Endoscopic examination of the tarsal sheath of the lateral digital flexor tendon in horses

This study was designed to develop a reliable technique for endoscopic exam ination of the tarsal sheath of the lateral digital flexor tendon of horses . The anatomy of the tendon sheath and associated structures was studied in detail in cadavers before determining portals for the insertion of an arth roscope into the sheath. Approaches into the sheath through the proximal po uch and through the flexor retinaculum, at the level of the sustentaculum f all, were performed and compared in cadavers. The proximal pouch portal per mitted visualisation only of the proximal half of the sheath, while the app roach through the retinaculum allowed examination of the entire sheath. The normal endoscopic appearance of the tarsal sheath was studied. The endosco pic approach was subsequently used to examine and treat 5 horses with tarsa l sheath tenosynovitis, including 2 cases of chronic, traumatic tenosynovit is and 3 of subacute septic tenosynovitis. Four of these horses had fragmen tation of the sustentaculum fall. The technique allowed adequate examinatio n of the sheath and debridement of adhesions and lesions within the lumen o f the sheath. Fragments dorsal to the medioplantar edge of the sustentaculu m tali could not be visualised endoscopically and had to be removed after w idening of the wound. All 5 horses survived. Follow-up enquiries (8-31 mont hs) revealed that the horses were all reported to be sound. Four were perfo rming at their previous level of activity, 1 was used for hacking. The 2 ca ses presented with chronic tenosynovitis had residual sheath distension wit h no associated loss of function. A prospective study, including longer ter m follow-up investigation, is currently being performed.