The development of a kinematic model of the pro- and supination, that can b
e used to predict the influence of angulations of ulna and radius on the pr
onation and supination is based on the precise knowledge of the pronation a
nd supination movement. We performed two parallel studies for examining the
pronation and supination motion of the human forearm. The first experiment
dealt with MRI-studies on 18 probands (36 examined forearms). As a result
we observed an evasive movement of the ulna during the rotation of 7,14 deg
rees medial.
In order to prove whether the evasive movement was ca used by a rotation of
the humerus or by an evasion in the articulatio humeroulnaris, we carried
out a second experiment, using 30 preparations. The measurement of the pro-
and supination motion with a fixed humerus was expedited using a special e
xperimental setup which guaranteed that the ulna could move freely. In all
cases we found the same magnitude of the evasive motion of the ulna.
Therefore we demonstrated,that the ulna performs an evasive motion during t
he pro- and supination motion of the forearm that influences the kinematic
behavior of the pro- and supination motion significantly.