Ulnar Collateral Ligament Injuries of the Elbow

Sprain or tearing of the ulnar collateral ligament (UCL) of the elbow secondary to acute or chronic valgus stress leading to pain, instability, and dysfunction

2 main mechanisms: chronic deterioration of the UCL owing to repetitive valgus overload or, less commonly, an acute traumatic rupture

Most UCL injuries are seen in baseball players, but they also can be seen in wrestlers, javelin throwers, tennis players, football players, volleyball players, and in acute trauma victims.

UCL injuries typically are seen in skeletally mature athletes; skeletally immature athletes with open physes sustain medial apophyseal avulsion injuries but typically maintain an intact UCL.

Predominant gender: Male > Female.

Although the exact prevalence of UCL injury is unknown, there has been a definite increase in the number of surgical reconstructions performed in professional, collegiate, and high school athletes in recent years. This rapid increase has been attributed to overuse as well as improved diagnostics.

Participation in sport that demands repetitive excessive valgus stress to the elbow, such as high-velocity throwing or overhead activity, is a risk factor for chronic injury.

Throwers who become front-on too early in the throwing motion are at increased risk.

Contact sports or sports with significant fall risk are a factor in acute injury.

Athletes who participate in throwing or overhead sports should be on a conditioning program that includes core stabilization, rotator cuff and forearm muscle strengthening, and posterior capsule stretching.

Athletic technique should be reviewed to minimize valgus stress to the elbow.

Single-sport athletes should have a 3-mo rest within a year.

The UCL is the primary restraint to valgus stress of the elbow in flexion.

The UCL is composed of 3 ligaments: The anterior bundle, posterior bundle, and transverse ligament.

The anterior bundle, which is composed of an anterior and posterior band with reciprocal functions, is the most important medial stabilizer of the elbow (1)[A]. Rupture of the anterior bundle is considered a complete tear of the UCL.

The posterior bundle provides secondary restraint beyond 90 degrees of flexion.

The transverse ligament is an extension of the joint capsule and does not contribute to valgus stability (2)[A].

Repetitive valgus load to the elbow is absorbed primarily by the UCL.

Over time, the UCL becomes overloaded, and microtraumatic tears occur, leading to altered elbow kinematics.

Cumulative microtrauma can lead to rupture of the UCL; altered mechanics lead to decreased throwing or hitting accuracy and velocity.

Acute rupture can occur in a previously attenuated ligament or in a normal ligament subjected to extreme valgus stress, such as an elbow dislocation.

Valgus-extension overload syndrome: Radiocapitellar and posteromedial olecranon impingement

Ulnar neuritis or subluxation

Loose osteochondral bodies

In acute rupture, the athlete may experience sudden pain, sometimes with an audible pop, and cannot resume play.

Chronic injuries present as persistent, insidious medial elbow pain, often accompanied by decreased command and velocity of throwing or hitting.

Tenderness along the UCL

Joint effusion and ulnar nerve tenderness may be present.

Flexion contracture with pain at terminal extension is common.

Valgus stress test: The examiner stabilizes the arm and flexes the elbow to 30 degrees; valgus stress is applied. The test is positive if the athlete has pain, apprehension, or instability.

Milking maneuver: The forearm is supinated and the elbow flexed to 90 degrees; the examiner applies a valgus stress by pulling on the thumb while palpating along the UCL. Pain, apprehension, or instability indicate MCL injury, but this test can give a high number of false-positive results (3)[B].

Moving valgus stress test: This test is highly sensitive and specific for UCL injury (3)[A]. A constant valgus stress is placed on the elbow as the joint is moved through the arc of flexion and extension. The test is positive if the athlete's pain is reproduced between 70 and 120 degrees of flexion.

Flexor/pronator tendonitis or rupture

Ulnar neuritis or subluxation

Medial triceps subluxation

Loose bodies

Olecranon osteophytosis

Medial epicondyle avulsion

Pronator syndrome