Sonography of a rupture of the tendon of the extensor pollicis longus muscle: initial clinical experience and correlation with findings at cadaveric dissection.

OBJECTIVE: The objectives of our study were to report our initial clinical experience with sonography of the wrist for diagnosing a proximal rupture of the tendon of the extensor pollicis longus (EPL) muscle and to perform sonographic-anatomic correlation of the EPL tendon.

MATERIALS AND METHODS: Clinical and imaging files of five patients who underwent sonography and subsequent open wrist surgery were reviewed retrospectively. Imaging was performed by four radiologists experienced in musculoskeletal sonography. Tendon retraction was evaluated on sonography and at surgery. In cadavers, sonography was performed in concert by two musculoskeletal radiologists during progressive stages of dissection of four embalmed specimens. One specimen was sliced in the transverse plane.

RESULTS: In cadavers, the EPL tendon was located on or adjacent to Lister's tubercle and extended to the base of the thumb. The EPL tendon crossed over the extensor carpi radialis tendons where it exhibited a flattened aspect. In the five patients in the study, a tubular-shaped hypoechoic area was evident at the position of the ruptured EPL tendon on sonograms. At surgery, this area corresponded to fluid, hemorrhage, and scar tissue in the EPL tendon sheath. The assessment of tendon retraction on sonography correlated with findings at surgery.

CONCLUSION: Sonography may aid in diagnosing a rupture of the EPL tendon and in the preoperative assessment of gap size and position of the retracted tendon ends. A characteristic tubular hypoechoic area may be seen crossing over the extensor carpi radialis tendons.