Growth Plate Fractures
As shown in the x-ray, each long bone has three separate portions to it:
- Epiphysis – represents each end of the bone
- Diaphysis– represents the middle of the bone
- Metaphysis – portion of the bone between the epiphysis and diaphysis
Bone is inherently stronger than cartilage and therefore, if given the correct mechanism of injury, the cartilage is more likely to be injured than the surrounding bone. Since the growth plate is made of cartilage, it becomes more susceptible to injury given the right circumstances.The "growth plate" of the bone, sits between the metaphysis and the epiphysis, and is actually called the physis. As the name suggests, this growth plate is the area from which the bone grows. As you can see on the x-ray, the physis is dark while the remainder of the bone is white. This is because the growth plate is made of cartilage and cartilage does not have calcium. Bone, of course, does have calcium and it is the calcification within bone that gives it a white appearance on x-rays.
The problem with growth plate fractures is that there is a chance that the injury can lead to either complete destruction of the growth area or a partial destruction. If the entire growth area is disturbed, that may lead to one limb being longer than another. If only a portion of the growth area is disturbed, not only may the limb be shorter, but it may be crooked as well.
The most common growth plate fractures treated at COA are as follows:
Proximal refers to the top, and therefore, a proximal humerus growth plate fracture means that the fracture occurs through the physis of the humerus (arm) bone near the shoulder joint up at the top. This growth plate accounts for 80% of the growth of the arm. Luckily, when this growth plate is injured, it very rarely results in permanent damage. Furthermore, since so much growth occurs through this area, it is also the reason why fractures at or near the growth area can heal very crooked, because as long as your child has at least a few years of growth left remaining, the arm will straighten itself out with time.
While proximal refers to the top end, distal refers to the bottom end, and so the distal radius represents the end of the radius (forearm bone) near the wrist. Injury to this growth plate is extremely common. It occurs after someone falls and he puts his hand out to break his fall. Often times, this type of injury separates the epiphysis of the bone far away from the metaphysis. If your child is in the emergency room with this type of injury, it will often be recommended that one of the younger orthopaedic physicians “sets” the bone in a better place to allow the bone to heal without deformity. However, similar to the proximal humerus, the bone does not have to look perfect on an x-ray to heal perfectly. Again, this is due to the amount of growth potential that the distal radius has compared to its proximal growth area. Occasionally, injuries to the distal radius, or more commonly, the distal ulna (the other forearm bone) growth plate may lead to a growth arrest. If growth arrest occurs in only one bone but not the other, than this may lead to one bone growing longer than the other in the forearm. This may make the wrist appear crooked. Your provider will often ask you and your child to return for an x-ray approximately 6 months after the fracture to look for this type of growth problem. If it is caught early, there are measures that can be done prior to the wrist growing crooked.
The distal femur refers to the end of the femur bone near the knee. This growth plate contributes a significant amount to the growth of not only the femur bone, but of the entire lower extremity. This growth area is tethered closely to the bone, and so it takes a significant force in order to break it. Unfortunately, when this area breaks, it almost always requires surgery to realign the bone ends back together. Even if the bones are lined up perfectly, there is still almost a 50% chance that the growth plate will suffer some type of permanent injury. Since it contributes to a large portion of growth, it is very important to follow up with your surgeon regularly.
Depending on where the bone breaks, your surgeon will either repair the fracture with pins or screws. If pins are placed across the bone, they will remain outside the skin for approximately 4-6 weeks. During that time, the pins will remain protected by a cast and are then removed in the office. Once the pins have been removed, then your child will be allowed to start moving his/her knee. If the fracture is repaired with screws, then often times, your surgeon will not allow your child to put weight on the leg for the first 6 weeks to allow the fracture to heal. Most of the time, the screws are not bothersome and can be left in place forever.
The proximal tibia refers to the top portion of the tibia bone close to the knee. Similar to the distal femur, it contributes a large portion to growth of the limb, and has a high risk of growth arrest if the fracture occurs through the growth plate. Also similar to the distal femur, when breaks occur through the physis, often times, the pieces are separated far enough away from each other that it requires surgery to piece them back together. Most of the time, your physician will use sterile metal pins that are placed outside the skin and across the bone to hold the fracture in place. The pins typically stay in place for a total of 4-6 weeks. Once the fracture heals, then the pins will be removed, and your provider will allow your child to begin walking on the leg again. Approximately six months after the fracture is when your child will have x-rays taken to determine whether or not the growth plate is permanently injured.
These growth plate fractures occur near the ankle joint. In younger children, the fracture fragments typically are not separated from each other and these go on to heal uneventfully most of the time. There are different types of growth plate fractures that occur in adolescence, and the type of fracture that occurs depends on the amount of growth that your child has remaining. Often times, the fractures that occur through the growth plate exit out through the ankle joint. If the broken pieces are very close to each other, our providers will try and treat the fracture without any surgery. Treatment of the fracture, however, will require frequent follow-up initially to ensure that the fracture pieces don’t move, and your child will have to remain initially in a cast above the knee before transitioning into a cast below the knee. Total time in a cast averages about 6 weeks. If the fractured fragments are separated too far from each other, then likely, your provider will recommend surgery to decrease the risk for pain and arthritis in the future. Similar to the other growth plate fractures, your provider will check x-ray in about 6 months after the injury to evaluate if the physis has been permanently damaged.