Ulnar Collateral Ligament Injury

Updated: Dec 22, 2021
Author: Robert F Kacprowicz, MD, FAAEM; Chief Editor: Sherwin SW Ho, MD 


Practice Essentials

The ulnar collateral ligament (UCL) of the elbow is critical for valgus stability of the elbow and is the primary elbow stabilizer.[1, 2]  As such, the UCL plays an important role in most throwing sports, including baseball and javelin, as well as racquet sports and ice hockey.

Elbow injuries in young athletes are generally chronic, with persistent pain and instability from repetitive overhead activities. In the athlete, ligamentous injury can also be heralded by an acute traumatic event such as an elbow dislocation. This can then lead to chronic pain and valgus instability. An understanding of the anatomy and biomechanics of the elbow in throwing sports is essential to the correct diagnosis and treatment of this potentially disabling injury.[3]

Functional Anatomy

The UCL originates at the posterior distal aspect of the medial epicondyle and inserts into the base of the coronoid process. At 90 º of flexion, it provides 55% of the resistance to valgus stress at the elbow. In full extension, the UCL, bony architecture, and anterior capsule equally maintain valgus stability.

The UCL is composed of 3 bands: anterior, posterior, and transverse. The anterior band, which arises from the anteroinferior surface of the medial epicondyle and inserts on the sublime tubercle of the ulna, provides the major contribution to valgus stability.

Sport-Specific Biomechanics

The acceleration phase of the overhead throw causes the greatest amount of valgus stress to the elbow.[4] Extension occurs at a rate of up to 2500 º per second and continues to 20 º of flexion. During this phase, the forearm lags behind the upper arm and generates valgus stress while the elbow is primarily dependent on the anterior band of the UCL for stability. During the acceleration phase, valgus stress can exceed 60 Newton meters (Nm), which is significantly higher than the measured strength of the UCL in cadavers. The valgus force can, therefore, overcome the tensile strength of the UCL and cause either chronic microscopic tears or acute rupture.

Bushnell et al examined maximum pitch velocity and elbow injury in 23 professional baseball pitchers over a period of 4 seasons and found a statistically significant association (P = .0354).[5] Of 9 pitchers who had elbow injuries, 4 had an elbow muscle strain and/or joint inflammation, and 5 had an ulnar collateral ligament sprain or tear. Surgery was required for 3 of the 5 players with ulnar collateral ligament injuries; these pitchers also had the highest maximum ball velocity.[5]

A study by DeFroda et al found that there is a statistically significant difference in the mean fastball velocity of pitchers who injure their UCL. Players who injured the UCL tended to have higher fastball velocities.  The study also added that there has been an increased incidence of injury in the first 3 months of the season and that early tears are more likely to occur in relief pitchers than starters.[6]


Repetitive throwing motions are the most common cause of UCL injury in the athlete.

Traumatic valgus stress to the elbow during a fall or with the arm outstretched may lead to UCL rupture in association with elbow dislocation.


Return to competitive throwing by the patient is possible after successful rehabilitation and reconstruction, when indicated.

A literature review by Hadley et al showed that return-to-play rates among high school athletes after UCL reconstruction ranged from 66.67% to 91.49%. Baseball players had a mean rate of return to play of 84.4%.[7]


Ulnar nerve injury or entrapment may occur. Chronic instability is possible.

Patient Education

Proper throwing technique is essential to preventing UCL injuries; therefore, athlete education is critical. Analysis of the athlete's throwing technique and constructive criticism by coaches may be helpful.




Medial elbow pain is the most common symptom in athletes who throw. Pain may be especially prominent during the acceleration phase of the overhead throw.

Pain is often chronic or recurrent, and it may lead to a slow erosion of the patient's throwing ability. Athletes may report having had similar pain in previous seasons of throwing.

Rest generally helps to relieve the pain.

Occasionally, during a single throw, athletes may experience acute pain over the medial elbow, sometimes associated with a popping sensation, that causes them to immediately stop throwing.

Physical Examination

Medial elbow tenderness and swelling are the most notable findings. Tenderness is commonly found approximately 2 cm distal to the medial epicondyle. UCL tenderness may occasionally be difficult to differentiate from flexor pronator tendinitis, but the pain of flexor pronator tendinitis is aggravated by resisting forearm pronation.

Loss of elbow range of motion (ROM) is occasionally observed.

With acute rupture, ecchymosis may be observed over the medial elbow.

Pain may be reproduced when the patient makes a clenched fist.

Valgus stress with the elbow in 25° of flexion (elbow abduction stress test) reproduces pain and may cause joint opening. The affected side should be compared with the contralateral elbow as a reference for baseline laxity.

Some throwing athletes have a baseline asymmetry; therefore, preseason documentation of baseline elbow laxity in elite athletes, especially pitchers, may be helpful for comparison if an injury occurs during the season.





Laboratory Studies

Laboratory studies are not indicated during the workup of UCL injuries.

Imaging Studies


Findings from routine radiography can occasionally be diagnostic if an avulsion fragment is seen, and in a minority of patients, this study can also reveal secondary findings that are suggestive of UCL injury, such as ossification of the ligament. Plain radiographs are also helpful to rule out other causes of elbow pain, such as epitrochlear osteophytes, epicondylar fractures, posterior olecranon fossa loose bodies, ligamentous calcification, or capitellar lesions.[8]

Manual or instrumented valgus stress radiography can be used to document increased joint opening and ligamentous laxity. Significant asymmetry may be observed in traumatic elbow injuries such as dislocations, whereas laxity in a throwing athlete may not be so obvious, with only a very subtle asymmetry.

Gravity stress radiography—with the patient supine, the shoulder in maximal external rotation, and the weight of the forearm resisted by the UCL—may also be helpful.[9]

Plain arthrography

This imaging modality is not indicated because dye leak has been shown to be inconsistent in cases of chronic laxity, and only an acute event may be anticipated to exhibit a positive finding.

Magnetic resonance imaging (MRI)

Plain MRI is a useful study; however, because of the relatively small size of the UCL, the overall sensitivity of MRI is 57-79%[10]

MR arthrography

This is the most useful imaging modality, with a sensitivity of 97% for UCL injury, and can provide detailed definition of the UCL and associated injuries.[11] Partial-thickness tears can be differentiated from complete tears with MR arthrography. Partial tears demonstrate high signal intensity in the ligament and may show disruption of some fibers, and full-thickness tears are often seen either in the middle of the UCL or at either the distal attachment on the coronoid or at the origin at the medial epicondyle.[12]


This modality allows for rapid evaluation of the UCL. A ruptured UCL on an ultrasound appears as a discontinuity of the ligament with fluid in the gap between ends or as nonvisualization of the ligament. Sprains appear as thickening, decreased echogenicity of the ligament, and/or edema when compared with the normal ligament.[13]

Computed tomography scanning (CT) with intra-articular contrast

This technique has been studied in small numbers of patients. CT scanning with intra-articular contrast appears to be highly sensitive and specific for both acute and chronic injuries,[10] but more data are needed before widespread use can be recommended.


Arthroscopy is believed by some authors to be the most specific diagnostic procedure because it allows visualization of the medial compartment while valgus stress is applied; however, clinical suspicion of a UCL injury via a good history and physical examination is probably the most reliable in making the diagnosis.



Acute Phase

Rehabilitation Program

Physical Therapy

Generally, 3-6 months of conservative therapy with rest, nonsteroidal anti-inflammatory drugs (NSAIDs), and local physical therapy for ROM are necessary for recovery.

Recreational Therapy

When pain and swelling completely resolve and the athlete has returned to a premorbid ROM (usually not before 3 months of treatment), progressive return to activity with increasing velocity and duration of training may be attempted.

Medical Issues/Complications

Surgery may be considered in several situations. Surgical repair is generally indicated for acute tears in competitive athletes, when chronic instability exists, and when the patient has recurring pain and laxity after 2 or more attempts at conservative therapy.

Surgical Intervention

Direct repair of the ligament is generally not indicated. Reconstruction of the UCL (eg, repair of the anterior bundle) is the more common approach to surgical treatment, with use of a palmaris longus tendon autograft. The graft is pulled through bone tunnels in the medial epicondyle of the humerus and the sublime tubercle of the ulna in a figure-8 pattern. Ulnar nerve transposition may be undertaken at the time of surgery, if indicated.


Consultation with an orthopedic surgeon, preferably a sports or upper-extremity specialist, is indicated when surgical intervention is contemplated.

Other Treatment

Steroid injection is not recommended for UCL injuries.

Platelet-rich plasma has shown promise in a case series of throwing athletes with partial UCL tears who had failed conservative treatment. Of these athletes, 88% were able to return to throwing activities an average of 12 weeks after a single injection of platelet-rich plasma.[14]

Recovery Phase

Rehabilitation Program

Physical Therapy

After surgery, the elbow is immobilized in a posterior splint for 10 days in 90° of flexion. The wrist is maintained free, and a soft rubber ball is given to the patient for squeezing to maintain grip strength. Active ROM is initiated after removal of the posterior splint. A hinged brace that prevents valgus stress should be used.

At approximately 1 month after surgery, isometric strengthening exercises should be initiated. Limited progressive strengthening can be initiated at 8 weeks and plyometrics at 12 weeks. Shoulder and elbow exercises should be instituted as soon as feasible, but valgus stress of the elbow should be avoided for at least 4-6 months until the graft has had sufficient time to incorporate.

Recreational Therapy

After 4-6 months, throwing may be resumed with a training program that is designed to return the patient to competitive throwing by 9-12 months after surgery.

Medical Issues/Complications

Both transient and permanent ulnar neuropathy may occur after reconstruction, occasionally requiring ulnar nerve transposition or revision of transposition. Flexion contracture (generally < 5°) may also occur in 25-30% of patients.

Surgical Intervention

Ulnar nerve transposition (or revision of transposition) may be required for persistent postoperative ulnar neuropathy.

Maintenance Phase

Rehabilitation Program

Physical Therapy

Flexibility and strength training of the elbow are useful in the maintenance phase to prevent recurrent injury.

Recreational Therapy

During the maintenance phase, particular attention to the patient's throwing technique is essential to prevent recurrence of injury.

Medical Issues/Complications

Long-term complications may include chronic pain with throwing and chronic instability of the elbow.



Medication Summary

NSAIDs are the cornerstone of therapy for the control of pain that is associated with UCL injuries.


Class Summary

Pain control is essential to patient care.

Ibuprofen (Ibuprin, Motrin, Advil)

DOC for treating mild to moderate pain if no contraindications exist. Inhibits inflammatory reactions and pain by decreasing the activity of the enzyme COX and thereby inhibiting production of prostaglandins.

Acetaminophen (Tylenol, Feverall, Aspirin Free Anacin, Tempra)

DOC for treating mild pain in patients with documented hypersensitivity to aspirin or NSAIDs, those diagnosed with upper GI disease, or those who take PO anticoagulants.

Naproxen (Naprosyn, Anaprox, Naprelan)

Used for relief of mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing the activity of the enzyme COX and thereby inhibiting production of prostaglandins.

Ketoprofen (Oruvail, Orudis, Actron)

Used to relieve mild to moderate pain and inflammation. Initially administer small dosages to patients with a small body size, elderly patients, and those with renal or liver disease. Doses >75 mg do not increase therapeutic effects. Administer high doses with caution, and closely observe patients for response.

Codeine/acetaminophen (Tylenol with codeine #3)

Drug combination indicated for treatment of mild to moderate pain.

Oxycodone and acetaminophen (Percocet)

Drug combination indicated to relieve moderate to severe pain. DOC for aspirin-hypersensitive patients.

Hydrocodone bitartrate and acetaminophen (Vicodin, Lortab, Norcet)

Drug combination indicated to relieve moderate to severe pain.



Return to Play

Competition may be resumed when the following criteria are met:

  • The athlete is pain free with throwing.

  • Elbow and shoulder ROM has returned to within normal limits.

  • Forearm strength has returned to baseline.

  • Good throwing biomechanics have been established.


Injuries to the UCL are best prevented by ensuring proper throwing biomechanics. Coaches are essential to assessing the proper throwing techniques in the athlete. Thorough warm-up and flexibility exercises also play an essential role in preventing UCL injuries.