Originally Posted by AtomicDumpling
From what I understand, ligaments do not repair themselves if the damage is more than microscopic. Ligaments do not fuse back together like broken bones do. Ligaments do not heal like a cut does. Once a ligament is torn the only way to get back to 100% is to replace the ligament with a new one.
That is correct. As Red Raindog mentioned, it is because there is not an adequate supply of blood flow to ligaments, which would promote the healing process. I've read about ultrasound being used to increase blood flow and promote healing during the course of physical therapy for non-athletes, but to my knowledge, I'm not aware of it being used in athletes because of the amount of stress placed on the ligament during athletic activities. Even if it were to heal, the ligament would be significantly weaker and susceptible to further injury, which is why Tommy John Surgery is almost universally recommended in pitchers.
Regardless, this sucks for Harvey. I wish him the best.