The document describes different grades of ACL tears: Grade I is a low-grade partial tear with over 50% of fibers intact; Grade II is a high-grade partial tear with less than 50% of fibers intact; Grade III is a complete ACL tear with discontinuous or non-visible fibers and an abnormal ligament slope or empty notch sign.

6. 1. Grade I sprain (Low-Grade partial tear)
• Signal around ACL
• The fibres of the ligament are stretched, and
we can see more than 50% of its fibres intact.
2. Grade II sprain (High-Grade partial tear)
• Signal within ACL
• We can see less than 50% of fibres intact.
3. Grade III tear (Complete ACL tear)

7. Grade I sprain
(Low-Grade partial tear)

8. Grade II sprain
(High-Grade partial tear)

9. Grade III tear (Complete ACL tear)
1. Discontinuous fibers
2. Non-visible fibers
3. Abnormal slope of the ligament
4. Empty notch sign

10. Grade III tear
(Complete ACL tear)
Discontinuous fibers

11. Grade III tear
(Complete ACL tear)
Non-visible fibers

12. Grade III tear
(Complete ACL tear)
Abnormal slope of the ligament

13. Grade III tear
(Complete ACL tear)
Abnormal slope of the ligament

14. Grade III tear
(Complete ACL tear)
Abnormal slope of the ligament

15. Grade III tear
(Complete ACL tear)
Abnormal slope of the ligament

18. Grade III tear
(Complete ACL tear)
Empty notch sign

19. Grade III tear
(Complete ACL tear)
Empty notch sign

23. 1. Grade I Sprain
• High Signal superficial to the collateral ligament
• The fibres of the ligament are stretched, and
apparently intact
2. Grade II Sprain (Partial Tear)
• Signal within the collateral ligament with disrupted
and intact fibres
3. Grade III Tear (Complete Tear)

24. Grade I Sprain

25. Grade II Sprain

26. Grade II Sprain

27. Grade II Sprain

28. Grade II Sprain

29. Grade III Sprain

30. Grade III Sprain

45. Sequence Bone Cartilage Fluid
T1 Signal Void Iso Hypo
T2 Signal Void Hypo Bright
PDFS Signal Void Hyper Bright
Gradient Signal Void Hyper Bright

62. Grade MRI finding
I Focal signal intensity changes without contour deformity
(difficult to assess on MRI)
II Focal signal intensity change and contour bulge (partial
thickness)
III Focal signal intensity change, contour irregularities,
cartilage thinning and fluid extension into cartilage (full
thickness)
IV Similar to stage III with defects extending to the cortical
bone (with subchondral bony changes)