Authors: Jonathan Zember Zehava Rosenberg Ignacio Rossi Chimere MbaJones Jenny Bencardino
Publish Date: 2016/04/23
Volume: 45, Issue: 8, Pages: 1089-1095
Abstract
Fluid along the frondiform ligament the sinus tarsi stem of the inferior extensor retinaculum IER can approximate the extensor digitorum longus EDL at times simulating tenosynovitis Our purpose based on MRI and cadaveric studies was to further evaluate this scantly described phenomenon to identify associated findings and to alert the radiologists to the potential pitfall of over diagnosing EDL tenosynovitisTwo musculoskeletal radiologists retrospectively reviewed the radiology reports and MRI studies of 258 ankle MRI exams performed at our institution for fluid along the frondiform ligament extending toward the EDL No patient had EDL pathology clinically MRI was performed in two cadaveric ankles following injection of the sinus tarsi and EDL tendon sheath under ultrasound guidanceAltogether 31 MRIs demonstrated fluid extending from the sinus tarsi along the frondiform ligament toward the EDL In 30 cases 97 the fluid partially surrounded the tendon without tendon sheath distension Based on the radiology reports in 11 of the 31 cases 35 the fluid was misinterpreted as abnormal Most common associated findings included ligamentous injury posterior tibial tendon PTT tear flatfoot and osteoarthrosis In the cadavers fluid extended along the frondiform ligament toward the EDL after sinus tarsi injection there was no communication between EDL tendon sheath and the sinus tarsiFluid within the sinus tarsi can extend along the frondiform ligament and partially surround the EDL manifesting as pseudotenosynovitis This phenomenon often seen with ligamentous tears or PTT dysfunction should not be misdiagnosed as true pathology of the EDL
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