Elbow joint kinematics after excision of the radial head

The contribution of the radial head to elbow joint kinematics was studied i n 7 osteoligamentous elbow preparations. During unloaded flexion and extens ion, radial head excision induced a maximum varus displacement of 1.6 degre es with 20 degrees of joint flexion and a maximum external rotation of 3.2 degrees at 110 degrees of flexion. With application of a 0.75-Nm load, radi al head excision induced a maximum laxity of 3.3 degrees at 20 degrees of f lexion in Forced varus and a maximum laxity of 8.9 degrees at 10 degrees of flexion in forced external rotation. No laxity was observed in forced valg us or internal rotation. The results were independent of the rotation of th e forearm. This study indicates that the radial head acts as stabilizer to the elbow joint in forced varus and in forced external rotation. The result s suggest that fractures of the radial head cannot be treated by simple exc ision without altering the basic kinematics of the elbow joint.