Radiographic and computed tomographic configuration of incomplete proximal fractures of the proximal phalanx in horses not used for racing

OBJECTIVE: To characterize the configuration of incomplete proximal fractures of the proximal phalanx (P1) in horses not used for racing and compare radiographic with computed tomography (CT) findings.

STUDY DESIGN: Historical cohort.

ANIMALS: Twenty-four horses with incomplete fractures of P1.

METHODS: Medical records of horses not used for racing diagnosed with an incomplete proximal fracture of P1 based on clinical and radiographic examination and confirmed by CT between 2008 and 2013 were retrieved. Radiographs and CT studies of these horses were analyzed using a subjective grading system and by measuring variables that characterized fracture configuration.

RESULTS: Twenty-four horses were included (20 Warmbloods) with a mean age of 9.5 years and mean body weight of 574 kg. Fourteen forelimbs and 10 hind limbs were affected. Mean duration of lameness was 8.7 weeks. Computed tomography was superior to radiography in both identifying the fracture and determining fracture size and location. On CT, 92% of fractures were located in the mid-sagittal plane. Mean proximodistal length of the fracture was 13 mm. Fractures were frequently not bicortical. Fractures in forelimbs were located significantly more dorsally than fractures in hind limbs. A distinct fracture pattern with 2 subchondral lines running parallel in close proximity to each other was identified in 54% of cases.

CONCLUSION: Incomplete proximal fractures of P1 have significant variation in their configurations, especially their dorsopalmar/-plantar location. Computed tomography examination allowed clear identification of the fracture configurations and was superior to radiography.