Long bone fractures i n impala (Aepyceros melampus) : a classifica tion system and review of 55 cases

Abstract

Aim and objective:To introduce and apply a modified-Unger fracture classification in impala, determine the long bone fracture distribution based on 58 long bone fractures, and report the fracture fixation methods used to treat some of the fractures studied. Study design : Retrospective descriptive radiographic study. Sample population: Fifty eight long bone fractures in 55 impala. Materials and methods: This radiographic study evaluated 122 radiographs of 58 long bone fractures in 55 impala. The Unger fracture classification was modified and fracture illustrations for the metacarpal and metatarsal bones added. Each fracture was classified and assigned a four symbol alpha-numeric code using this classification. The long bone fracture distribution, patient signalment, skeletal maturity, fracture associated soft tissue changes, presence of fissure lines, periosteal reaction, fracture displacement, cause of the fracture and treatment were recorded. Results :The overall fracture distribution based on location, found tibial (n=17) fractures to be the most common. Seventy eight percent of the cases had fractures in the diaphysis. The fracture distribution based on complexity was 46% simple, 28% wedge and 26% multi-fragmentary fractures and based on severity was 36% severity 1, 36% severity 2 and 28% severity 3. Fifty seven percent of the fractures affected rams and 43% ewes, with 68% of all cases being skeletally immature. Fifty three percent of cases had open fractures and fissure lines were detected in 34% of fractures. Eighty two percent of all cases had no periosteal reaction associated with the fracture. The average displacement in a cranio-caudal direction was 18 mm, medio-lateral 16 mm and proximo-distal 32 mm. The cause in the majority of fractures was unknown, with some fractures caused by an immobilization dart (n=6). Most patients were treated with external fixation (n=18) only, followed by internal fixation (n=6) or a combination of internal and external fixation methods (n=4). Conclusion :The modified-Unger fracture classification was applicable in classifying 58 long bone fractures in impala, and facilitated determining the long bone fracture distribution. This classification, the determined fracture distribution and the reported fracture fixation methods, should provide a foundation for further advances in veterinary and comparative ungulate, and particularly antelope, orthopaedics and traumatology.