Joint Ultrasound Evaluation of Asymptomatic Rheumatic Feet

Rheumatoid Arthritis Group

RA with at least one year since diagnosis, asymptomatic feet, and age between 18 and 65 years

Control group

Absence of known osteoarticular disease

Presence of synovial effusion and/or synovial hypertrophy

Ultrasound evaluation - quantitative measurement considered the distance between the joint capsule and subchondral bone of the joints studied (talocrural, talocalcaneal (medial, lateral and posterior windows); dorsal face of calcaneocuboid, talonavicular, medial naviculocuneiform, 5th tarsometatarsal and metatarsophalangeal (MTP) (dorsal and volar faces of 1st to 5th MTP joints and lateral face of 1st and 5th MTP joints). A modified score was used for the semi-quantitative measurement, ranging from 0 to 3: 0-no synovial thickening; 1-minimal synovial thickening in joint recess; 2-synovial thickening in entire joint recess causing bulging of joint capsule; and 3-synovial thickening in joint recess with bulging of joint capsule and extending to at least one bone diaphysis. "Presence of synovitis" was defined as synovial hypertrophy of at least Grade 1 in the semi-quantitative analysis (gray scale - ultrasound)

Presence of bone erosion

defined based on the preliminary OMERACT criteria: intra-articular discontinuity of the bone surface observed on two perpendicular planes. A previously established semi-quantitative score (0-3) was employed: 0-uniform bone surface; 1-irregular bone surface; 2-bone surface defect on two planes; 3-bone defect causing extensive bone destruction. The "presence of erosion" was defined as the presence of at least Grade 2 erosion.

Radiographic evaluation

A blinded radiologist analysed the presence of erosion in each joint studied. For such, ankle (AP and profile) and foot (AP and profile with load) radiographs were taken.

Intraobserver and interobserver agreement

The patients with RA were submitted to clinical and ultrasound evaluations of the feet and ankles on the same day. The ultrasound measurements intraobserver/interobserver agreement was performed on the talocrural, talonavicular and 5th MTP joints, using 20% of the sample. For this, the ultrasound exams were performed by another rheumatologist.

Presence of synovial blood flow

The presence of Power Doppler (PD) signals was evaluated in the bone margins, joint spaces, and peri-articular tissues (frequency of 8 MHz and pulse repetition rate of 750 MHz). A semi-quantitative score (0-3) was employed[14]: 0-no signal; 1-minimal signal, presence of simple vessels; 2-moderate signal, presence of confluent vessels with signal in less than 50% of the area evaluated; 3-intense signal (more than 50% of area evaluated). "Active synovitis" or "presence of PD signal" was defined as the presence of intra-articular synovitis with a positive PD signal (at least Grade 1).