Shoulder bony landmarks location using the EOS® low-dose stereoradiography system: a reproducibility study

Abstract

To investigate the reproducibility of shoulder bony landmarks location using the EOS low-dose stereoradiography system, in order to validate this new tool for the study of gleno-humeral pseudo-kinematics. An inter and intraobserver reproducibility study of shoulder bony landmarks location concerning 22 healthy volunteers. This study concerned the neutral position, arm at rest. Humerus and scapula were modeled with simple geometric shapes using specific software. Those shapes were positioned on A-P and lateral x-rays views. Images analysis of the 22 subjects was carried out three times (n(r) = 3), by two observers (n(o) = 2), for a total of n(tot) = 132 analyses. We obtained a very good reproducibility for the humeral head center and the diaphysis axis with 95% confidence interval (IC95%) inferior to 1.09 mm and 0.41 degrees, respectively. The uncertainty was higher for the lateral and medial epicondyles. Regarding the scapular bony landmarks, we observed a good reproducibility for the tip of the coracoid process, the inferior glenoid rim, and the axillar border with a 95% confidence interval lower than 2.13, 2.91 mm, and 3.67 degrees, respectively. The uncertainty was higher for the most postero-lateral point of the acromion and the superior glenoid rim. Our analysis of the x-rays obtained with the EOS low-dose stereoradiography system assessed the location reliability and reproducibility of specific scapular and humeral bony landmarks. This work opens the way to gleno-humeral pseudo-kinematics analysis using EOS imaging system.