Table 2.

Comparison of the effusion area identified by ultrasonography according to the severity of knee osteoarthritis identified by radiography

Effusion area (mm2)	Total N = 254	KLG 2 N = 180	KLG 3 N = 57	KLG 4 N = 17
Average value	49.6 ± 52.4	39.2 ± 40.2	69.5 ± 59.3*	93.0 ± 91.3*
95 % CI	43.1, 56.1	33.3, 45.1	53.8, 85.3	46.0, 140.0

Statistical analysis was by analysis of variance (Tukey post-hoc test); ^* P ≤ 0.01 compared to Kellgren-Lawrence grade (KLG) 2. The effusion area of each knee joint was measured (n = 254 knees). CI confidence interval