Arthrographic description of the canine carpal joint cavities and its recesses.

Joint effusion is diagnostically important. The canine carpal joint effusion, which is sometimes difficult to detect clinically, has received less attention in diagnostic ultrasound (US) studies. The aim of the present study was to provide a description of the morphological appearance of the canine carpal joint cavities and recesses using US, radiography, helical computed tomography (CT) and three-dimensional volume rendering technique (3D-VRT) images and to prove the applicability of musculoskeletal US for the detection of artificial carpal joint effusion in dogs. The understanding of the characteristics of these structures in normal patients is essential in the diagnosis. Twenty-eight clinically and radiologically unremarkable canine carpal cadavers of different breeds were examined, representative images were selected and anatomical structures were labelled. The canine carpal joint cavities and in particular its recesses had a complex appearance with a basic structure found in all dogs: Antebrachiocarpal joint: dorsoproximal antebrachiocarpal recess, dorsodistal antebrachiocarpal recess, medial antebrachiocarpal recess, lateral antebrachiocarpal recess and five palmar antebrachiocarpal recesses. Middle carpal joint: two dorsal middle carpal recesses, medial common middle carpal and carpometacarpal recess, lateral common middle carpal and carpometacarpal recess, four palmar middle carpal recesses. The carpometacarpal joint had dorsal and palmar funnel-shaped and irregular, finely tubular extensions, the most prominent ran dorsal to metacarpal III, the maximum distal end represented the proximal metacarpal diaphysis. All recesses presented ultrasonographically as a generalized anechogenic to hypoechoic filled continuation of the articular capsule with an indistinct peripheral hypoechogenic to isoechogenic fine capsule, the synovial-connective tissue interface was difficult to identify. The novel results of this study provide the first morphological description of the ultrasonographic, radiographic and computed tomographic arthrographic appearance of the canine carpal joint cavities and recesses with different injection volumes. The canine carpal joint cavities and in particular its recesses had a complex appearance with a basic structure found in all dogs. The applicability of musculoskeletal US to visualize an artificial carpal effusion has been demonstrated. The results of this study, and in particular US, give the practitioner an advantage in visualizing joint effusion and assist in the decision to perform arthrocentesis.