Objective To compare inflammation as assessed by ultrasound between patients with the subset erosive hand osteoarthritis (EOA) versus non-EOA.

Methods Consecutive hand osteoarthritis (HOA) patients (fulfilling ACR criteria) were included. Eighteen interphalangeal joints were scored on radiographs using the Verbruggen–Veys anatomical phase score; E and R phases were defined as erosive. Patients were assigned to EOA when at least one joint was erosive. Effusion, synovial thickening and power Doppler signal (PDS) were scored with ultrasound on a 4-point scale. Generalised estimated equation analyses were used to compare ultrasound features between EOA and HOA, and to associate ultrasound features with.anatomical phases; OR with 95% CI were calculated with adjustments for patient effects and confounders.

Results Of 55 HOA patients (mean age 61 years, 86% women) 51% had EOA. In 94 erosive joints, synovial thickening, effusion and PDS were found in 13%, 50% and 15%, respectively; in 896 non-erosive joints in 10%, 26% and 8%, respectively. In summated scores of PDS, effusion was higher in EOA than in non-EOA. Effusion and synovial thickening were more frequent in S, J, E and R phases compared to N phase. PDS was only associated with E phase (OR 5.3, 95% CI 1.3 to 20.5) not with other phases. Non-erosive joints in EOA demonstrated more PDS (OR 3.2, 95% CI 1.6 to 6.4) and effusion (OR 2.2, 95% CI 1.2 to 3.8) in comparison to joints in non-EOA.

Conclusions Inflammatory signs are more frequent in EOA than in non-EOA, not only in erosive joints but also in non-erosive joints, suggesting an underlying systemic cause for erosive evolution.