Left femoral lengthening procedure with intramedullary lengthening nail device inserted
16yo with severe valgus and 7cm LLD after traumatic growth arrest to distal Left femur
Far Left: MRI showing partial central growth arrest in distal femur. Below: CT scans showing central growth arrest of proximal tibia, and % calculation using CT program.
by Matthew Harris MD, MBA
Growth arrest can occur as a result of trauma, metabolic disorders, malnutrition and underlying skeletal dysplasias. Any disruption or injury to the growth plate (aka physis) in a person who is still growing frequently leads to deformity and shortening in that bone. Frequently, we encounter growth plates that have been damaged by trauma, such as what happens during certain fractures. It is possible that a fracture can break through the growth plate in such a way that the body is able to heal itself, and no long-term adverse outcomes will result. The Salter-Harris Classification (seen below) is used to categorize fractures that involve the growth plate. This underlies the importance of promptly treating fractures that involve the physis, and lining those bones back up in the best way possible to ensure the lowest chance that the growth plate will sustain permanent damage.
We are not always so fortunate though. Many times when such injuries are sustained, your child's growth plate suffers permanent damage, regardless of whether or not it is properly treated, and this can lead to part, or even the entire growth plate closing. When only part of the growth plate closes, the healthy growth plate that remains continues to grow normally. Growth plates are designed to grow evenly, but when only one side of it is working properly, a bone will actually begin to grow crooked. This is what we would refer to as a partial growth arrest that leads to a developmental deformity. In comparison, when a growth plate closes entirely, your child will be less likely to develop an angular deformity per se, but instead he or she will develop a limb length discrepancy (LLD). In other words, the bone with the complete growth arrest will be shorter than it was originally intended to be.
The severity of the growth arrest depends not only on how much growth plate is damaged, but also, the age of your child at the time of injury. For example, a 6 year old boy who fractures his femur near the knee, and permanently damages his entire growth plate so that it will never grow again can be expected to have a 9 cm leg length discrepancy (LLD) by the time he is finished growing. We know this because that particular growth plate grows approximately 9 mm / year until the age of 16 in boys. 9 cm is equivalent to over 3 1/2 inches. A 16 year old boy with a 3 1/2 inch limb length discrepancy (LLD) that was not treated would walk with a significant limp, and be forced to wear shoes with specially made thick soles to make up for the difference. This of course, is a very awkward and frustrating condition for any 16 year old to have to endure, and this is to say nothing of the long-term risk of developing low back pain, hip and knee pain, and early arthritis.
Diagnosing Growth Arrest: Following a suspected injury to your child's growth plate, we will need to arrange long-term
followup so that XRays can be repeated on a regular basis. The damage is rarely ever known or appreciated at the time of initial injury. Instead, the damage leads to changes which take a period of time to evolve, and it is not uncommon to need to follow your child for several years after a growth plate injury before we know the full extent of damage. In addition to XRays, we will often order an MRI or a CT scan when we know that there is permanent damage. These tests allow us to accurately quantify the %-age of the growth plate that prematurely closes off, and this information guides our treatment. We often refer to these areas where the growth plate has closed as physeal bars.
Treating Growth Arrest: The treatment of this condition depends on the severity of the damage, presence of resulting deformities and the age of your child. There are a number of treatment options depending on these factors. For instance, with some cases treatment could consist of going in to surgically remove the damaged growth plate so as to remove the tethering effect that it creates, and thereby allow the healthy portion to continue growing with less chance of an angular deformity developing. Alternatively, we can leave the damaged growth plate where it is, and intentionally remove the healthy portion so that the entire physis effectively stops growing, or at the very least, contain it so that it will not grow any further (hemi-epiphysiodesis). While this will ensure that the bone will be shorter, it will also ensure that it will remain a straight and otherwise functional bone which is needed to healthy joint motion.
The goals in treating growth arrest are to minimize angular deformity and minimize limb length discrepancy. This can be accomplished by any of the treatments mentioned above, as well as, more extensive surgeries. In the case where one femur is certain to be shorter than the opposite because of a growth arrest, occasionally we may recommend closing the growth plate from the healthy femur (epiphysiodesis), so that effectively both growth plates stop growing and therefore the femurs will be the same length when your child finishes growing. For children who were going to be very tall already, losing an inch or two is not something that is devastating from a practical standpoint. However, it is entirely reasonable that a child or his/her parent wants to be as absolutely tall as they were intended to be. In these cases, we can lengthen the bone in order to catch it up with the opposite side. Technology has advanced significantly in the last several years, and depending on the bone in question, we can offer any number of minimally invasive ways to lengthen a short bone. There are also techniques and technologies to address any angular deformities that have developed as well, perhaps due to a partial growth arrest.
The case below illustrates some of the more complex procedures and techniques that are sometimes required to address an underlying angular deformity, as well as, a significant limb length discrepancy as seen in this 16 year old boy. This is meant to serve as an illustrative purpose only, and by no means is meant to represent a standard treatment for every patient with a traumatic growth arrest.