If you play high school or college sports or are just a fan of various sporting events, then you know about Anterior Cruciate Ligament (ACL) injuries. It is estimated that 200,000 ACL ruptures occur in the U.S. per year. The ACL is one of four major ligaments around the knee that stabilizes the knee when performing cutting, pivoting and jumping activities.
The ACL is commonly torn while participating in a sport that involves a quick change of direction. Over 90% of ACL ruptures occur from a non-contact injury where the foot is planted and torque is placed on the knee. It is a move that the athlete has performed thousands of times without injury and appears to the viewer as a "nothing injury". Less commonly the ACL tears as a result from a contact injury when the knee is struck from the lateral (outside) and anterior (front) aspect. Contact injuries usually cause concomitant damage to other ligaments such as the MCL and the meniscus.
As youth participation in sports has increased in the last decade, serious sports-related injuries have become a more common problem. ACL reconstructions have a major financial impact on the health care system. One study showed that the cost for ACL reconstructions is estimated at between $5,000 and $17,000. ACL tears also can influence scholarship offers. Because of these factors, ACL prevention programs have become popular. But the question has come up whether or not these programs are cost-effective, and do they reduce the risk of tearing the ACL.
ACL prevention programs must first recognize risk factors for tearing the ACL. Females tear their ACL 6-8 times more frequently than males. Females have a smaller ACL, a valgus (knock-kneed) alignment, weaker hamstrings compared to their quadriceps and lack of neuromuscular control. There are many ACL prevention programs with the most popular being the Sportsmetric Program from Cincinnati and the PEP program. A recent study showed that these programs reduced the incidence of ACL tears by 63%, savings of $275 per player per season and that neuromuscular training is more cost effective than screening for risk factors.
With the increase in the incidence of ACL tears, we have also seen an increase in re-tears of the ACL. Studies have shown that patients, who tear their ACL at a young age, those who participate in cutting and pivoting sports and males have a higher risk of tearing their ACL graft. Graft choice also influences the re-tear rate with allografts (cadaver/donor tissue) having a higher failure rate than autografts (own tissue).
Tearing the ACL and re-tearing the ACL graft increases the risk for damage to other structures in the knee such as the meniscus and articular cartilage. Even though the meniscus can be repaired, a majority of the time the meniscus tear is resected. Removing a part of the meniscus and damage to the articular cartilage increases the risk of developing osteoarthritis. Studies have shown that over 50% of patients that tear their ACL will develop osteoarthritis of the knee within 10-15 years from the injury. Surprisingly, the re-tear rate of the ACL between males and females are not significantly different.
Tearing the ACL graft is devastating to an athlete but tearing the contralateral ACL is equally disappointing. The recovery time from an ACL reconstruction is approximately one year. Re-tears and tears of the opposite ACL commonly occur in the first 2 years after the initial ACL reconstruction. Females have about a 20% increased risk of tearing the contralateral ACL. Studies have also shown that patients who have an ACL reconstruction using hamstring autograft compared to patellar tendon autograft have a lower risk of tearing the opposite ACL but the reason for this finding is not clear.
If an athlete tears their ACL and wants to continue to play sports, then they need to have an ACL reconstruction. However, returning to sports after an ACL reconstruction can increase the risk for re-tear and for developing early arthritic changes in that knee. In addition, if the risks for tearing the ACL are not corrected at the time of returning to athletic activities, then there is a higher re-tear rate. ACL prevention programs have been shown through scientific research to be effective in decreasing the risk of tearing, re-tearing the ACL and tearing the contralateral ACL. Therefore, it is suggested that all athletes should take an active role in participating in ACL prevention programs and make it part of their regular workout routine.