Table 1 MRI Assessment Criteria

Cartilage

Two step process for each joint surface:

Cartilage signal summarized as:

   1. Grade degree of cartilage damage:

0-None = normal

0 = Normal

1-Mild = heterogeneity or fraying

1 = Increased signal heterogeneity without surface disruption

2-Moderate = fissuring or thinning < 50%

2 = Fraying (superficial only)

3-Severe = thinning > 50% or full thickness

3 = Fissuring (full thickness lesions <1 mm in width)

Lesion size summarized as:

4 = Thinning <50% cartilage thickness

0-None = normal

5 = Thinning >50% cartilage thickness

1-Mild = < 1 cm

6 = Full thickness cartilage loss

2-Moderate = 1-2 cm

   2. Score greatest diameter of greatest severity lesion

3-Severe = > 2 cm

0 = Normal

Cartilage signal and lesion size scores summed over 17 regions to give hypothetical range 0-102.

1 = <1 cm

None = 0

2 = 1-2 cm

Mild = 1-30

3 = 2-3 cm

Moderate = 30-60

4 = >3 cm

Severe = > 60

Osteophytes

Two step process for each joint compartment:

Compartmental scores (medial, lateral, patellofemoral) were summed for the whole knee. The possible score range was 0-9. Final assessment of osteophytosis:

   1. Grade individual osteophytes according to the size of the greatest dimension:

None = 0

0 = <1 mm

Mild = 1-3

1 = 1-2 mm

Moderate = 4-5

2 = 2-5 mm

Severe = 6+

3 = >5 mm

   2. Sum scores of all individual osteophytes to give compartmental score:

0 = normal individual sum 0

1 = mild individual sum 1-2

2 = moderate individual sum 3-4

3 = severe individual sum >4

Bone Marrow Lesions

Greatest diameter of each lesion recorded for both femoral and tibial surfaces as well as the patellofemoral compartment:

Scores for patellofemoral compartment and femoral and tibial surfaces were summed. The possible score range was 0-15. Final assessment of bone marrow lesions:

0 = None

None = 0

1 = Mild (<0.5 cm)

Mild = 1-3

2 = Moderate (0.5-1.5 cm)

Moderate = 4-5

3 = Severe (>1.5 cm)

Severe = 6+

Effusion

Greatest diameter of the effusion perpendicular to the long-axis of the leg:

Effusion was recorded as a single score for the whole knee. No changes were made for final analysis.

0 = None (0.0-0.5 cm fluid)

1 = Mild (0.5 -- 1.0 cm fluid)

2 = Moderate (1.0 -- 2.0 cm fluid)

3 = Severe (>2.0 cm fluid)

Synovitis

Assessed by counting the number of thickened villi seen on T2-weighted sequences

Synovitis was recorded as a single score for the whole knee. No changes were made for final analysis.

0 = None (<5 villi seen, all normal thickness)

1 = Mild (6-10 villi seen, some thickened)

2 = Moderate (11-15 villi seen, mostly thickened)

3 = Severe (> 15 villi seen, marked thickening)

Subchondral Sclerosis

For each compartment:

Final score determined by number of the 3 knee compartments with evidence of sclerotic change

0 = Absent

0 = Absent

1 = Present

1 = Mild

2 = Moderate

3 = Severe