The knee is a joint where the large femur (thigh bone) connects to the tibia (leg bone) It is very vulnerable to injury, especially in the child and adolescent athlete.
Bony Knee Anatomy:
The knee joint is made of three bones. The femur, tibia, and fibula. The fibula is on the outer portion of the leg bone. It serves as a site of attachment of many ligaments and muscles, but does not contribute much to the knee otherwise.
The patella (knee cap) is a large sesamoid that rests on the distal (lower end) of the femur bone. The patella is located within the quadriceps tendon and allows this tendon to be stronger.
There are bony prominences of the tibia that deserve special attention. The first is the tibia spines. The tibia spine serves as the attachment site of the ACL (anterior cruciate ligament). While adolescents and adults tend to get ACL ruptures, younger children are more likely to break the bone than tear the ligament.
The second bony prominence is the tibia tubercle. This is the "bump" that resides on the front of the tibia bone approximately 1-2 inches below the knee cap. The large patella tendon inserts into this prominence. It is very vulnerable to both fractures as well as chronic pain due to overuse, such as with running and jumping.
Acute Injuries Around the Knee
Fractures of the Distal (Bottom Portion) of the Femur Physis (Growth Area):
The distal femur refers to the end of the femur bone near the knee (see picture above). Fractures in this area are quite common in the young adolescent. For more information click here to read about this growth plate injury.
Fractures of the Proximal (Top Portion) of the Tibia Physis (Growth Area):
The proximal tibia refers to the top portion of the tibia bone close to the knee (see picture above). Similar to the distal femur, fractures in this area are quite common in the young adolescent. For more information click here to read about this growth plate injury.
Tibial Tubercle Fractures:
These fractures typically occur if your child lands on a straight knee, such as jumping while playing basketball. The tibia tubercle is the bump under the knee where the large patella tendon inserts. When this bump breaks, it often times needs to be fixed surgically so that the ability to straighten the knee is not compromised. The fracture is typically repaired with a few screws and your child is immobilized in either a cast or a knee brace with the knee held straight for approximately six weeks. Once the cast is removed, physical therapy is often necessary to help strengthen the quadriceps muscle.
Tibial Spine Fractures:
This is a fracture of the bone in the knee where the anterior cruciate ligament (ACL) attaches. These injuries most commonly occur after a child falls off a bicycle. Occasionally, these fractures can be treated without surgery by holding the knee straight in a splint or a cast; however, if the fracture fragment does not line up perfectly, then your physician may recommend a surgery to place the bone in a better position. Most of the times, the surgery can be done arthroscopically with very small incisions. Once the fracture is healed, physical therapy is often necessary to help with recovery.
Please click here to learn more about sports injuries of the knee