT examinations should be 1 mm. • For MR and US examinations reference studies with large case numbers are required.