THU0704 A new assessment tool for ulnar drift in patients with rheumatoid arthritis using pathophysiological parameters of the metacarpophalangeal joint

Background Ulnar drift (UD) in rheumatoid arthritis (RA) is the most common and difficult to manage deformity in the rheumatoid hand; it is reported that 44% of patients develop UD within the first 10 years. Nevertheless, the assessment of UD is challenging; the Fearnley classification method, first reported in 1951, is still used for evaluation. However, it is sometimes difficult to determine the best surgical procedure simply based on the Fearnley classification, which only evaluates reducibility. Therefore, we have been using both the Fearnley classification as a ‘gold standard’ and an original scoring method that enables us to easily treat the deteriorated condition contributing to UD. Objectives To establish and verify a new assessment tool for UD in rheumatoid hand. Methods We established an observational cohort of 67 patients (134 rheumatoid hands) beginning in 2004, among the RA outpatients who had any apparent finger deformity in either hand. Fifty-two patients (100 hands) had follow-up in 2009, and thirty-seven patients (63 hands) completed follow-up in 2015. For evaluation of UD, we used both the Fearnley classification as a ‘gold standard’ and an original scoring method which assesses four parameters of the metacarpophalangeal joint. Cluster analysis using UD parameters divided hands into groups. For functional assessment, we used the modified Kapandji index (MKI). The MKI enables us to assess unilateral hand functional mobility within a few minutes. Changes in UD over time, correlation of the Fearnley stage and cluster with MKI, and reliability of the parameters with clustering were analysed. Results The 10 year follow-up rate was 55.2%, and UD increased and worsened over time (p Conclusions Our UD evaluation method is quite simple but is closely related to function. Additionally, it enables dividing UD hands into five stages. Thus, our assessment should be beneficial compared to the Fearnley classification in considering treatments of UD. Acknowledgements The authors thank all the researchers involoved in this 10 year observational study. Disclosure of Interest None declared