34th Annual Scientific Meeting proceedings

Objectives:

The medial digital flexor tendon (MDFT) runs within its own tendon sheath (MDFTS) at the medial aspect of the tarsus. The objective was to investigate the computed tomography (CT) and gross anatomy of the equine MDFTS, as well as the endoscopic anatomy and approach to the MDFTS.  

Methods:

In this experimental study, twelve cadaveric hindlimbs were used. Dissection as well as native and contrast CT were performed to evaluate the anatomy of the MDFTS. Based on those findings, portal locations for endoscopy were determined. Following a pilot phase, six limbs were subjected to standardized endoscopic evaluation using a 0° needle scope.

Results:

Endoscopic entry into the MDFTS was achieved under ultrasonographic guidance distal to the flexor retinaculum, at approximately one third of the distance between the medial malleolus and chestnut. It was possible to enter the MDFTS with both a needle and a conventional arthroscope. However, a complete endoscopic examination was not possible with the conventional scope due to limited maneuverability. Intrasynovial structures identified consistently were the mesotenon in the proximal recess and two synovial folds surrounding the MDFT in the distal portion. The presence of a visible communication between the MDFTS and tarsal sheath varied between the individual horses. One clinical case was presented with septic tenosynovitis due to a penetrating laceration of the MDFTS.

Conclusions:

Endoscopic examination of the MDFTS is feasible by use of a needle scope, and endoscopic lavage of this structure might be indicated for septic tenosynovitis of the MDFTS and/or tarsal sheath.