Mark Houston McFarland, D.C.

In the legal cases I have consulted in, often it is claimed that children cannot be injured in motor vehicle collisions, and therefore they do not require any treatment. To escalate this perspective, I have consulted in cases where the chiropractor treating such a child is accused of committing fraud, a crime. Occasionally, these cases will even progress to courtroom trial.

Pertaining to the causes of death of our children, the following statistics were compiled from the United States Centers for Disease Control (CDC) National Center for Health Statistics (NCHS).

In addition, the second leading cause for accidental death in children under 1 year of age was motor vehicle accident.

Based upon these statistics, it seems ludicrous to claim that children cannot be injured in motor vehicle crashes.

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Recently, a new-graduate chiropractor asked my advice regarding the management of an infant who had been injured in a motor vehicle collision. The insurance adjuster controlling the case stated: “our chiropractic consultant informs us that it is unlikely that an infant can be injured in a motor vehicle collision and therefore treatment of an infant after a motor vehicle collision is not likely to be reasonable or necessary.” Chiropractors that treat motor vehicle collision injuries, including those to children, are probably familiar with this attitude.

More than a decade ago, I had the opportunity to testify in a case in which a 7-year-old child and a 22-month-old toddler were injured in a motor vehicle collision. The children were treated successfully by a chiropractor. The mother of the children was adamant that the chiropractic care her children received was necessary for the improvement of their condition caused by the motor vehicle collision. Yet the case went to trial because of the attitude by the insurance company and their chiropractic paper reviewer that the children did not need the amount of care they received; or that the treating chiropractor’s records could not justify the care that he gave to the children.

One of the consequences of this trial was my generation of a chapter in a book, Pediatric Chiropractic, edited by Claudia Anrig and Greg Plaugher, Williams and Wilkins, 1998. The second edition of this book is due out later this year (2011). I did an extensive review of the literature pertaining to injuries to children from motor vehicle collisions, using more than 200 references. This article is a summary of some of the main principles of child injuries from motor vehicle collisions.

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Many of the concepts that pertain to adults in motor vehicle collisions also apply to children, including the basic principles of inertial acceleration/deceleration injuries, patient preparedness prior to impact, and rotation of the head or trunk prior to impact. Overall, studies indicate that the pattern of injury among children in motor vehicle collisions is similar to those of the general population.

However, injuries to children in motor vehicle collisions can be unique as a consequence of the following reasons:

1) Child safety seats.

2) The increased size of the child’s head as a proportion of the overall body mass.

3) The child's ability to be restrained while facing rearward.

4) The use of seat belts that are designed for adults.

5) The use of lap belts without shoulder harnesses.

6) The reduced height of the developing pediatric pelvis.

7) The underdevelopment of the pediatric anterior superior iliac spine.

8) The higher center of gravity for the pediatric body.

9) The diminished development and strength of various spinal musculoskeletal components.

10) The ability to sit on the lap of adults when traveling in a vehicle.

11) The probability that a child injured in a motor vehicle collision is unprepared for the collision, or caught by surprise.

12) The more unfavorable head diameter to neck diameter ratio, as compared to adults.

I believe that each aspect (above) of this uniqueness regarding children injury during motor vehicle collisions should be understood by the health care provider so that he/she can better explain the appropriateness of treatment given to these injured children. Specifically, I believe that the health care provider should:

1) Understand the biomechanical uniqueness of injury for each age group of children involved in a motor vehicle collision.

2) Learn how to examine and document pediatric trauma, including daily charting.

3) Become proficient at the treatment management of injuries in such small bodies.

I will briefly review these concepts below. A more detailed explanation

with graphics and references is available in the next edition of Chiropractic Pediatrics, edited by Anrig and Plaugher, 2011.

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Anthropometric Variables For Children

Head Size

The increased size of the pediatric head as a proportion of the overall body mass influences the location and type of injuries sustained by children involved in a motor vehicle collision. At birth the head is proportionately larger and accounts for approximately 25% of the body length as compared with 15% in the adult. Consequently in motor vehicle collisions it is the head and cervical spine of the newborn that is most likely to be injured in a motor vehicle collision.

Toddlers up to 3 years of age continue to have disproportionately large head size and higher centers of gravity, and, therefore, also tend to sustain head injuries. Rear facing child safety seats tend to restrict forward head movement and prevent young heads from striking the interior of the vehicle.

Pelvic Height

The reduced height of the developing pediatric pelvis predisposes children to unique injury. Every anatomical part of children is reduced in size as compared to the adult, including the height of their pelvis. This reduced height increases the probability for a lap belt to slip over the top of the brim of the pelvis during a motor vehicle collision, resulting in more serious abdominal visceral and lumbar spine fulcrum injuries.

Anterior Superior Iliac Spine

The underdevelopment of the pediatric anterior superior iliac spine increases the probability for unique injury for young patients. Children younger than 10 years of age have less development of the anterior superior iliac spine as compared to the adult. This increases the probability for a lap belt to slip over the top of the brim of the pelvis during a motor vehicle collision, resulting in more serious abdominal visceral and lumbar spine fulcrum injuries.

Center of Gravity

The higher center of gravity for the pediatric body changes the nature and location of injury. Children have a relatively higher center of gravity and a greater tendency for the lap belt to ride cephalad to across the abdomen as compared to adults. This elevated position allows the child to submarine forward under the belt, increasing injury to the abdomen and/or the spine.

4-9 year olds have a relatively lower center of gravity in contrast to infants and toddlers, closer to the umbilicus but still above the lap belt. Yet the iliac crests are underdeveloped in this age group and the lap belt tends to slip up over the bony pelvis and onto the abdomen. With a rapid deceleration event, with a greater proportion of body mass above the lap belt and with the lap belt already in contact with the abdomen, "jackknifing" occurs with compression and injury of abdominal viscera. The hallmark indicator of abdominal viscera and mid-lumbar spine injury is abdominal or flank ecchymosis.

Tissue Strength

The diminished development and strength of various spinal musculoskeletal components increases the probability of significant tissue injury in children. Children have less well developed muscle and connective tissue, which increases probabilities for spinal joint and neurological injury.

Submarining:

Primarily because of the shortness of their pelvis and under development of their anterior superior iliac spine, children, especially those between ages 4-9, have a higher probability of having their torso slip under the lap belt during a motor vehicle collision thus sustaining associated injuries. This is termed submarining. 10-14 year olds have a better developed anterior superior iliac spine, a “taller” pelvis, and consequently experience submarining less often.

Child on Adult Lap

A parent should never hold an infant or child on their lap while riding in a motor vehicle. In a front-end collision at 25 miles per hour at impact, the forces on the baby may reach 20 G. If the weight of the baby is 7.5 pounds its effective weight raises to 150 pounds (7.5 lb X 20 G = 150 lb). If the weight of the child is 25 pounds its effective weight raises to 500 pounds (25 lb X 20 G = 500 lb). It is impossible for the adult to hold the baby under those circumstances. To hold a 10-pound infant at 30 mph the adult strength required would be roughly that needed to lift 300 pounds one foot off the ground.

If the adult holder is also unrestrained, their body may crush the baby against the dashboard or the back of the front seat. When the adult is not restrained, the infant is crushed by a force equal to the mass of the adult multiplied by the square of the speed and divided by two. When the child is held in the arms of an adult and both are not using belt restraints, the weight of the adult is added to the child's weight as they are thrown forward. The adult will crush the child with an incredible force.

Studies indicate that many infants under the age of one travel in cars while being carried on adult laps.

Unrestrained Children

Careful observation of anthropomorphic video graphically shows that even though the principles of inertia apply to children, they are different, especially when the child is less than 40 lbs. When young children are unrestrained, their entire body functions as a single piece of inertial mass, and will fly through the air during motor vehicle collisions, becoming “human projectiles.” Injuries include crashing through the glass and being thrown from the vehicle, as well as colliding with the inside of the vehicle. In a moving vehicle that is stopped suddenly by an impact, an unrestrained smaller child will continue to move at the original vehicle speed until stopped by the interior of the vehicle. Even in low speed collisions an unrestrained child becomes a human projectile.

Studies indicate that children run more risk of injury or death traveling unrestrained in a vehicle than by being hit by a vehicle as a pedestrian. It is estimated that disabling to fatal injuries to these children would decrease by 78-91% if the child was using a restraint system during motor vehicle collisions. It is estimated that 49% of child passenger deaths from motor vehicle collisions could have been prevented with appropriate child restraint use. Children not in safety restraint devices are 11 times more likely to die in a motor vehicle collision than children placed in restraints. Unrestrained children are three times more likely to sustain a brain injury than restrained children.

Children in Restraints

Reduction In Injuries:

The April 2011 edition of the journal Pediatrics published the policy recommendations of the Committee on Injury, Violence, and Poison Prevention pertaining to Child Passenger Safety in motor vehicle collisions. This project used twenty-two expert collaborators. The abstract of their work project includes:

Child passenger safety has dramatically evolved over the past decade; however, motor vehicle crashes continue to be the leading cause of death of children 4 years and older.

This policy statement provides 4 evidence-based recommendations for best practices in the choice of a child restraint system to optimize safety in passenger vehicles for children from birth through adolescence:

1) Rear-facing car safety seats for most infants up to 2 years of age.

2) Forward-facing car safety seats for most children through 4 years of age.

3) Belt-positioning booster seats for most children through 8 years of age.

4) Lap-and-shoulder seat belts for all who have outgrown booster seats.

In addition, a fifth evidence-based recommendation is for all children younger than 13 years to ride in the rear seats of vehicles.

It is important to note that every transition is associated with some decrease in protection; therefore, parents should be encouraged to delay these transitions for as long as possible.

The American Academy of Pediatrics urges all pediatricians to know and promote these recommendations as part of child passenger safety anticipatory guidance at every health-supervision visit.

Injuries from Restraints

The leading cause of morbidity and mortality in children is trauma and the most frequent mechanism is motor vehicle collisions. Restraining children decreases their chance of injury or death. Seat belts prevent ejections and reduce impact between the child and the interior of the vehicle. Yet serious injury can still occur even when restraining belts are used because the belts themselves can cause harm and injury. The belt systems have their own unique pattern of injury as they change the distribution of forces, especially to the abdominal viscera in a deceleration event. Violent hyperflexion of the child's torso over the lap belt applies flexion-distraction forces to the spine. Submarining, or slipping of the child underneath the lap belt can occur and predispose the child to additional abdominal trauma. Children at maximum risk are those too large to be in a safety seat yet too small for the available restraint belt system which are designed for adults (transition age from above). In spite of the drawbacks, adult seat belts are recommended over no restraint at all as they reduce injury and death.

Seat belts may cause injuries from the neck to the pelvis. The probability of seat belt induced injuries increases when the restraint device is not used properly. Common errors in restraint use include:

• The child is placed in a restraint not designed for his/her size or weight.
• The child restraint is not properly anchored to the vehicle.
• The restraint is not properly applied to the child.

Children and Lap Belt Injuries

Lap belt injuries are usually associated with children between ages 4-9, as these children are too large to use restraint seats and are too small to safely use adult lap belts. Children in this age group have special and unique anatomical characteristics that increase their vulnerability to lap belt injuries. Children have relatively larger heads and less well developed spinal musculature than adults, putting children at greater risk of hyperflexion injuries. The immature pelvis is more likely to slip below the seat belt creating fulcrum load injuries to the abdomen.

Conventional lap restraints do not properly restrain or protect children because the anterior superior iliac spine is under developed in this population. The belt rides up onto the abdomen and chest and may itself cause significant injury. If the vehicle rapidly decelerates the child may whip forward with increased force than an adult because of the child's higher center of gravity and greater body mass above the waist. Children have greater probability of lap belt induced abdominal and spinal injuries because of their greater percentage of body mass above the umbilicus, the poorly developed anterior superior iliac spine, and the frequent lack or misuse of the shoulder harness for children. Children lap belt syndrome injuries typically have an abrasion or contusion across the abdomen, created by the lap belt. These children may suffer from fracture, dislocations, neurologic damage, and significant intra-abdominal injuries.

A 1986 report from the National Transportation Safety Board suggested that the use of rear seat lap belts may be more harmful than no seat belt use at all for children, stating: “In many cases, the lap belts induced severe to fatal injuries that probably would not have occurred if the lap belts had not been worn.” Although rear seat lap belts do not meet the special needs of children, most agree that restraining a child with a lap belt is preferable to having no restraint at all.

Children and Shoulder Harness Injury

Children between ages 4-9 are generally too large to use a restraint seat and yet are too small to safely use an adult shoulder harness restraint. If such children use an improperly fitting adult shoulder harness across their neck or face, serious and fatal injuries have been reported. As the neck / face position for the shoulder harness is uncomfortable for these children, they often will modify its placement by putting the shoulder harness behind their back or under their arm.

Infants and Air Bags

The deployment of air bags occurs at high velocity and creates a serious hazard for children as a result of “bag slap.” The air bag mushrooms out in a fraction of a second, reaching speeds up to 200 mph. Because the rear of the infant child restraint seat is close to the air bag compartment, it will receive a tremendous force from air bag deployment, resulting in serious head injuries to the child. Therefore, rear-facing infant seats should be used only in the back seat of vehicles that have front passenger air bags.

Types of Injuries to Children

As noted, both injury and death are frequently reported in children who are involved in motor vehicle crashes. Injury risk and seriousness is greatest when the child is unrestrained or improperly restrained. However, serious injury and death routinely occurs in properly restrained children. The injuries best documented in the literature include:

Brain Injury

Facial Fractures

Cervical Spine Injuries

Upper Cervical Injury

Cervical Disc Injury

Apophysis (growth center)Injury

Cervical Spinal Cord Injury

The Gamete of Soft Tissue Injuries

Seat Belt Syndrome Abdominal Injuries

Psychological Injury

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Summary

Children are injured in motor vehicle collisions, and it is not a small problem; rather, it is a huge problem. Motor vehicle collisions have consistently proven to be the number one reason for both mortality and morbidity in children younger than 25 years of age.

The bodies of children younger than one year of age function as a single piece of inertial mass during motor vehicle collisions. Children in this age group have a proportionately larger head size as compared to overall body mass. Consequently, when they are unrestrained during a motor vehicle collision, they tend to “lead” with their head. Their heads and bodies will collide with the interior of the vehicle, and ejections of their bodies are known to occur. Such unrestrained children sustain serious head, brain, and cervical spinal cord injuries, leading to death and significant lifelong disabilities.

When children younger than one year of age are restrained in a child restraint seat and that child restraint seat is not securely attached to the vehicle seat with the appropriate adult restraint belt, the child's body and the restraint seat together will function as a single piece of inertial mass. Once again the child will sustain serious head and brain injuries. Not securing the child safety seat to the vehicle is considered to be misuse of the safety device.

When children younger than one year of age are properly restrained in a forward facing child safety seat, and that child safety seat is properly secured to the vehicle with the adult restraint belt, serious head, brain, and cervical spinal cord injuries are largely avoided. Yet, in this forward facing position the properly restrained child has increased vulnerability to cervical spine injury, especially in frontal impacts. This is because the restraints immobilize the child's body, yet their head remains moveable. With this young child's proportionately larger head size as compared to overall body mass, and with the child's poorly developed strength of the cervical spine musculoskeletal tissues, significant cervical spine soft tissues occur.

Most serious injuries to restrained children younger than one year of age occur during a frontal impact collision. These serious injuries can be reduced by placing the child restraint seat in a rearward facing direction, and then properly securing this child restraint seat to the vehicle using the adult restraint belts. Serious injuries are reduced as the forces of the frontal impact are dispersed over a broader surface area of the child; over the back of the skull, the thoracic cage, and the pelvis. There is no doubt that a child of this age group who is properly restrained in the rearward facing position has the best chance of avoiding injury in a motor vehicle collision, and especially in serious frontal impact collisions.

When children younger than one year of age are restrained in a child safety seat that is properly secured to the vehicle by the adult belt, but the crotch strap of the child safety seat is not properly attached, the child's body will “submarine” under the waist strap, catching the child under the chin. The results are serious cervical spine injury, including fracture of the odontoid process or a bipedicular (hangman's) fracture of C2. An adult must always properly secure the crotch strap portion of the child restraint seat for children in this age group.

Children younger than one year of age should not be restrained in a child safety seat in the rearward facing position in the front seat of a vehicle that has a passenger side air bag. In this position, the closeness of the child to a rapidly outwardly exploding air bag can launch the safety seat and child at an extremely high velocity, resulting in serious head and brain injury.

Children between 1 - 4 years of age are similar to children younger than age one in that their heads are proportionately larger as compared to overall body mass, the strength of their musculoskeletal spinal tissues are not as developed as those of the adult. When they are unrestrained they tend to “lead” with their heads sustaining serious head, brain, and cervical spinal cord injuries after colliding with the interior of the vehicle, and are at risk of ejection. Recent retrospective statistical studies show that the children in this age group are least injured when they are properly restrained in a child safety seat facing the rearward direction. When children in this age group are properly restrained and facing the forward direction, they sustain significant cervical spine soft tissue injury during frontal collisions. Contrary to common practice, it is recommended that children remain in child restraint seats facing the rearward position for a long as possible as they age, ideally to approximately age 4.

Caution should be used when restraining children between 1- 4 years of age in an adult lap belt. The pelvis of children in this age group is much shorter in height, and the anterior superior iliac spine is grossly underdeveloped as compared to that of the adult, increasing the tendency for the lap belt to slip up over the top of the pelvis rim and to be in contact with the abdomen and its contents. Because of the shorter stature of these children, in a frontal impact their face or chest will not collide with the dashboard or with the seat in front of them. This results in a serious rapid flexion of the child's torso around the adult lap belt, or “jackknifing.” Serious and fatal abdominal viscera and mid lumbar spinal injuries result.

Children between ages 4 - 9 years have the greatest difficulty with motor vehicle collision safety. Children in this age group face forward nearly always and are restrained in the adult seat belt. Unfortunately, adult seat belts do not meet the special needs of this group of children. Often they are riding in the rear seat of the vehicle, and there are still many vehicles that do not have shoulder harness restraints available for rear seat passengers. As the developing pelvis remains short in height with an underdeveloped anterior superior iliac spine in this age group, it is once again common for the adult lap belt restraint to slip over the rim of the pelvis and to come into contact with the abdomen and its contents. The center of gravity for these children is higher as compared to that of the adult, superior to the lap belt. This proportionately increases the fulcrum stress above the lap belt in a frontal impact or during a rebound flexion following a rear impact. Again, this results in serious injuries to the abdominal viscera and mid lumbar spine, including Chance fractures. Depending on the stature of these children, their face/head may impact the dashboard or the seat in front of them, resulting in significant face, head, brain, and cervical spinal cord injuries. It is, therefore, recommended that whenever possible, children of this age group should be restrained in a lap belt shoulder belt combination.

Children between ages 4 - 9 years also have unique problems when using the recommended adult lap belt with shoulder harness combination. Because of their short stature, the shoulder harness does not fit their body adequately. For many children in this age group, the shoulder harness will cut across their cervical spine or face rather than their chest. When left in this position, the shoulder harness can cause serious and fatal cervical spine and facial injuries. Also, because of the uncomfortable annoyance of the shoulder belt crossing the neck or face, many children of this age group will simply place the shoulder strap behind their back, rendering them susceptible to the lap belt injuries noted above. Other children will place the shoulder harness under the arm. This position is also quite dangerous, as the thoracic cage is not capable of handling the forces of a frontal collision during this age of skeletal maturation that are generated by the shoulder harness. The stresses imparted to the child can seriously injure the thoracic cage, including imparting cardiac and pulmonary trauma. The proper shoulder harness placement for this age is across the chest, over the clavicle, but remaining off the cervical spine and face. This is best accomplished by using a booster seat that effectively increases the height of the child, or by using a device that lowers the shoulder harness away from the face and neck and into the proper position and secures it in place by attaching to the lap belt.

Very young children cannot communicate to their parents or health care providers the location or nature of their injuries. Even non-life threatening injuries in children should be documented and properly managed.

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