A radiographic projection for the assessment of the equine paracondylar process

Abstract

Background: The paracondylar process is of clinical interest due to its proximity to ana- tomical structures involved in vital functions. There are limited reports describing ab- normalities affecting the paracondylar process (PCP), with traumatic fractures being the most prevalent pathology. Affected horses can present with a variety of signs including headshaking, facial paralysis and/or poor performance. In almost all cases reported in the literature to date, computed tomography has been used to diagnose a PCP fracture. Objectives: The aim of this study was to develop a radiographic technique for imaging the PCP, to determine the optimum radiographic projection angle and trial its use in standing sedated horses. Study design: Cadaveric-simulated clinical case and pilot study conducted in 10 standing sedated horses. Methods: Three tangential radiographs of the left and right paracondylar processes at 5°, 15° and 20° to the transverse plane and 20° to the dorsal plane were obtained in 10 standing sedated horses. Three blinded observers independently ranked each of the three images for clarity of viewing the PCP. The radiographic projection allowed imaging of the ventral portion of the PCP while avoiding superimposition of other osseous structures. A simulated PCP fracture in a cadaver could be recognised using this technique. Results: The highest grades were obtained for radiographs with a 5° angle from the trans- verse plane, and the lowest grades were obtained for a 20° angle. Main limitations: Complex anatomy of the PCP with superimposition of osseous and soft tissue structures. Conclusions: The radiographic technique for the PCP can be safely performed in standing, sedated horses. It is suitable for implementation in general veterinary practice before con- sidering referral for advanced imaging techniques in horses presenting with headshaking or facial paralysis.