Most commonly, the patient will present with nonspecific pain and clicking about the elbow. While the traumatic dislocation may produce obvious instability, it is much more common for the athlete to present with a more subtle form of instability, due to multiple small injuries. The injured athlete with these more subtle patterns will not give a clear history of a precipitating event, but rather will, more commonly, describe a gradual onset with slow worsening of lateral elbow pain. When O’Driscoll first described this condition, his patients presented with symptoms consistent with recurrent dislocation of the elbow or of the proximal radioulnar joint [1]. Many patients report a history of an elbow dislocation. Almost half of elbow dislocations occurred in sport, including basketball, football, and wrestling in males and gymnastics and skating in females [19].

Patients who partake in racquet sports such as tennis, squash, and racquetball tend to present with signs and symptoms of lateral epicondylitis (tennis elbow); however, a small cohort of patients will injure their LCL complex displaying symptoms of PLRI [19]. Patients with a history of traumatic elbow injury treated with radial head excision will also display symptoms of PLRI [21].

Patients tend to report instability symptoms when the elbow is extended and the forearm is supinated [1]. Other common complaints include pain, giving way, locking, clicking, or snapping of the elbow [1, 2, 4]. These symptoms usually present with the elbow in terminal extension and with the forearm in supination [21]. A common activity patients will describe that exacerbates their symptoms will be carrying a grocery bag and that the elbow feels unstable [5]. Patients will seldom present with recurrent or complete elbow dislocations [22].

Inspection of the injured elbow will often not show any abnormalities, but close visualization may reveal slight swelling along the posterolateral gutter and plica. Palpation is critical in this evaluation to discern the difference between lateral epicondylitis, radial tunnel syndrome, instability, and radiocapitellar arthritis. Sportsmen with instability will not be tender over the radial tunnel and lateral epicondyle but more posteriorly along the back of the radiocapitellar joint. Limited pronation and supination with lateral compression will not be painful, but when valgus force and increased supination in about 100° of flexion is added, the patient will often be tender along the proximal end of the radial ulnohumeral ligament (RUHL) complex and also have increased feelings of instability (Fig. 21.1).

O’Driscoll [1] first described the lateral pivot shift test for PLRI. He describes testing with the extremity above the head of the patient, with the shoulder externally rotated. The test begins with the patient’s forearm fully supinated; the physician then grasps the wrist and flexes the elbow from extension while applying valgus, supinating, and axial forces to the extremity. If PLRI exists, at approximately 40° of flexion, the dislocated radiohumeral joint will be most visible as a posterior prominence and a skin dimple proximal to the radial head. Continued flexion will result in reduction of the joint, and the dimple should disappear. This test is most accurate under anesthesia (Figs. 21.2 and 21.3); however, patients will present with apprehension when awake from the procedure [1].

In most patients, the O’Driscoll test cannot be performed while awake, so our institution uses a modified test where we palpate the posterior radiocapitellar joint while more gently supinating the forearm and providing a slight valgus stress. In extension, there is no shifting or pain, but as the elbow is flexed to 90–110°, the radial head can be felt to shift posteriorly and away from the humerus.

Other tests have been determined from further research into this topic that provides physicians a wide array of exam maneuvers to help provide diagnosis for their patients [4, 15] (Table 21.2).

The initial work-up for LCL injury imaging should begin with anteroposterior and lateral radiographs of the elbow. Radiographs of patients’ elbows consistent with LCL disruption may show some posterior displacement of the radial head relative to the capitellum or a drop sign (slight widening of the ulnohumeral joint, >3 mm) [4, 19]. Other times a small avulsion fragment off of the lateral epicondyle may be present; however, most patients with PLRI present with negative plain radiographs [23] (Fig. 21.4). Stress films may also be obtained, including anteroposterior films with varus loading. A positive finding would show gapping at the lateral joint of the elbow [23]. A stress lateral can be performed with the forearm maximally supinated and a lateral pivot shift being performed. A positive finding would show a widened ulnohumeral joint and an inferiorly subluxated radial head [23].

Magnetic resonance imaging (MRI) may be used to further evaluate the joint in question. Coronal imaging, slices that are <2 mm slices, provides the best visualization of the collateral ligament complexes [11] (Fig. 21.5). In younger patient populations, the LUCL will appear striated on imaging [24]. MRI tends to show LCL tears at the proximal origin of the humeral condyle. If the patient has PLRI, there can be posterior displacement of the ulna and radial head in regard to the humerus, and this has been coined as “perched elbow” [19]. It is recommended to detect ulnar lateral collateral ligament abnormalities that MRI is obtained with three-dimensional gradient-echo and fast-spin-echo sequences [11]. The addition of contrast can aid in the diagnosis [25, 26]. LCL injuries will present as ligament redundancy, attenuation, or discontinuity on imaging [11]. An avulsion fracture may also be seen at the proximal ligamentous attachment or underlying marrow edema in the humerus [27].

In most cases, the magnetic resonance arthrogram represents the most definitive test.