3D freehand ultrasound to estimate the glenohumeral rotation centre

Imaging techniques such as magnetic resonance imaging or scanner could allow the estimation of the glenohumeral rotation centre (GHRC) by approximating the humeral head to a sphere using sphere fitting methods. However, it is not easy to include these data with those obtained by a motion analysis system. On the other hand, 2D ultrasound (2D-US) scanning is a wide, non-invasive and less expensive system. Moreover, 3D freehand ultrasound (3D-US) involving combination of US scanning and 3D motion analysis provides a direct in vivo measurement of anatomical landmarks. The 3D-US has already been used simultaneously in the motion analysis laboratory for locating the hip joint centre (Peters et al. 2010). However, no validation of the estimation of GHRC has been carried out using 3D-US. Contrary to lateral and medial epicondyle, which can be palpated and consequently adapted to each subject, GHRC is usually estimated with predictive or functional methods. Although the predictive methods calculate the centre of rotation (CoR) from empirical relationships between specific anatomical landmarks, the functional methods compute the CoR from the relative motion of adjacent body segments and are reported as accurate. The objective of this study was to validate the use of 3D-US for estimating GHRC in comparison with functional methods and medical imaging.