Table 1.
Demographics of case and control groups at baseline in the present study
| Case knees | Control knees | p-value$ | |
|---|---|---|---|
| Incident knee pain | |||
| N | 157 | 336 | |
| Age, mean (SD) | 62.8 (8.2) | 61.5 (8.1) | 0.095 |
| Women, no. (%) | 108 (69) | 200 (60) | 0.048* |
| White, no. (%) | 137 (87) | 292 (86) | 0.91 |
| BMI, mean (SD) | 29.7 (4.6) | 29.7 (4.5) | 0.99 |
| ROA (K-L grade≥2), no. (%) | 64 (41) | 75 (22) | <.0001* |
| BML (grade≥1)†, (%) | 117 (75) | 225 (67) | 0.090 |
| Cartilage loss (grade≥2)†, (%) | 141 (90) | 271 (81) | 0.011* |
| Meniscal damage (grade≥1)†, (%) | 68 (43) | 99 (30) | 0.0025* |
| Synovitis (grade≥1)†, (%) | 107 (68) | 213 (63) | 0.30 |
| Effusion (grade≥1)†, (%) | 63 (40) | 112 (33) | 0.14 |
| Malalignment** | |||
| Varus (<179°), no. (%) | 71 (45) | 138 (41) | 0.028* |
| Neutral (179–181°), no. (%) | 45 (29) | 139 (41) | |
| Valgus (>181°), no. (%) | 39 (25) | 57 (17) | |
| Incident radiographic OA | |||
| N | 149 | 298 | |
| Age, mean (SD) | 61.7 (7.7) | 61.5 (7.7) | 0.79 |
| Women, % | 92 (62) | 177 (59) | 0.60 |
| White, % | 120 (81) | 258 (86) | 0.11 |
| BMI, mean (SD) | 31.0 (5.4) | 28.9 (4.5) | <.0001* |
| BML (grade≥1)†, (%) | 104 (70) | 174 (58) | 0.056 |
| Cartilage loss (grade≥2)†, (%) | 144 (97) | 232 (78) | <.0001* |
| Meniscal damage (grade≥1)†, (%) | 71 (48) | 55 (18) | <.0001* |
| Synovitis (grade≥1)†, (%) | 72 (48) | 87 (29) | 0.0003* |
| Effusion (grade≥1)†, (%) | 99 (66) | 122 (41) | <.0001* |
| Malalignment | |||
| Varus (<179°), no. (%) | 77 (52) | 129 (43) | 0.059 |
| Neutral(179–181°), no. (%) | 44 (30) | 118 (40) | |
| Valgus (>181°), no. (%) | 25 (17) | 51 (17) | |
Abbreviations: N = total number of knees in case and control groups; SD = standard deviation; BMI = body mass index; ROA = radiographic osteoarthritis; BML = bone marrow lesion; K-L grade = Kellgren-Lawrence grade.
*
denotes statistically significant differences (p<0.05).
†
scored using the Whole Organ Magnetic Resonance Imaging Score (scale 0–3 for BML and synovitis and effusion; scale 0–6 for cartiage; and scale 0–4 for meniscus.)
$
calculated by chi-square test or 2-sample t-test, as appropriate.