“I blew out my knee.”
What exactly does this mean?
Most often this means a torn ACL, and it seems like everyone either has their own or knows someone with an injury story. What makes this injury especially infamous is the fact that the mechanism of injury can often seem completely random. ACL tears are in a minority of injuries caused by non-contact forces. Translation: the injury can be caused by cutting or landing awkwardly from a jump. What can predispose someone to an ACL injury? In the following paragraphs I will briefly describe what an ACL injury is, discuss predisposing factors, and review prevention programs.
The Anterior Cruciate Ligament (ACL) is one of the ligaments that cross the middle of the knee joint and connect the femur (thigh bone) to the tibia (shin bone) and help stabilize the knee. Ligaments are strong bands of tissue and are primarily resilient against forces; however, when stretched too far will tear. There is not enough blood supply to the area for the Anterior Cruciate Ligament to heal without surgical intervention. The ligament is repaired by creating a new ACL from grafted tissue, either from the person themself or a cadaver. Rehabilitation is started quickly after surgery and will continue for six to twelve months.
ACL injuries can happen in any sport but are most common in sports where cutting and jumping is involved, such as basketball or soccer. ACL injuries present more frequently in women, reasons for which are being consistently researched. It is believed that hormones affect ACL strength, making women more at risk at different times throughout their menstrual cycle. Women also commonly have a greater difference in ratio of quadriceps to hamstring strength than men. Lastly, much of an ACL injury has to do with mechanics and women typically land more straight legged from jumping, thus increasing the force placed on the knees. Though hormones cannot be changed, strength and mechanics can be improved through an ACL prevention program.
Different literature will suggest different ACL prevention programs, but most have commonalities. As mentioned above, proper mechanics when jumping should be practiced. When landing, you want to soften your lower body to absorb force. This is accomplished by landing with the knees and hips bent, never straight. In sports that emphasize quadriceps strength in women the hamstrings should not be neglected in a training program. Most programs promote a combination of stretching, proprioception (awareness/balance), strengthening, plyometric (fast, powerful movements like jumping) and agility drills. It is generally accepted that the most important concept is plyometric drills, making sure to emphasize proper technique. Examples include; box jumps, squat jumps, or power skipping. While nothing can guarantee you won’t be injured, one positive of ACL prevention training is that it is not specific to the injury. An increase in stretching, plyometric and agility drills, as well as strength training will make you overall a better athlete.