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De Quervain Tendons (APL and EPB)

tendines musculi abductoris pollicis longi et extensoris pollicis brevis

De Quervain tenosynovitis involves the tendons of the APL and EPB within the first extensor compartment at the radial styloid. The two tendons share a synovial sheath but may have a fibrous septum between them (present in 30-60% of cases) creating a compartment within a compartment. This septum is the reason simple first compartment release may not fully decompress the EPB, requiring its separate release.

Region: Hand & Wrist

Biomechanics

Function & Actions

Thumb radial abduction (APL) and extension (EPB) through the common first compartment

Clinical Relevance

Clinical Notes

De Quervain's is the most common tendinopathy of the wrist, more common in new mothers (lifting babies), golfers, and racket players. Finkelstein test (ulnar deviation with the thumb clasped in the fist) reproduces pain at the radial styloid. The septum between APL and EPB must be assessed and released separately at surgery. Corticosteroid injection into the first compartment resolves 50-80% of cases without surgery.

Pathology

Common Injuries & Conditions

De Quervain Tenosynovitis

First extensor compartment stenosing tenosynovitis at the radial styloid producing radial wrist pain managed with injection and surgical compartment release including EPB septum release.