Tendon involvement in rheumatoid arthritis of the wrist: MRI findings.

OBJECTIVE: To evaluate the distribution and extent of wrist tendon alterations in patients with active rheumatoid arthritis (RA) using magnetic resonance imaging (MRI). DESIGN AND PATIENTS: Forty-three clinically active RA patients with an illness duration of less than 4 years and no clinical evidence of tendons tears were enrolled in the study. There were 10 men and 33 women, with an average age of 52 years (range 33-63 years). MRI of both wrists, with one exception, was performed at 1.0 T using T1- and T2-weighted sequences (slice thickness 3 mm). Twelve healthy subjects (8 women, 4 men; mean age 31 years) were also evaluated as a control group. Two radiologists reviewed each of four schematic anatomical regions (volar, dorsal, ulnar, radial) for the degree of tendon and tendon sheath alterations using two progressive scales.
RESULTS: In the control group all tendons had homogeneous low signal intensity on all sequences. A small amount of fluid was found in six subjects but the diameter was always less than 1 mm. In the patient group minimal fluid (< 2 mm) was found in 35 (41%) wrists, grade 2 fluid (< 2 > 5 mm) in 26 (31%) and grade 3 fluid (> 5 mm) in 24 (28%). Fifty-nine (69%) of the grade 1 changes were in the volar compartment but grade 2 involvement was evenly distributed. Grade 3 changes were most common in the dorsal compartment and combined grade 2 and 3 in the dorsal and ulnar compartments were 32 (38%) and 25 (30%) compared with 16 (18%) and 17 (20%) respectively in the volar and radial compartments. The tendons were normal (grade 0) in 47 (46%) wrists. A maximum tendon signal change (grade 1) was demonstrated in 28 wrists (32%). When associated with other individual tendons grades this grade was demonstrated in the dorsal compartment in 30 (35%) wrists, in the volar compartment in 12 (14%), in the radial compartment in 17 (20%) and in the ulnar compartment in 26 (30%). A partial tear (grade 2) was detected in 7 (8%) wrists, all involving the dorsal and ulnar compartments; five underwent surgical repair and one proved to have a complete rupture of extensor digitorum. Three (3%) had a grade 3 complete tendon tear: all of these were in extensor tendons. Surgical repair was successful in one case but two ruptured again within 3 months.
CONCLUSIONS: Low grades of peritendinous effusion were more common in the volar compartment whereas moderate and high degrees of tendon sheath fluid collection and/or pannus and signs of tendonitis were more frequent in the dorsal and ulnar tendon sheaths.