The ulnar collateral ligament (UCL) is a thick triangular-shaped band of fibrous tissue. It connects between the bottom portion of the humerus (upper arm bone) and the upper portion of the ulna (one of the two bones in the forearm). The UCL is on the medial side of the elbow (side closest to the body).
The elbow ligaments can be torn when there is an injury or dislocation of the elbow. If they do not heal correctly the elbow can be too loose or unstable. The ulnar collateral ligament can also be damaged by overuse and repetitive stress, such as the overhead throwing motion of baseball pitchers, volleyball players, and tennis buffs.
Orthopedic surgeons have been trying for years to find a technique that can stabilize an elbow joint disrupted by a UCL rupture while still allowing for a normal arc of motion. The docking technique is one of the common methods used to reconstruct the ruptured ulnar collateral ligament.
The surgeon drills two holes in the ulna (bone in the forearm connecting to the elbow) and three in the medial epicondyle (the small bump of bone on the inside of the elbow at the end of the humerus).
The two holes in the ulna form a tunnel that a tendon graft to replace the damaged ligament will be looped through. The three holes in the medial epicondyle form a triangle. The bottom hole will be bigger than the top two holes, so that the surgeon can slide the end of the tendon graft into the bottom hole. The two top holes are used to pull the tendon graft into the tunnel using sutures that are attached to the graft and threaded through the two holes.
After the tendon is harvested, sutures are attached to both ends. The tendon is looped through the lower tunnel formed in the ulna, and stretched across the elbow joint. The two sutures attached to the ends of the graft are threaded into the larger bottom tunnel in the medial epicondyle and each is threaded out one of the upper, smaller holes.
Using these two sutures, the surgeon pulls the end of the graft farther into the upper tunnel until the amount of tension is correct to hold the joint in position. The surgeon carefully puts the elbow through its full arc of motion and readjusts the tension on the sutures until he is satisfied that the proper ligamentous tension is restored. The two sutures are tied together to hold the tendon graft in that position.
Another common technique to reconstruct the ulnar collateral ligament is the figure of eight technique. In this technique, the tendon graft is threaded through two pairs of holes – two drilled in the medial epicondye and two in the ulna. The graft is looped through the holes in a figure of eight fashion. The two ends of the tendon are sutured to the tendon itself.
There are several newer techniques being developed that hopefully will make the procedure less invasive while still being as successful as the docking and figure-eight techniques. One new method under investigation combines a ZipLoop, the docking technique, and an interference screw. The ZipLoop device makes it easier to tighten or loosen the graft once it’s in place.