Femoral Osteosynthesis in Black Capuchin Monkey (Sapajus nigritus) using Locking Plate

Background: Locking bone plates for internal fixation are characterized by plates with a locknut by screwing in a threaded chamber. The increased stability associated with less vascular lesion contribute to the lower risk of complications and makes the locking bone plates especially interesting in fracture management of wild animals to be reintroduced into nature.The aim of this report is to describe the case of a black capuchin monkey with a femoral fracture, submitted to internal fixation using locking plate, with a satisfactory postoperative evolution, characterized by the bone consolidation and full recovery of the function of the member.Case: An exemplar of an adult male black capuchin monkey (Sapajus nigritus) with 4.2 kg of body weight was presented due to a comminuted, diaphyseal fracture of the left femur. The animal was then submitted to internal fixation of the femoral fracture using a 2.0 mm locking plate with 11 holes. For the internal fixation, the plate was contoured and positioned on the lateral surface of the bone. In addition, four locking screws were inserted through both cortices in the proximal bone segment, while other three locking screws were inserted in the distal bone segment. Two of the distal locking screws were inserted through both bone cortices, while one of them were inserted through only one bone cortical. The animal showedcomplete functional recovery of the left hind limb at 30 days postoperatively. Despite this, it was visualized at the radiographic examination a partial release of the plate from the distal bone segment. Due to this, the animal was submitted to another surgical intervention to replace the distal locking screws by bicortical locking screws. The animal showed hind limb weight support at the second day postoperatively. The complete functional recovery of the left hind limb, however, was verified at 26 days postoperatively. In this moment, it was performed a new radiographic examination, which allowed the visualization of bone consolidation, and the animal was reintroduced into its natural habitat.Discussion: The choice of the bone plate may play a fundamental role in the bone healing process. Among many bone plates configuration, locking plates are highlighted, as they offer greater angular stability to the fracture and result in less injuring periosteum and blood vessels. In addition, other methods for internal fixation are related to numerous postoperative complications. Despite the low rate of complications of the locking system, in the present case, it was visualized the partial release of the plate from the distal bone segment, which is probably related to the higher concentration of load near the sniffle joint, and the early release of one monocortical screw. The use of monocortical screws is permissible whenproperly locked in the threaded chambers of the plate. In the present case, however, it is believed that the early release of the distal monocortical screw is probably related to the incompletely screw head locked in the threaded chamber of the plate. Therefore, the use of bicortical screws should be preferred even using locking systems, especially in anatomical regions subjected to a higher concentration of load, as near the sniffle joint. In addition, it is concluded that the locking plate maybe a viable option for the treatment of long bone fractures in wild animals, in particular femoral fractures of specimens of black capuchin monkey (Sapajus nigritus).Keywords: wild animals, internal fixation, fracture

The Use of a Locking Plate for the Treatment of Femoral Diaphyseal Fracture in Giant Anteaters (Myrmecophaga tridactyla)

Background: The giant anteater is considered a species vulnerable to trauma due to being slow and, therefore, vulnerable to long bone fractures, such as femoral fracture. Locking plates have the potential to restore and maintain fractured bone stability, as well as reduce damage to the vascular supply. This study aims at reporting cases of two giant anteaters subjected to femoral osteosynthesis using locking plates. Cases:Two giant anteaters presenting non-weight bearing lameness on the right pelvic limbs were evaluated, diagnosed with femoral fracture of unknown etiology and submitted to osteosynthesis. A clinical evaluation was performed under chemical restraint for the adult animal and physical restraint for the young one. Crepitation and swelling in the right femur topography led to a radiographic examination, which showed a complete and transverse diaphyseal fracture of the right femur in both cases. The first one was an adult male and was subjected to osteosynthesis of the right femur using a locking plate. Once anesthetized, the animal was placed in left lateral recumbency, and the right pelvic limb was clipped and sterilized. A craniolateral incision was made to expose the femoral diaphysis. A large amount of fibrous-looking tissue was found and removed. Subsequently, the fracture was reduced and the locking plate system was positioned on the craniolateral side of the femur. An osteotomy of the femoral trochanteric crest was required to position the implant. The overlying fascia lata was closed using monofilament suture in a simple continuous pattern. The closure of the subcutaneous tissue and skin was performed using a Cushing pattern and simple interrupted pattern, respectively. Immediate postoperative radiographic examinations showed fracture reduction and bone axis alignment, with a properly positioned implant. The surgical wound was cleaned daily with 0.5% aqueous chlorhexidine solution. Seven days after surgery, the animal had a partial dehiscence at the suture site, with bone and plate exposure. Wound healing by second intention was initiated. At 127 days after surgery, a radiographic examination showed periosteal bone proliferation in the middle third of the right femur and that the bone implants were well-positioned. The second case was of a young 3.68 kg female anteater. The surgery was performed as described for the adult one, but there was no fibrosis at the fracture site and the osteotomy of the femoral trochanteric crest was not required. Closure of the fascia lata, subcutaneous tissue, and skin was performed as in Case 1. An immediate postoperative radiographic examination showed fracture reduction, bone axis alignment, and a properly positioned implant. The surgical wound was cleaned daily with 0.5% aqueous chlorhexidine solution. On the day of the surgery, the animal could already bear weight on its right pelvic limb, presenting discrete lameness with gradual improvement. Twenty-three days after surgery, a radiographic examination showed moderate periosteal bone proliferation in the middle third of the right femur. The bone implant was still well-positioned and bone healing was achieved around the 40th post-operative day.Discussion:The cases are very similar, but the younger anteater's femoral trochanteric crest didn't prevent positioning the plate. The fibrosis observed on the adult specimen is indicative of a chronic fracture, which may explain, in conjunction with the post-surgical complications, the longer time required for bone healing in the adult animal. Even so, both animals recovered fully and it's safe to deduce that the locking plate is an adequate option for internal fixation in transverse diaphyseal femoral fractures in both adult and young giant anteaters