Elbow joint kinematics after excision of the radial head

The contribution of the radial head to elbow joint kinematics was studied in 7 osteoligamentous elbow preparations. During unloaded flexion and extension, radial head excision induced a maximum varus displacement of 1.6° with 20° of joint flexion and a maximum external rotation of 3.2° at 110° of flexion. With application of a 0.75-Nm load, radial head excision induced a maximum laxity of 3.3° at 20° of flexion in forced varus and a maximum laxity of 8.9° at 10° of flexion in forced external rotation. No laxity was observed in forced valgus or internal rotation. The results were independent of the rotation of the forearm. This study indicates that the radial head acts as stabilizer to the elbow joint in forced varus and in forced external rotation. The results suggest that fractures of the radial head cannot be treated by simple excision without altering the basic kinematics of the elbow joint.