de Quervain disease: US identification of anatomic variations in the first extensor compartment with an emphasis on subcompartmentalization.

PURPOSE: To demonstrate the usefulness of ultrasonography (US) in the detection of anatomic variations in the first extensor compartment of the wrist in patients with de Quervain disease. MATERIALS AND METHODS: The institutional review board approved this study protocol and waived the informed consent requirement. Fifteen wrists in 13 women (age range, 41-62 years) in whom de Quervain disease was clinically diagnosed and who underwent surgery for intractable pain were included. A musculoskeletal radiologist performed US before surgery. The absence or presence and extent of subcompartmentalization within the first extensor compartment and the number of abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendon slips were evaluated and recorded. Preoperative US findings were compared with surgical records and photographs. RESULTS: Subcompartmentalization within the first extensor compartment was observed during surgery in 11 of the 15 wrists (73%), including four (27%) that had subcompartmentalization only in the distal portion of this compartment. US was used to identify all 11 wrists showing subcompartmentalization within this compartment (sensitivity, 100%; 95% confidence interval [CI]: 74%, 100%), as well as three of the four wrists with distal incomplete subcompartmentalization. There was one wrist with false-positive distal incomplete subcompartmentalization. US had a positive predictive value in the detection of subcompartmentalization of 73% (95% CI: 47%, 91%). The number of tendon slips in this compartment detected with US was identical to that identified at surgery with one exception. CONCLUSION: US can be used to depict various types of anatomic variations in the first extensor compartment in patients with de Quervain disease.