Passive motion of the elbow joint.

A previously unreported method of measuring three-dimensional motion of joints, applied to two elbows obtained post mortem, showed that during flexion there is a continuous and linear change in the carrying angle, the forearm going into varus angulation as elbow flexion progresses. In addition, internal axial rotation of the forearm occurs near the beginning and external axial rotation, toward the end of flexion. With the elbow extended, the ulna shows little tendency to deviate laterally or to rotate axially during pronation and supination. The axis of rotation during elbow flexion lies approximately at the center of the trochlea.