Variations of anatomy on MRI of the first extensor compartment of the wrist and association with DeQuervain tenosynovitis.

Abstract

To study anatomical variations on MRI of the first extensor compartment of the wrist in DeQuervain tenosynovitis (DQT). A retrospective search for DQT patients yielded 47 subjects (51 ± 15years, 36 female, 11 male). The age-matched control group (normal first extensor compartment) was 49 ± 15years (29 female, 18 male). Two independent readers reviewed: the number of abductor pollicis longus (APL) tendon slips, tendon sheath septations (compartmentalization), and APL and EPB cross-sectional area (CSA) at the radial styloid. A tendon slip was defined as a discrete structure for ≥5 contiguous slices with its own insertion. The distribution of APL tendon slips was different for the DQT and control groups (Reader 1/Reader 2: P = 0.0001 and 0.001). The most common arrangement for both groups was two APL tendon slips. One tendon slip was less common (P = 0.03 and 0.1) and compartmentalization was more common (P = 0.003; < 0.0001) for the DQT group than the control group. There was no difference in tendon slip insertions on one or multiple bones (P = 0.1; 0.7). APL and EPB compartment CSAs were also higher for the DQT group (combined first extensor compartment area: 21.3 ± 7.6mm2; 21.0 ± 7.1) than the control group (17.2 ± 3.8; 17.1 ± 3.9) (P = 0.002; 0.002). We found a statistically significantly increased proportion of supernumerary tendon slips and compartmentalization of the first extensor compartment in patients with DQT and greater CSA of the first extensor compartment at the radial styloid, consistent with previous anatomical, surgical, and ultrasound studies.