what is an ucl
Request a Consultation. The ulnar collateral ligament (UCL) of the elbow is a structure that is critical for elbow stability. The UCL is a triangular, thick section of tissue that maintains a healthy and normal valgus relationship between the arm bone (humerus) and the ulna (one of the bones found in the forearm). An ulnar collateral ligament injury can range from a mild stretch, to a full tear.