In vivo elbow biomechanical analysis during flexion: three-dimensional motion analysis using magnetic resonance imaging.

The purpose of this article is to evaluate in vivo 3-dimensional kinematics of the elbow joint during elbow flexion. We studied the ulnohumeral and radiohumeral joint noninvasively in 3 elbows in healthy volunteers using a markerless bone registration algorithm. Magnetic resonance images were acquired in 6 positions of elbow flexion. The inferred contact areas on the ulna against the trochlea tended to occur only on the medial facet of the trochlear notch in all of the elbow positions we tested. The inferred contact areas on the radial head against the capitellum occurred on the central depression of the radial head in all of the tested elbow positions except for 135 degrees flexion, where the anterior rim of the radial head articulates with the capitellum.