The recent article of O'Reilly et al., “On Representations for Joint Moments using a Joint Coordinate System” [1], opens or re-opens a very interesting debate. Actually, several standardizations for reporting joint angles have been proposed [2–5], promoting the joint coordinate system (JCS). However, for reporting joint moments, no consensus seems to exist.
O'Reilly et al. [1] have efficiently introduced the dual Euler basis that is not always well understood in the biomechanical field. This brings new insights in the discussion on a preferred coordinate system for joint moments: inertial, proximal segment, distal segment or joint coordinate systems, but with two alternative bases (i.e., Euler and dual Euler) for the latter. It is noteworthy that in this long-standing discussion, the basic idea of using the JCS for joint moments was to express the joint angles and moments on the same anatomical axes (i.e.,...
