The most commonly torn elbow ligament in baseball players is the medial collateral ligament (MCL). Sometimes they call this the ulnar collateral ligament (UCL). It's on the side of the elbow closest to the body. Medial means inside and ulnar refers to the bone along that side of the forearm. That's how it gets two different names for the same thing.
Injuries of this ligament can sometimes be treated without surgery. But most of the time surgery is needed. This is especially true for athletes. In the few cases that the ligament retears, a second operation is needed.
Results of the surgery are classified as excellent, good, fair, and poor. Excellent means that after surgery the player returns to the game at the same level as before the injury. The athlete participates for at least one full year.
A good outcome is described as returning to a lower level of play but for more than one year. The player is able to throw or pitch daily during practice. Players with a fair result are able to play recreationally. And a poor result means the athlete can't throw or compete at any level.
Studies show that 85 per cent of players have an excellent result after the first repair. About two percent retear the ligament requiring a revision (second) surgery. Forty per cent (40%) of the players who have a revision procedure have complications. Problems such as stiffness, retear, and scar tissue have been reported.
There doesn't seem to be any way to predict who might have problems after this type of surgery. It's impossible to tell who will be able to return to full participation in sports.