Abstract
Objective The aim of this study was to determine the accuracy and repeatability of the shoulder
abduction test and to assess the effect of transection of the medial shoulder support
structures in canine cadavers.
Materials and Methods The shoulder abduction angle was measured by three separate observers, both with
the shoulder extended and at a neutral angle. Shoulder abduction was then measured,
using craniocaudal fluoroscopic images. Arthroscopy was performed in all shoulder
joints, with the medial support structures transected in one shoulder of each dog.
The three observers again measured shoulder abduction angles in all dogs. Shoulder
abduction was measured again using fluoroscopy. Accuracy and repeatability of the
abduction test were assessed using linear mixed models.
Results All three observers had different measured abduction angles when compared with fluoroscopy
(p < 0.01); however, the experienced surgeon had an error of only 2.9°. Inter-observer
repeatability was poor, with all three observers having different abduction measurements
(p < 0.001). Intra-observer repeatability, however, indicated no differences on repeated
measurements (p = 0.26). Placing the shoulder at a neutral standing angle, and transection of support
structures caused an average increase in abduction by 8.2° (p < 0.001) and 4.4° respectively.
Conclusion Significant variation exists between observers performing this test, increased accuracy
seen in the more experienced observer. Shoulder flexion angle can significantly affect
measured abduction angles.
Keywords
shoulder abduction - measurement - dog - instability - fluoroscopy
