Oregon Family Magazine readers often ask about sports or activity related injuries. We all want our children to be active and involved in physical activity, whether it's organized sports or playing in the yard. With an active, healthy lifestyle, there are also risks to be aware of. One of the most common injuries, particularly for young, growing bodies are those to the knee.  Here we’ll dive deep into the anatomy of the knee… because, as they say, knowledge is power!

Starting with the basics - Ligaments are strong bands of tissue that connect one bone to another. The anterior cruciate ligament (ACL), is one of two ligaments that cross in the middle of the knee.  It connects your thighbone (femur) to your shinbone (tibia) and helps stabilize your knee joint by preventing hyperextension.  Injuries to the ACL occur when the biomechanical limits of the ligament are exceeded.  ACL injuries occur during sports and fitness activities that put undo stress on the knee, and occur most commonly during sporting activities that involve sudden stops, jumping, or changes in direction (i.e. basketball, soccer, football, baseball, tennis, downhill skiing, volleyball and gymnastics). Oddly enough, ACL Injuries are more common in non-contact sports than full contact sports like football and hockey.

Also interesting is, ACL injuries affect women three times more often males.  Studies comparing jumping and landing techniques among men and women athletes have shown women athletes are more likely to land from a jump with their knees together, which increases stress on their knees.  Also, in general, women are more likely to have strength imbalances in their thighs with the muscles at the front of the thigh being stronger than the muscles in the back. The muscles in the back of the thigh prevent the shinbone from moving too far forward; movement that can overextend the ACL.

Many people note a “popping” sensation when the ACL is injured.  The knee may then become painful, become swollen, and feel unstable.  Other structures inside the knee, like the meniscus or other ligaments, may also be injured, but we will cover those another time. If symptoms occur, you should see your doctor as soon as possible.  During the exam, your doctor will check your knee for swelling and tenderness; comparing your injured knee to your uninjured knee is important for comparison. The doctor will also move your knee into a variety of positions to assess range of motion of the ligaments. Often a diagnosis can be made on the basis of the physical exam alone, but other tests may be necessary to assess the severity of the injury. These might include:

• X-rays. To rule out a fracture of bone.
• Magnetic resonance imaging (MRI). To assess the extent of the ACL injury and signs of damage to other tissues in the knee.
• Ultrasound. To assess for injuries in the ligaments, tendons, and muscles of the knee.

Depending on the severity of an ACL injury, treatment may include rest and rehabilitation exercises to help regain strength and stability.  Surgery might also be necessary to replace the torn ligament.  Torn ligaments can be replaced with a tendon transfer from your own hamstring or a ligament transplant from a cadaver.  Rehabilitation, physical therapy, and a proper training program may help reduce the risk of reinjuring the ACL.

Research suggests that training to strengthen muscles of the legs, hips, and lower torso, as well as training to improve jumping and landing techniques may reduce the risk of ACL injury, especially in female athletes.

Long-term consequences of the injury depend on how the stability of the knee has been affected, and the extent to which other structures in the knee were injured.  Severe injuries may lead to progressive, degenerative, arthritis of the knee.

None of us want our children to live with the fear of being injured, or the potential consequences an injury might bring. Being aware of how ACL injuries occur, and being proactive in conditioning and training go a long way in prevention.  It’s the adults (parents) responsibility to encourage a healthy lifestyle, hopefully through positive role modeling, along with an awareness of risks and preventative measures. 

By Greg Phillips