Tenosynovitis is a common feature in rheumatoid arthritis (RA) patients in both hands and feet. The extensor carpi ulnaris (ECU) was seen by Magnetic Resonance Imaging (MRI) to be very commonly involved in RA and in one MRI study ECU involvement in early RA was associated with erosive disease [1,2]. ECU has also been shown by ultrasound (US) to be a frequently involved tendon in RA together with the tibialis posterior (TP) tendon and finger flexors tendons of 2.-4. fingers [3,4].
Though both modalities may be used for detecting tenosynovitis US appear to be more feasible than MRI. The US definition of tenosynovitis was already proposed in 2005 by the OMERACT group  and a recent US study assessed the reliability of detecting inflammatory and destructive tendon abnormalities in patients with RA using an anatomy-based or a free scanning, and independent of scanning technique the overall interobserver reliability for tenosynovitis and tendon damage was found to be excellent both for GS and PD . However, in order to monitor tenosynovitis changes in RA a scoring system is needed and several different systems have been proposed using either descriptive grading, binary grading or semi-quantitative scoring from 0-3 (0=normal, 1=minor, 2=moderate and 3=major amount of tenosynovitis/degree of PD). A recent study explored the reliability of a proposed semi-quantitative scoring system of both grey scale and Doppler and found good reproducibility  which is mandatory for clinical trials.
So far there is no consensus on how many tendons that should be included in a US joint/tendon score for follow-up of RA patients, and this issue needs to be explored together with further studies on the predictive value of tenosynovitis in early RA.
McQueen F, Beckley V, Crabbe J, Robinson E, Yeoman S, Stewart N. Magnetic resonance imaging evidence of tendinopathy in early rheumatoid arthritis predicts tendon rupture at six years. Arthritis Rheum 2005; 52: 744-51.
Lillegraven S, Bøyesen P, Hammer HB, et al. Tenosynovitis of the extensor carpi ulnaris tendon predicts erosive progression in early rheumatoid arthritis. Ann Rheum Dis 2011; 70: 2049-50.
Filippucci E, Gabba A, Di Geso L, Girolimetti R, Salaffi F, Grassi W. Hand Tendon Involvement in Rheumatoid Arthritis: An Ultrasound Study. Semin Arthritis Rheum. 2012 Jun;41(6):752-60
Hammer HB, Kvien TK. Ultrasonography shows significant improvement of wrist and ankle tenosynovitis in rheumatoid arthritis patients treated with adalimumab. Scand J Rheumatol 2011; 40: 178-82.
Wakefield RJ, Balint PV, Szkudlarek M, Filippucci E, Backhaus M, D’Agostino MA, Sanchez EN, Iagnocco A, Schmidt WA, Bruyn GA, Kane D, O’Connor PJ, Manger B, Joshua F, Koski J, Grassi W, Lassere MN, Swen N, Kainberger F, Klauser A, Ostergaard M, Brown AK, Machold KP, Conaghan PG; OMERACT 7 Special Interest Group. Musculoskeletal ultrasound including definitions for ultrasonographic pathology. J Rheumatol. 2005 Dec;32(12):2485-7.
Bruyn GAW, Möller I, Bong D, et al. Reliability testing of tendon disease using two different scanning methods in patients with rheumatoid arthritis. First step towards an ultrasonography scoring index. Rheumatology (Oxford). 2012;51(9):1655-61.
Naredo E, D’Agostino MA, Wakefield RJ, Möller I, Balint PV, Filippucci E, Iagnocco A, Karim Z, Terslev L, Bong DA, Garrido J, Martínez-Hernández D, Bruyn GA; on behalf of the OMERACT Ultrasound Task Force* Reliability of a consensus-based ultrasound score for tenosynovitis in rheumatoid arthritis. Ann Rheum Dis. 2012 Sep 14. [Epub ahead of print]
Disclosure of Interest None Declared