Knee injuries—such as fractures, dislocations, sprains and ligament tears—are some of the most common injuries among athletes and non-athletes alike. The knee joint is the largest and most complex joint in the body, and it bears more weight than most other joints—all factors which make it more prone to injury.
Researchers have found that women are more prone to knee injuries than men. In fact, female athletes are two to eight times more likely to suffer an ACL injury than their male counterparts. Why the higher rate of knee injuries in women? Studies suggest that an imbalance in the strength ratio between the quad and hamstring muscles, hormones including estrogen and relaxin, and even anatomical differences such as a wider pelvis may contribute to a higher number of knee injuries in women.
Some of the most common injuries to the knee include tears to the soft tissues in the knee, including ligaments, tendons and cartilage.
The anterior cruciate ligament (ACL), one of the four primary ligaments in the knee, crosses the posterior cruciate ligament (PCL) in the center of the knee. The ACL connects the front of the shinbone to the back of the thighbone and is responsible for preventing the shinbone from sliding forward.
Damage to the ACL, such as a sprain or a tear, is the most common knee injury. Although the ACL can be injured by a direct blow to the knee, most ACL injuries are actually non-contact injuries. Instead, they are often the result of a sudden change in direction or hyper-extension when landing from a jump. ACL tears are common in athletes who play agility sports, such as football, soccer, volleyball, skiing, lacrosse and basketball.
ACL injuries typically require surgical repair through the construction of a new ligament of tissue harvested from one of the tendons around the knee. The rehabilitation period from an ACL injury can vary from six weeks to six months, depending on the severity of the injury.
The medial collateral ligament (MCL) is another of the four primary ligaments in the knee. This ligament runs down the inner part of the knee, from the thighbone to the shinbone. The primary function of the MCL is to prevent an inward over-extension of the knee. The MCL also serves to stabilize the knee and allow it to rotate.
An injury to the MCL most commonly occurs as a result of a direct blow to the outside of the knee that results in a stretch or tear of the MCL and possibly the ACL or other ligaments. Pain or tenderness on the inner side of the knee, stiffness and/or swelling in the knee may be a sign of an MCL tear or strain. The knee may also feel unstable or “lock” or “catch.”
It takes about six weeks for an MCL injury to heal. As the MCL heals, it should be immobilized to keep it stable. Rest, ice, elevation and pain relievers can help reduce pain and swelling due to an MCL injury. A lightweight cast or brace may also be used to restrict movement while the MCL heals. In most cases, the MCL responds well to non-surgical treatment, although in rare cases, surgery may be required.
Recovery from an MCL injury depends on the severity of the injury, but can take anywhere from a few days to a few months.
The meniscus is articular cartilage in the knee joint that acts as a shock absorber for the knee. Injuries to the meniscus can be the result of either traumatic injury, such as a direct blow to the knee, or from degeneration (wear and tear). Degeneration causes a progressive loss of the cartilage tissue, eventually leaving the underlying bone with no protection, which can lead to osteoarthritis in the bone.
Vague pain and swelling in the knee, as well as stiffness and decreased range of motion typically accompany a meniscus injury. In some cases, the individual may experience “locking” or “catching” in the knee.
Injury to the articular cartilage in the knee may be treated through arthroscopic surgery. For more progressive or serious injuries, transplant of cartilage from another area of the knee may be required. In cases where the articular cartilage has completely disintegrated, a total knee replacement may be necessary. Pain and range of motion issues related to a meniscus injury can often be treated with physical therapy, supportive devices or oral/injection drugs, such as an anti-inflammatory.
In addition to torn cartilage, tendons or ligaments in the knee, fractures and dislocations are also common knee injuries. Injuries to the soft tissue in the knee may be prevented through exercises focusing on proper nerve and muscle control of the knee, such as plyometrics, balance and strengthening/stability exercises.