Palmar/plantar oblique projections improve radiographic detection of fractures of the palmar/plantar processes of the equine distal phalanx.

Radiography is a standard diagnostic test for horses with suspected fractures of the palmar/plantar processes (PP) of the distal phalanx, however published studies evaluating the diagnostic utility for radiography are currently lacking. The objectives of this retrospective, diagnostic case-control study were to determine the sensitivity of radiographs for the detection of PP fractures, and determine the diagnostic utility of the palmar/plantar oblique projections of the PP for the identification of PP fractures compared to standard radiographic series. The medical records of horses undergoing MRI examination were reviewed and 23 horses diagnosed with a PP fracture were included as cases for analysis. Forty-six control horses were selected. Radiographs, including palmar/plantar oblique (palmaro/plantaro50o -proximal 45o -medial(lateral)-dorsodistolateral (medial) oblique (PPrM(L)-DDiL(M)O) projections, and MRI images were assessed independently for the presence or absence of PP fractures and the sensitivity and specificity of radiographs for their detection were calculated, using MRI as the gold-standard. A second, blinded, radiographic evaluation excluding the palmar/plantar oblique views was performed. Twenty-seven PP fractures were identified in the 23 case horses on MRI examination. Twenty-two fractures were identified in 20/23 horses on examination of the full radiographic series (sensitivity and specificity of 81.5% and 100% respectively). Fractures were most frequently identified on the palmar/plantar oblique projections (19/22 fractures), followed by the lateromedial projection. Radiographic assessment excluding the palmar/plantar oblique projections identified 18 PP fractures in 16/23 horses. Careful assessment of a standard radiographic series of the foot will allow identification of PP fractures but palmar/plantar oblique projections will improve the detection of these fractures.