1. JD Craik, R Malina, V Ramasamay & NJ Little

2. Subacromial Impingement & Rotator Cuff Tears 44% to 65% of all shoulder complaints Two main theories: Mechanical (extrinsic) theory Degenerative (intrinsic) theory

3. Anatomical Risk Factors Type I Type II Type III Bigliani Classification

4. Anatomical Risk Factors AH Coracoacromial Arch Height

5. Anatomical Risk Factors AVP Acromion Ventral Projection

6. Anatomical Risk Factors AT Acromion Tilt

7. Acromioglenoid Angle AGA Anatomical Risk Factors

8. CGA Coracoglenoid Angle Anatomical Risk Factors

9. ALP Acromion Lateral Projection Anatomical Risk Factors

10. CLP Coracoid Lateral Projection Anatomical Risk Factors

11. GV Anatomical Risk Factors Glenoid Version

12. GI Glenoid Inclination Anatomical Risk Factors

13. 14 Mya 7 Mya 6 Mya

14. Anatomical risk factors unique or accentuated in human scapulae may play a more direct role in subacromial impingement and rotator cuff tear aetiology. Hypothesis

15. Methods

16. Dry Bone Scapulae 22 human 17 gorilla 13 chimpanzee 12 orangutan Methods

18. Fiji Image J Software Microsoft Excel (Mac 2008)

19. Methods VBL Vertebral Border Length

20. Methods Supraspinatus Area Infraspinatus Area

21. Results Bigliani Classification Type I Type II Type III Bigliani Type I / II / III0 / 8 / 41 / 11 / 14 / 13 / 03 / 17 / 2

22. Results Coracoacromial Arch Height Increased Risk mm

23. Results Acromion Ventral Projection Increased Risk mm

24. Results Acromion Tilt Increased Risk Degrees

25. Results Acromioglenoid Angle Increased Risk Degrees

26. Results Coracoglenoid Angle Increased Risk Degrees

27. Results Acromion Lateral Projection Increased Risk mm

28. Results Coracoid Lateral Projection Increased Risk mm

29. Results Glenoid Version Increased Risk Degrees

30. Results Glenoid Inclination Increased Risk Degrees

31. These anatomical risk factors are not unique to humans! The extrinsic theory is not supported by these results as a primary aetiological factor Therefore:

32. Results Fossa Ratio???

34. This study aimed to determine if any of the risk factors associated with impingement and rotator cuff tears are accentuated in humans The extrinsic theory is not supported by these results as a primary aetiological factor Reduction in Supraspinatus Fossa Size Muscle / tendon insufficiency ? Force vector shift ? Conclusions

35. Thank You