The EPB tendon runs through the first extensor compartment alongside APL, inserting on the thumb proximal phalanx (unlike APL which inserts on the metacarpal). It is in a separate subcompartment in 70% of individuals — failure to release this subcompartment in de Quervain's surgery produces incomplete relief. The EPB-APL crossing marks the radial border of the anatomical snuffbox and the dorsal boundary of the first compartment.
Thumb MCP joint extension; thumb radial abduction assistance
Finkelstein's test (passive ulnar deviation of the wrist with the thumb in the palm) tightens the APL and EPB tendons over the radial styloid, producing the characteristic pain of de Quervain's. The EPB subcompartment is identified in surgery by retracting the released APL slips and looking for a separate sheath containing the EPB.
Separate EPB subcompartment causing failed de Quervain's release — identified at revision surgery by retraction of APL to expose the separate EPB sheath.
This website uses cookies to enhance your experience. Some are essential for site functionality, while others help us analyze and improve your usage experience. Please review your options and make your choice.
If you are under 16 years old, please ensure that you have received consent from your parent or guardian for any non-essential cookies.
Your privacy is important to us. You can adjust your cookie settings at any time. For more information about how we use data, please read our privacy policy. You may change your preferences at any time by clicking on the settings button below.
Note that if you choose to disable some types of cookies, it may impact your experience of the site and the services we are able to offer.
Some required resources have been blocked, which can affect third-party services and may cause the site to not function properly.
This website uses cookies to enhance your browsing experience and ensure the site functions properly. By continuing to use this site, you acknowledge and accept our use of cookies.
