Did you know that there are between 100,000 and 200,000 Anterior Cruciate Ligament (ACL) injuries in the United States each year? It is one of the most common types of knee injuries among active people between 15 to 45 years old. It comprises around 40% of all sports injuries. It's a very serious type of injury, too. When you sprain or tear your ACL, you lose the stability in your knee joint, causing the knee to often give way and buckle. Your knee then swells and becomes too painful for you to even stand. Nearly 30,000 of those patients go on to get reconstruction surgery that costs between $17,000-$25,000 (average cost of an ACL reconstruction surgery in the UK is £6,000) to repair their damaged ligaments.
The ACL is one of the major ligaments in your knee that is responsible for roughly 90% of stability in the knee joint. It helps keep your knee stable when you rotate. You may get ACL injury when get hit very hard on the side of your knee, overextend your knee joint, or suddenly stop and change direction. Don't worry too much if you're a jogger, swimmer, or biker since these activities place little stress on the ACL. However, if you ski, play football, basketball, volleyball, or rugby, then you are at high risk for this type of knee injury. Around 70% of ACL sprains and tears involve little or no contact with other players, while 30 percent result from direct contact. Not surprisingly, males make up most of the cases for anterior cruciate ligament (ACL) injury. However, females have a shockingly higher risk for the injury.
The NCAA statistics says that female athletes are 2 to 8 times more likely to sustain an ACL injury. Studies also reveal that at the age of 14 years, girls have 5 times higher rates of serious non-contact ACL tears than boys. Researchers from Johns Hopkins University set out to find out why. Past studies have come up with a good list of what make women more vulnerable to ACL damage. These include anatomical differences and slower reflex time, but the most intriguing are hormones. Oestrogen, a primarily female hormone, has been known to negatively affect ACL strength and flexibility. However, the Johns Hopkins researchers opted for a newer, unique approach. They decided to study testosterone levels instead.
The researchers wanted to find out what role testosterone has in knee ACL injuries. Is it the key difference between men and women? To find out the answer, they used eight castrated male rats and eight normal male rats. The castrated rats have an average testosterone level of 0.14 ng/mL, while the group of normal rats have 3.54 ng/mL. After measuring the ligament strengths of both groups of rodents, they found that the normal rats with higher testosterone levels have stronger ACLs. This clearly indicates that testosterone may influence ACL strength and the injury rate of the ligament.
Specifically, the study found that it takes 15 percent more force to cause ACL injuries on the rats that have higher testosterone levels. In order to tear the rats' ligaments, the researchers had to exert 34.6 Newtons on the group with higher testosterone, while only 29.2 Newtons on the castrated group. Researchers believe the finding could eventually pave way for the development of a method to use hormones in preventing knee injuries. In the future, you may only need to have your testosterone levels tested to see if you need training strategies to strengthen your ligament and reduce the chance of getting an ACL injury.
In the meantime, preventative rehabilitation programs are the key to keeping your ACL injury free. These exercises include training drills that require balance, power and agility. They have been found to reduce the risk of ACL damage. Many sports physicians highly recommend these exercises to their female players. Knee conditioning exercises allow women to have more active lifestyles and participate in more sports without having to fear disabilities from ACL injuries.