There are many different injuries that can occur to the knee joint, which is composed of four bones: the femur (thigh bone), the tibia (shin bone), the fibula, which lies parallel to the tibia, and the patella (knee cap). In teens, injuries such as knee fractures and knee dislocations are commonly sustained as sports injuries, from falling or as a result of automobile accidents. The knee is vulnerable to injury because it is a weight-bearing joint.
There are several different types of knee fractures, classified by the severity of the fracture and the location of the fracture. Fractures can be closed or open; closed fractures do not break through the skin and open fractures do. Fractures can also be classified as partial fractures, complete fractures or crush fractures. All knee fractures will cause swelling of the knee joint, so it may be difficult to tell which bone has been fractured until an X-ray image is taken.
Fractures of the patella are commonly caused by falling and landing directly on the kneecap. Patellar fractures can either be a simple crack in the knee cap, or the knee cap can be broken and displaced or shattered. Fractures of the end of the femur are not very common, especially in younger people with strong bones, but this type of fracture can result as the result of a car crash because of the high forces involved in such an accident. Fractures of the top of the tibia are similar in that they are often a result of car accidents in young people. Treatment for knee fractures varies based on the type and severity of the fracture. In general, the knee joint is usually immobilized to allow for healing of the bones. Medications to reduce pain and inflammation may also be given. Certain types of fractures may require surgical reinforcement for proper healing.
The bones of the knee can also be dislocated. A dislocation occurs when a ligament is weak and the bones slide out of place. The knee joint itself may be dislocated when the tibia and femur slide out of alignment. This is rare, however, because this requires severe damage to the ligaments of the knee, like when an accident causes twisting of the knee and tearing of the ligaments that stabilize it. A dislocation of the kneecap is much more common. This injury is painful, but it is less severe than dislocation of the knee joint itself. However, medical attention is still necessary for a dislocated kneecap because an unstable kneecap can result in repeated dislocation injuries. A knee brace may be helpful in treating a dislocated patella.