Sistema plate-nail para fixação de fratura de fêmur em um lobo-guará (Crysocyon brachyurus)

Abstract

Background: Traumatic causes is the main factor for bone fractures. Femoral fractures are common in dogs and cats and usually require internal fixation for bone healing. However, there is little described about fractures in wild animals. Diaphyseal fractures of long bones generally involve complex surgical procedures for maintaining of the alignment and length of the bone during its consolidation. The maned wolf (Crysocyon brachyurus) is a canid found in the Brazilian cerrado and solitary habit. This species is among those threatened with extinction. This study reports the surgical treatment in a femoral fracture in a maned wolf using an interlocking nail-plate combination.

Case: A young maned wolf, 36 kg intact male, was admitted to the veterinary hospital due to running over. The animal did not weight bear on right pelvic limb. Under anesthesia with ketamina (15 mg/kg) and midazolan (0,3 mg/kg), orthopedic examination was performed. There was severe swelling in the proximal region of the pelvic limb and abnormal mobility in the middle third of the right femur. Radiographic examination showed fragmented and oblique fracture in the right femoral shaft. Surgery for internal fracture fixation was required. The distal segment of the fracture had a fragment with long oblique line, similar to a bevel, and two wires steel cerclage of 1.0 mm were used to stabilize it. The medullary canal of the femur was drilled with a drill 4.5 mm diameter and then went up a rear 8 mm. With the proper instruments, an interlocking nail 8 mm diameter and 195 mm in length was inserted in the medullary canal of the fractured femur. After this procedure, a bone plate was shaped on the lateral surface of the femur. With the aid of the drill guide, proceeded to plate and interlocking nail fixation with screws 3.5 mm in diameter, and the two proximal and two distal screws were bicortical, because these orifices plate coincided with the interlocking nail orifices. Monocortical also two screws were placed in the proximal bone segment to the fracture. Postoperatively, antibiotics and analgesia medication was mixed with the food. After 14 days, the animal showed partial weight bear of the pelvic limb affected, being 30 days after moderate lameness and mild lameness at 60 days. Radiographic examination revealed bone healing of the fracture at 60 days and the animal was transferred to a rehabilitation center for wildlife.

Discussion: The maned wolf is found throughout South America, however, Brazil has the largest number of them in its territory, and is currently considered an extinction animal. Thus, the case shows that the described surgical treatment not only contributed by the animal health, but also to minimize the effects of extinction of the species. The running over is a major cause of mortality among wild canids, which contributes to the low population of the species. This case presents a novelty in treatment of fractures with a new association, using the interlocking nail and bone plate interconnected, giving rise to a new system called plate-nail, which gives high strength and stiffness to bone fixation method. In conclusion, the plate-nail system was effective in providing rapid bone healing in a fragmented fracture of the femur in a maned wolf. The internal fixation system used provided early functional return of the limb pelvic affected, which showed the proper synergy between bone plate and interlocking nail. In addition, there is the possibility of using the plate-nail system for fixation fractures in wild species.