1. Imaging in Osteoarthritis
Dr Matt Chamberlain
Sports & Exercise Medicine Registrar
MP Sports Physicians

2. Imaging in Osteoarthritis
Major focus on knee
Imaging types:
X-ray
MRI
Newer MRI modalities

3. Why image in Osteoarthritis?
Diagnosis
Staging
Prognosis
Efficacy of Treatment
Follow-up

4. X-ray Simplest imaging technique First Line
Can detect OA-associated bony features:
Marginal osteophytes
Subchondral sclerosis
Subchondral cysts.
Joint space width (JSW) - an indirect surrogate of cartilage thickness and meniscal integrity.
Joint space narrowing (JSN) is the key end point currently for interventional studies

5. X-ray Correlations Correlation between x-ray and symptoms is variable:
Knee x-ray correlates with symptoms - 85%
Hand and wrist x-ray correlates with symptoms - 80%
Hip x-ray correlates with symptoms - 75%

6. X-ray Findings Non-uniform narrowing of joint space
Subchondral bony sclerosis
Marginal osteophyte formation
Subchondral Cyst formation
Gross deformity in advanced cases

7. Joint Space Narrowing

8. Marginal Osteophytes

9. Subchondral Sclerosis

10. Subchondral Cysts

11. Gross deformity/Malalignment

12. Kellgren-Lawrence (KL)grading system

13. Progression in Osteoarthritis

14. Progression in Osteoarthritis

15. To weight bear or not to weight bear?
Rosenberg View: 
A weightbearing PA with the knees flexed 45 degrees.
Most sensitive view for tibiofemoral OA
Can be positive if weightbearing AP is normal.

16. Weight bearing knee x-rays

17. Weight bearing ankle x-rays

18. Limitation of x-rays Images bone only (‘whole joint process’)
Gives only indirect measure of chondral thickness/mensical integrity
Insensitive to early change
Insensitive to progression

19. MRI – why image? Not routine clinical initial assessment
Not routine for follow up in OA
Useful in abnormal clinical presentation (i.e. tumour/AVN)
Very sensitive with early presentation of rheumatalogical diseases
Particularly useful in early stage OA
Mechanical intra-articular issues
Visualisation of pathologies not detected on x-ray

20. MRI – why image? Different definitions of OA in X-ray criteria
MRI studies have strongly associated pain with the presence of synovitis and BML (bone marrow lesions)

21. Focal chondral pathology

22. Focal Chondral Pathology

23. Meniscal Pathology

24. Synovitis

25. Bone Marrow Lesions (BMLs)

26. Mechanical Pathology

27. Extra-articular pathology

28. Special mention: Hip OA
Hip – spherical structure
Thin covering of articular cartilage
More difficult assessment than the knee
Other features seen:
Labral changes/hypertrophy
Paralabral cysts
Loose bodies
Dysplasia

29. Special mention: Hip OA

30. Special mention: Hip OA

31. Advances in MRI imaging
Can we see changes in chondral pathology earlier?
Predominantly research tools
Two major areas of advance:
Quantitative articular cartilage analysis
Compositional MRI:
dGEMRIC
T1 rho
T2 mapping

32. Quantitative Articular Cartilage Analysis
High- resolution 3D imaging sequences
Requires segmentation of the hyaline cartilage
Allows measure of tissue dimensions:
Cartilage Volume (VC)
Cartilage Area (AC)
Area of Subchondral Bone (tAB)
Area of denuded Subchondral Bone (dAB)

33. Quantitative Articular Cartilage Analysis

34. Quantitative Articular Cartilage Analysis

35. Quantitative Articular Cartilage Analysis
Interesting research tool
Quantitative nature makes it powerful
Found associations between:
Weight gain and increased cartilage loss
Weight loss and decreased cartilage loss
High BMI/Leptin levels associated with cartilage loss
Systemic bone/subchondral bone density and risk of progression

36. Compositional Imaging
Cartilage consists of:
1-2% Chondrocytes
5-10% Proteoglycans (GAGs)
15-20% Type 2 Collagen
70-80% water

37. dGEMRIC MRI
Assesses early chondral changes through GAG loss prior to macroscopic cartilage loss
Uses intravenous/intra-articular gadolinium that repels GAGs
With Less GAG in cartilage there is more contrast penetration

38. dGEMRIC MRI

39. T2-weighted mapping
Describes the composition of hylaine cartilage on basis of collagen structure and hydration
In healthy cartilage, T2 values increase from deep to superficial
Based on anisotropy of collagen fibers running parallel to subchondral bone
T2 values vary with age and with distance to subchondral bone

40. T2-weighted mapping

41. T2-weighted mapping