Indications of inflammation visualized by ultrasound in osteoarthritis of the knee

Ultrasound examination of a group of patients with osteoarthritis (OA) of the knee for signs of inflammation.

71 knees in 71 patients with osteoarthritis of the knee were examined with high-resolution gray-scale ultrasound combined with color and spectral Doppler. The medial, lateral, and antero-superior compartments were examined. Hyperemia was identified as presence of color Doppler signals in the synovial membrane. Low resistance flow was defined as a resistive index < 0.80 on spectral Doppler.

Synovial thickening was found in all knees; fluid in 61 patients; and hyperemia (color Doppler activity) in 51 patients. Of these, 44 had arterial flow on spectral Doppler - 36 with a low resistance flow. When present, fluid and color Doppler activity was found in all three compartments, but with uneven distribution.

The finding in the majority of cases of both effusions on B-mode US and Doppler activity confirms that there is a varying degree of inflammation in knee OA as diagnosed by the ACR criteria.