Either an acute traumatic event or a chronic overload syndrome can result in valgus instability of the elbow. Attenuation or rupture of the anterior oblique bundle of the UCL causes this pattern of instability.1,21,22 Medial elbow stability is tested with the patient sitting, the patient's elbow flexed from 20° to 30° to unlock the olecranon from its fossa, and the patient's forearm secured between the examiner's arm and trunk1 (Fig. 3.12). While apply-
ing a valgus stress, the examiner notes the presence of pain and increased medial opening and evaluates the quality of the endpoint. Another method for examining the UCL is to have the patient lie supine with the shoulder abducted to 90° and the elbow flexed from 20° to 300.1 The examiner applies a valgus force against the supinated forearm and uses the opposite thumb to palpate the medial portion of the joint line to determine the amount of opening. O'Driscoll22 tested for stability with the forearm fully pronated so that he would not mistake pos-terolateral instability for valgus instability. Posterolateral instability due to lateral collateral ligament disruption is present when the ulna and radius as a unit rotate away from the humerus in response to a valgus stress. Calloway et al.23 described another variation of the standard technique for evaluating valgus instability. They suggested performing the test at 90° of flexion. In their medial collateral ligament selective cutting study in cadavers, they found valgus opening to be the greatest at this degree of flexion.
Varus instability is caused by disruption of the lateral collateral ligament complex and is present acutely when the elbow dislocates and chronically when the ligament fails to heal.22 This pattern of instability is not as apparent as posterolateral rotatory instability, which is always present when the lateral collateral ligament is disrupted. The examiner conducts a varus stress test with the patient's shoulder internally rotated and the elbow flexed from 20° to 30° to unlock the olecranon. He or she palpates the radiocapitellar joint to detect the degree of opening in the lateral joint line.
Posterolateral rotatory instability is essentially a rotational displacement of the ulna and radius on the humerus that causes the ulna to supinate away from the trochlea.22 In almost all patients, the ulnar part of the lateral collateral ligament is attenuated or disrupted with this pattern of instability.24-26 The examiner can diagnose postero-
lateral rotatory instability using the lateral pivot-shift test.26 With the patient placed in the supine position and the affected extremity placed overhead, the examiner grasps the wrist and elbow. (This grasping is similar to the way that the examiner would hold the knee and ankle when conducting a pivot-shift test on the knee.) The elbow is supinated, and a valgus moment and axial compression are applied as the elbow slowly is moved from full extension to flexion (Fig. 3.13). In a patient who has posterolateral rotatory instability, this movement produces an apprehensive response, because it reproduces the patient's symptoms and a sense that the elbow is about to dislocate. Reproduction of the actual subluxation and reduction is difficult to accomplish in a patient who has not had either local or general anesthesia, because the patient tends to tighten the muscles to guard the joint. The pivot-shift maneuver causes posterolateral subluxation or dislocation of the radius and ulna off the humerus that reaches a maximum at 40° of flexion, creating a pos-terolateral prominence over the dislocated radial head and a dimple between the radius and capitellum. As the elbow is flexed past 40°, reduction of the ulna and radius together on the humerus occurs suddenly and produces a palpable and visible snap (Fig. 3.14).
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Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.