Comprehensive radiographic grading system and clinical outcomes of canine tibial avulsion fractures in dogs

The tibial apophysis is a separate center of ossification in the proximal tibia of skeletally immature dogs. Because it is made of cartilage during development, it is prone to fractures (avulsions) and other tensile-related injuries. One prior veterinary study proposed a classification system for proximal tibial apophyseal fractures, but this study did not include fractures that involved the proximal tibial physis or metaphysis, which have been described in human classification systems. The objectives of the study reported here were (1) to characterize and establish a radiographic grading system of proximal tibial apophyseal fractures in dogs, (2) to investigate the intra- and interobserver agreements of the proposed grading system, and (3) to identify associations between fracture types and patient signalment, surgical fixation, and clinical outcomes. This is a retrospective and observational study where images were assessed twice in a randomized order at least two weeks apart by three observers. The most frequent fracture configurations were type 1 (33/49, 67.3%) and type 5 (13/49, 26.5%), followed by type 4 (2/49, 4%) and type 2 (1/49, 2%). A fracture configuration type 3 was not identified. Dogs with a concurrent fibular fracture were associated with type 4 and 5 tibial avulsion fractures (P < .01). The intraobserver agreement for observers 1 and 2 was kappa ≥0.88, and for observer 3, kappa = 0.63. In conclusion, this study introduces an enhanced classification system for tibial apophyseal fractures in dogs, demonstrating substantial to moderate intraobserver reliability and moderate to modest interobserver agreement.