Abstract
Purpose: Anomalies of the first extensor compartment are widely present in patients presenting with De Quervain’s tenosynovitis (DQT) and require surgical release of the wrist tendons. The aim of this study was to test the hypothesis that such patients exhibit significantly more anatomical alterations in the first extensor compartment, the abductor pollicis longus (APL) tendons and the extensor pollicis brevis (EPB) tendons in comparison with the general population using cadavers.
Methods: A cross-sectional study was conducted during the period January 2013 to May 2014 in which anatomical variations identified in the first extensor compartments of the wrists of 101 DQT patients who had undergone tenolysis were compared with those detected in the wrists of 65 cadavers without DQT determination.
Results: The occurrence of septation in the first extensor compartment was observed in 62.4% of the DQT group (64/101). Supernumerary APL tendons were present in 86.1% of DQT patients (87/101), whereas double EPB tendons occurred in seven patients. In one patient, the EPB tendon was absent. In the cadaveric group, 21.5% (14/65) of the anatomical specimens exhibited double tunnel in the first extensor compartment, while supernumerary APL tendons occurred in 52.3% (34/65) of the wrists. No anatomical variations in the EPB tendon were observed in the cadaveric group.
Conclusion: The predominance of the septated first extensor compartment and the presence of supernumerary APL tendons observed in the DQT group indicated that these anatomical variations may be associated with the syndrome. Such anomalies tend to be less common in the general population and are, presumably, asymptomatic.
Clinical relevance: As septation of the first extensor compartment and multiple APL tendons appears to represent risk factors for the development of DQT, prior knowledge of the frequency of such anomalies may assist surgeons in pre-operative evaluation and perioperative procedures.

Key words: De Quervain disease, tenosynovitis, anatomic variation, wrist