Table 1.
Semi-quantitative scoring of radiographic features of knee osteoarthritis. Grading of individual radiographic features (except chondrocalcinosis) was performed using an atlas [29]. KL (Kellgren–Lawrence) grades defined as 0 — no features of OA, 1 — doubtful osteophyte, 2 — definite osteophyte, 3 — definite osteophyte plus narrowing, 4 — osteophyte/narrowing/deformity as in Spector 1993 [34]. OA = osteoarthritis, OP = osteophyte, JSN = joint space narrowing.
| OA feature | Categorical grading | Binary variable (s) |
|---|---|---|
| KL grade (global knee OA) | 0–4 | KL grade ≥ 2 (OA present), KL grade ≥ 3 (moderate OA) |
| Medial compartment osteophyte | 0–3 | Any osteophyte (any OP grade ≥ 1), moderate osteophyte (any OP grade ≥ 2) |
| Lateral compartment osteophyte | 0–3 | |
| Medial JSN | 0–3 | Any JSN (JSN grade ≥ 1), moderate JSN (JSN grade ≥ 2) |
| Lateral JSN | 0–3 | |
| Medial sclerosis | 0–1 | Subchondral sclerosis (grade ≥ 1) |
| Lateral sclerosis | 0–1 | |
| Medial chondrocalcinosis | 0–1 | Chondrocalcinosis (grade ≥ 1) |
| Lateral chondrocalcinosis | 0–1 |