Assessing forefoot bursitis in rheumatoid arthritis: a comprehensive approach with ultrasound, MRI, and baropodometry.

AIM: In rheumatoid arthritis (RA), forefoot bursitis is prevalent, with limited studies comparing ultrasonography (US) and Magnetic Resonance Imaging (MRI). This study aims to evaluate these bursae, providing a comparative analysis of US and MRI, and explore associations with demographic, disease-related factors, pain, clinical examination, and baropodometryin RA patients. MATERIAL AND METHODS: Participants with RA were recruited from the day-hospital clinic. The forefeet were assessed clinically, and the selected foot was examined by US and MRI to evaluate intermetatarsal (IMB) and submetatarsal bursitis (SMB). Baropodometry assessed plantar pressures and contact surfaces. RESULTS: Thirty-five RA patients were enrolled, 85.7% females, mean age 59.2 (11.3) years, mean body mass index (BMI) 26.5 (5.7) kg/m2, median disease duration of 36.0 (16.5-114.0) months, and 34.3% with painful forefoot. A total of 140 intermetatarsal and 175 submetatarsal spaces were evaluated. Agreement between US and MRI was high (PA=97.14%, k=0.801, p<0.001), and interobserver reliability for both modalities was excellent (US: PA=98.73%, k=0.888, p<0.001; MRI: PA=98.41%, k=0.900, p<0.001). IMB was negatively associated with disease duration (the only independent predictor) and linked to clinical signs like the opening toes sign and hammer toe deformity. SMB showed an association with BMI and erosions. Baropodometric analysis indicated no significant differences in plantar pressures for IMB, and larger contact surfaces in SMB regions. CONCLUSIONS: US and MRI are valuable tools for forefoot bursitis evaluation. IMB is associated with disease duration (negative association), the opening toes sign, and hammer toe deformity, while SMB correlates with BMI, erosions, and foot architectural deformity. Baropodometry revealed larger contact surfaces in regions with SMB.

Reasons for discordances between ultrasonography and magnetic resonance imaging in the evaluation of the ankle, hindfoot and heel of the patients with rheumatoid arthritis.

AIM: To compare the ultrasonography (US) performance with magnetic resonance imaging (MRI) in identifying pathology in ankles, hindfeet and heels of rheumatoid arthritis (RA) patients and to evaluate the reasons for discordances between the two imaging methods. MATERIAL AND METHODS: RA patients were enrolled and evaluated using the Clinical Disease Activity Index (CDAI) and the Disease Activity Score 28 with C-reactive Protein (DAS28-CRP). The ankle (tibiotalar joint, tendons), hindfoot (talonavicular, subtalar joints) and heel of the most symptomatic or dominant foot (for the asymptomatic patient)were evaluated by two pairs of examiners using US and contrast-enhanced MRI. RESULTS: Totally, 105 joints, 245 tendons and 35 heels in 35 patients [mean age 59.2±11.25 years old, median disease duration 36 (16.5-114), mean CDAI 19.87±12.7] were evaluated. The interobserver agreements between the two sonographers, and the two radiologists were good and very good (k=0.624-0.940). The overall agreement between US and MRI was very good for subcalcaneal panniculitis (k=0.928, p<0.001), moderate for synovitis (k=0.463, p<0.001) and tenosynovitis (k=0.514, p<0.001), fair for osteophytes (k=0.260, p=0.004), and poor for erosions (k=0.063, p=0.308) and heel's structures. MRI found more erosions, synovitis, osteophytes,tenosynovitis and retrocalcaneal bursitis, but US found more enthesophytes and plantar fasciitis. Many of the discordancesbetween the two imaging techniques have explanations related to the technique itself or definition of the pathologic findings. CONCLUSIONS: US is comparable to MRI for the evaluation of ankle, hindfoot and heel in RA patients and discordances in theinterpretation of the pathological findings/normal structures must be carefully analyzed.