REIDER PART 106

96_Chapter 3 Elbo w and Forearm

an cccentric contraction of the pronator teres usually morc successfully reproduces the patienfs pain. To pro-ducc an cccentric contraction of the pronator muscula-ture, the patienfs forearm is placed in a position of ncutral rotation. The examiner grasps the patienfs hand with both hands. The patient is warned that the examiner is going to attempt to further supinate the patienfs hand. The patient is instructed to resist as forcefully as possible (Fig. 3-54). This maneuver produces an eccentric contraction of the pronator teres and, in most cases, reproduces the pain of flexor-pronator tendinitis.

Stabiuty Testing

Although its bony congruity imparts considerable stabil-ity to the elbow joint, the elbow ligamcnts also fili an important role. Chronić laxity of the elbow ligaments, although not common, can lead to specific instability syndromes.

Valgus Stress Test. The medial (ulnar) collateral liga-ment complex is the most important ligamentous stabi-lizer of the elbow and provides the principal soft tissue resistance to abnormal valgus laxity. The medial collateral ligament complex may be injured along with other struc-tures during an elbow dislocation or in a morę isolated manner. Because the act of throwing places a valgus stress on the elbow, athletes who throw, especially professional pitchers, are subject to injuries of the medial collateral ligament complex. Such injuries most commonly occur insidiously, with repeated overload of the ligament complex leading to pain and ultimately attenuation and abnormal laxity. Occasionally, abnormal laxity occurs acutely with the athlete feeling a sudden pop as the ligament complex tears during one specific act of throwing. The medial collateral ligament complex is assessed using the valgus stress test. This is analogous to the valgus stress test of the knee, but it is a bit morę difficult to properly perform owing to the tendency of the upper limb to rotate when a valgus stress is applied. To minimize this tendency, the test should be performed with the limb fully externally rotated at the shoulder. The elbow is flcxcd about 15° to relax the anterior capsule and unlock the olecranon process from the olecranon fossa, thus minimizing the contributions of the anterior capsule and olecranon process to valgus stability.

For greatcr specificity, the forearm is pronatcd. The examiner may grasp the patienfs forearm with both hands or place one hand below and one hand above the elbow. The examiner then places a gentle valgus stress on the elbow, taking carc to avoid rotating the upper arm at the shoulder (Fig. 3-55). In the normal patient, virtually no valgus laxity should be pcrceptible. In the presence of abnormal valgus laxity, the examiner feels the bones sep-arate slightly when this stress is applied and clunk back together when the stress is relaxed.

The position of forearm rotation can affect the results of the valgus stress test. Valgus laxity with the forearm pronatcd reflects injury to the anterior portion of the medial collateral ligament, whereas valgus laxity in supination may be due to laxity of the anterior portion of the medial collateral ligament or the ulnar part of the lat-eral collateral ligament (see under Posterolateral Rotatory Instability Test, later).

In cases of partial disruption of the medial (ulnar) collateral ligament, the valgus stress test may not be clearly abnormal. In these cases, the examiner should carefully palpatc for tenderness over the medial collateral ligament. In addition, the milking maneuver, described by 0’Brien, will often elicit the patienfs pain. To perform the milking mancuvcr, the examiner grasps the patients thumb and pulls it back, fully flexing the elbow (Fig. 3-56). This places a valgus stress on the elbow, tensing the medial collateral ligament and reproducing the patienfs pain.

Varus Stress Test. Chronić varus laxity of the elbow is assessed using the varus stress test. The details of the

Figurę 3-54. Resisted eccentric forearm pronation test.

Figurę 3-55. Valgus siress test (arrow indicates direction of force applied to forearm).