Surprisingly, Frobell et al found that it’s not clear if a torn anterior cruciate ligament should be surgically repaired. In a randomized, controlled study of 121 young adults with acute ACL injury, there was little difference between getting reconstructive surgery right away and just doing normal rehabilitation. Given the structural importance of the ACL ligament, it’s amazing that it can recover from major trauma without surgery approximately as well as it can without. This study did not show that ACL repair is never or rarely necessary, but it certainly strongly suggests that it’s less crucial than most people would expect.
“A randomized trial of treatment for acute anterior cruciate ligament tears”