Osteossíntese com haste bloqueada (“interlocking nail”) como tratamento de fratura do terceiro metatarso após artrodese metatarsofângica com haste intramedular modificada em equino / Osteosynthesis with blocked nail (“interlocking nail”) as a treatment for fracture of the third metatarsal after metatarsophalangeal arthrodesis with modified intramedullary nail in equine

ABSTRACT

Background: The metacarpal/metatarsophalangeal joints, as well as the suspensory apparatus, are usually affected by injuries, due to the intense physical demand during sports and great range of motion, predisposing to degenerative processes,trauma and rupture of the suspensory apparatus. In this case, arthrodesis is the main technique indicated. Such surgicaltechniques have a poor prognosis due to post-surgical complications, such as implant infection. Therefore, the study ofprocedures that promote better joint stabilization is important, with reduced surgical time and tissue exposure, decreasingsignificantly the chance of infection and other possible complications.Case A 5-year-old male horse was referred to the hospital with a history of trauma and a lacerating wound in the metatarsalplantar region of the left hindlimb. The animal presented grade IV (I-V) claudication of the left hindlimb with hyperextension of the metatarsophalangeal joint and significant pain on palpation, evidencing the rupture of the superficial, deep digitalflexor tendons and suspensory ligament of the fetlock. The initial surgical treatment was performed using the arthrodesistechnique described by [16]. The intramedullary nail was used with fixation of the plate on the plantar face of the first phalanx together with a single plate fused to the pin, adjusted according to size of the first phalanx, 13 mm thick x 15 cm long,forming an angle between 120º and 140º. Twenty-four h after surgery, there was a simple spiral diaphyseal fracture (typeA), in the middle third of the third metatarsal bone in the region of the proximal end, due to the lever held by the short nailagainst the diaphysis cortex. To treat the complication, an intramedullary 316 L surgical steel rod 13 mm thick x 21 cm longwas used, filling the entire spinal canal. The nail had three holes at the proximal end and two holes at the distal end...