Objective: Erosive osteoarthritis (OA) (EOA) is considered an aggressive form of primary OA that is defined radiographically by intra-articular erosions of the inter-phalangeal joints of the hand and characteristic deformities. The aim of the present study was the sonographic investigation of hand small joints in patients with EOA and comparison of the imaging findings with conventional radiography (CR).
Method: Twenty-two patients (20 women, mean age 62.5 years) with clinical and radiographic diagnosis of EOA formed our study group. A total of 660 joints were assessed by both radiographs and ultrasound (US). US and plain films were evaluated by two different physicians on a blinded fashion. Erosions, osteophytes and deformities were evaluated by both US and plain films. Synovial thickening, effusion, and power Doppler signal indicative of abnormal vascularity were recorded in each joint during US scanning.
Results: Erosions were detected in 231/660 (35%) small joints by US and in 115/660 (17.4%) small joints by conventional radiographs (P<0.05). Osteophytes were detected in 360/660 (54.5%) small joints by US, and in 310/660 (47.0%) small joints by conventional radiographs (P<0.05). Thickened synovium was detected in 19 of 22 patients and increased intra-articular power Doppler signal, indicative of active inflammation, was detected in 18 of 22 patients. Thickened synovium was found in 159/660 (24.1%), effusion in 119/660 (18%) and increased power Doppler in 148/660 (22.4%) small joints. Intra-observer kappa value for agreement regarding US was 0.81 and plain films 0.86. In 31 instances extensive finger tenosynovitis was also evident.
Conclusion: In patients with EOA, US is a reliable and a more sensitive imaging modality than CR in detecting erosions and osteophytes. US detects inflammatory changes in small hand joints in the vast majority of patients with EOA and suggests that current treatment modalities are inadequate treatment for this disease.