Elbow Instability (Ulnar Collateral Ligament Injury – UCL)
Elbow instability, or looseness of the elbow joint, occurs when the ulnar collateral ligament (UCL) is injured. The UCL is located on the inner side of the elbow and connects the bony bump of the upper arm (medial epicondyle) to the larger forearm bone (ulna). This ligament provides critical stability during throwing and weight-bearing activities.
The UCL ligament is most commonly affected by overuse injuries in throwing athletes such as baseball or softball players. However, it can also be injured in sports that place weight on the arms—such as wrestling and gymnastics—or after an elbow dislocation. Although uncommon in children who are still growing (because growth plate injuries are more frequent), UCL injuries can occur in older youth and adolescents. Another elbow condition that can affect athletes is tennis elbow, which involves different structures of the joint.
UCL Injury Symptoms
Common signs and symptoms of a UCL injury or elbow instability include:
- Pain on the inner side of the elbow joint when throwing or pushing up from a seated position
- Swelling around the elbow joint
- A sense of looseness or instability when bearing weight on the elbow
- Decreased throwing speed or accuracy
UCL Injury Diagnosis
Diagnosis typically involves a review of symptoms, the athlete’s throwing history, and a physical exam of the elbow. X-rays can rule out fractures, while an MRI with dye provides a detailed look at the ulnar collateral ligament and other soft-tissue structures. This imaging helps determine whether the ligament is partially or completely torn and if any loose bodies are present in the joint.
UCL Injury Treatment
Treatment depends on the severity of the tear and the athlete’s activity level:
- Non-surgical treatment: Incomplete or partial tears can often be treated conservatively with rest, physical therapy, and activity modification. This includes stopping all throwing—both in organized sports and casual settings—until cleared by a physician. Strengthening exercises around the elbow can help improve stability and support healing.
- Surgical treatment (UCL reconstruction): A complete tear, or a partial tear that does not respond to rest, may require UCL surgery. This procedure is known as ulnar collateral ligament reconstruction or Tommy John surgery. During surgery, a tendon graft is used to reconstruct the damaged ligament and restore stability. Patients who undergo this surgery typically refrain from pitching for about one year while completing a structured rehabilitation program.
Some athletes may choose to stop high-stress throwing activities altogether, as UCL injuries generally do not affect daily movement or routine tasks. However, many individuals who undergo Tommy John surgery are able to make a successful return to pitching and competitive sports with proper recovery and rehabilitation.
Expert Pediatric Care at Rady Children’s
The Sports Medicine and Orthopedics team at Rady Children’s Hospital–San Diego specializes in diagnosing and treating UCL injuries and other elbow conditions in young athletes. Our pediatric orthopedic surgeons and physical therapists provide personalized care—from initial diagnosis to recovery and return-to-play guidance—helping each child heal safely and regain confidence in their sport.