Prevalence of joint effusion on ultrasonography in subjects with painful knee osteoarthritis
| Ultrasonographic joint effusion* | p Value† | |||
|---|---|---|---|---|
| Absent | Present | |||
| *Joint effusion was defined as present if depth ⩾4 mm; †p values refer to comparisons between subgroups with or without joint effusion. (Student’s t test for quantitative variables and χ2 test for qualitative variables); ‡missing data for one patient. | ||||
| Subjects, No (%)‡ | 338 (56.4) | 261 (43.6) | ||
| Maximal effusion depth (mm) | <0.0001 | |||
| Mean (SD) | 1.3 (1.4) | 7.5 (5) | ||
| Median (range) | 1.2 (0–4) | 6.3 (4–71) | ||
| Synovial thickness (mm) | <0.0001 | |||
| Mean (SD) | 1.1 (1.5) | 3.3 (2.9) | ||
| Median (range) | 0.6 (0–10.2) | 2.9 (0–29) | ||
| Appearance of synovial tissue, No (%) | <0.0001 | |||
| Normal | 231 (68.3) | 47 (18.0) | ||
| Nodular | 34 (10.1) | 97 (37.2) | ||
| Diffuse | 73 (21.6) | 117 (44.8) | ||