Post‐operative rupture of manica flexoria and digital flexor tendon sheath wall after annular ligament desmotomy

Summary A 23‐year‐old Cob Cross gelding presented with right hind lameness and moderate effusion of the right digital flexor tendon sheath (DFTS). Tenoscopy revealed a small tear at the lateral margin of the superficial digital flexor tendon (SDFT), extending to the distal portion of the manica flexoria, which was intact and did not require removal. A plantar annular ligament desmotomy was performed and the SDFT tear was debrided. At examination 8 weeks post‐operatively, the horse was sound at a trot and returned to exercise. Eleven weeks post‐surgery the horse presented with an acute onset right hindlimb lameness. Clinical examination revealed severe effusion of the proximal DFTS and swelling extending proximally over the lateral metatarsus. Ultrasonography identified severe effusion of the DFTS with a poorly demarcated fluid swelling extending over the proximal lateral metatarsus and increased space between the SDFT and the deep digital flexor tendon (DDFT) on the nonweightbearing view. Contrast tenography confirmed a large communication between the DFTS and the lateral metatarsal swelling suggestive of a complete rupture of the proximal DFTS. The outline of the manica flexoria was not present, suggestive of a tear. Imaging findings were confirmed via tenoscopy. This case report describes an unusual complication following tenoscopy and plantar annular ligament desmotomy including complete rupture of the DFTS wall and tearing of the manica flexoria. Despite complications the horse made a full recovery.