Over the last 2 decades, the number of teen females involved in competitive sports has skyrocketed. Research studies continue to show that girls involved in sports have better self-esteem and reduce the risk of obesity.But this involvement in competitive sports has not come without a cost. Recent studies have shown that females are four to six times more likely to tear their anterior cruciate ligament (ACL) than are their male counterparts playing the same sport.1,2 But why is this? And can it be prevented?
Researchers have spent countless hours studying videos to better determine why females are at greater risk. Their findings showed that there were many contributing factors for the difference between the sexes. The general mechanics that put the ACL at risk are landing on an extended knee, the center of mass being off the base, and internal rotation and adduction of the knee. These combined movements put the ACL at its most vulnerable position.
Dr. Francine Pearce
Hormones are another contributing factor. Estrogen and relaxin give strength and flexibility to the ligaments. But during surges of these hormones – such as during menses or a growth spurt – there is laxity within the ligament, putting it at further risk of injury.1 Testosterone increases muscle mass and strength. For males, this is protective because they rely less on their ligaments during jumping and deceleration. Puberty also contributes to the increased risk by accelerating the body mass index quickly over a short period, and therefore, greater strength is needed.1,3
Core strength, which helps with balance, is another contributing factor. Females tend to have lower core strength, which puts them at greater risk for rotational forces, especially when landing on one foot.1,4 As core strength improves, athletes can change direction more efficiently and hold their bodies upright on a single limb, which prevents the torsion that contributes to injury.
Prevention for ACL injuries occurs through very specific training in repetitive jumping and balance exercises are known as plyometric exercises. Neuromuscular training (NMT) includes plyometric training along with strengthening exercises such as lunges, squats, and plank exercises.4 One can reduce the risk of injury by 72% with 6-8 weeks of training by a professional experienced in NMT.5
Educating parents on the increased risk of injury to the ACL in females and importance of proper training can reduce injury and the risk of degenerative joint disease in later years.6 The Institute for Sports Medicine has a website that offers a knee injury prevention program you can refer families to for more information to prevent knee injuries. Sportsmetrics can help locate an NMT professional near them. Knowledge is power!
Reference
1. Pediatrics. 2014 May;133(5):e1437-50
2. Bull Hosp Jt Dis. 2000;59(4):217-26
3. Clin Biomech (Bristol, Avon). 2006 Dec;21(10):1060-6
4. Am J Phys Med Rehabil. 2005 Feb;84(2):122-30
5. Am J Sports Med. 2008 Aug;36(8):1476-83
6. Curr Womens Health Rep. 2001 Dec;1(3):218-24
Dr. Pearce is a pediatrician in Frankfort, Ill. Email her at pdnews@frontlinemedcom.com.