A tangential radiographic projection for investigation of the equine temporomandibular joint

Abstract

Objective To (1) describe a tangential radiographic projection of the equine temporomandibular joint (TMJ) and (2) optimize the radiographic angle and determine its use in standing sedated horses. Study Design Descriptive study. Animals Cadaveric equine skulls (n=11); 8 horses with a history of quidding or headshaking. Methods Tangential radiographic projections were taken of a TMJ of a cadaveric skull before and after intra-articular injection of radiographic contrast. Additional tangential radiographic projections were taken after TMJ dissection and placement of a wire along the articular surface of the mandibular condyle. Subsequently, 3 tangential radiographs were taken of both TMJs of 10 skulls at 75°, 70°, and 65° to the dorsal plane (Rt/Le15Cd70D-Le/ RtRVO). Each of the 3 images for each TMJ was ranked by 4 observers who were unaware of the projection angle. Interobserver variation was calculated using a Friedman analysis of variance and significance of the most prevalent angle with a 1-sample repeated measures test. Tangential radiographic projections of both TMJs were then taken of 8 standing sedated horses. Results Tangential radiographic projections allowed the lateral half of the TMJ to be viewed without superimposition of other structures and the anatomic orientation was determined. A 70° projection to the dorsal plane was ranked as significantly better than other views (P