EVOLUTION; SAFETY FIRST, PART II
by Dr. Ken
The football helmet, although decorative and symbolic of a team's city or state of origin, a time-honored tradition held dear by that team, or an immediate recognizable call to arms for the team's supporters, was developed, and meant to protect the player. A brief review of the injury mechanism that produces head and neck injuries might shed light on the various changes undergone in helmet safety development. We hope our loyal readers aren't put off by what at first may seem like "technical" terms as this brief summary will be easily understandable and give a much greater appreciation for the protective nature of football head gear.
The most obvious and frequent injuries in football's "early days" were facial cuts and bruises. Going without a helmet, or wearing the early model leather ones without a facemask allowed the old-school player the privilege of showing off his scrapes, cuts, bruises and often lost teeth for weeks after the conclusion of his season. Blocking and tackling procedures followed the relatively flimsy construction of the helmet with the shoulder block being dominant. Once the plastic helmet became more widely used, tackling techniques especially reflected the change in headgear. Headfirst contact became more widely seen, in part because the player believed himself to be "safer" from injury. With the change in rules which called for mandatory use of head gear and a facemask, many were quite eager to literally as well as figuratively "stick their heads" into their opponents.
As injuries to the head and neck area grew, a study was undertaken to determine how frequently serious head or neck injuries occurred. To the present day, every study has indicated that throughout the "modern" history of the sport of football, and we can arbitrarily date that from 1950, more head and neck injuries have occurred at the high school as opposed to the college or pro levels. Speculation can be tended including a lack of physical maturity with an accompanying decrease in muscular strength of the supporting tissues, less sophisticated playing techniques, and unsafe coaching practices. However, the legitimate scientific studies and literature reviews have clearly indicated that there is a definite cause and effect which explains traumatic, catastrophic on-the-field injury.
The neck area is orthopedically referred to as the CERVICAL SPINE. It includes the vertebrae or bones in the neck, and for the purposes of our discussion, the intervertebral discs (pads of cartilage which sit between and separate one vertebra from another), the ligaments which serve as rubber bands which hold one or more bones to each other, and the muscles which overlie the bones and connective tissue. The spine, or the actual bones when stacked upon each other, have the primary purpose of allowing the spinal cord to run through it. When they are stacked up, there is a canal through the middle, a tunnel so to speak, that runs from the brain to the rest of the body, allowing nervous tissues to send signals to the muscles, skin, and organs so that they can function and move properly, while having signals from all of the body parts run back towards, and into the brain so that the body knows through its many senses, what's going on around it. Any interruption in those signals can cause a loss of function or sensation. The cervical spine area is of utmost importance because if there is an injury that interrupts the flow of nervous tissue information, everything or almost everything from below that point is affected. A spinal cord injury that interrupts the normal flow of information in either direction from or to the brain, presents obvious problems and this is what is referred to as a catastrophic injury. Unfortunately, the sport of football has had many of these.
The exact "what happens," or mechanism of injury to the neck and/or head area was a matter of speculation for many years. Neurologists and orthopedists could not agree on which type of injuries were more serious, the frequency of these injuries, and the best way to approach treatment. As more resources were devoted to proper studies after World War II, and accurate records could be maintained, certain trends became obvious. Definitive studies that covered the years 1959-1963 were compared to injury statistics from 1971-1975 and this became the standard which instituted the many changes in the helmet industry. In a comparison of these time periods, it was discovered that intracranial hemorrhages and intracranial deaths (injuries that occurred due to bleeding inside of the head or brain) decreased by 66% but that there was an increase in craniocervical death of 42%. In summary, this meant that in an approximate twenty year period, there was a marked decrease in severe head injuries while death due to cervical spine/neck injuries jumped considerably. In "the old days," it was assumed that any death on the football field resulted from direct head injury, a blow that was so hard and so severe that it damaged the brain tissue and/or the vessels of the brain. The more recent studies indicated that while these types of injury had declined, the incidence of neck related injuries had resulted in a significant increase overall and in both death and para- and quadriplegia (loss of the use of some or both limbs and much of the trunk musculature and function).
How do these occur? We know that our brain is responsible for many vital functions. The spinal cord and its accompanying nerves are responsible for distributing the brain's signals to the body while bringing the body's information back to the brain. We instinctively know we have to protect or head and neck as all of these vital structures pass through the neck area. The primary mechanism or cause that produces severed cervical spine injury is called AXIAL LOADING. This is the application of a vertical load onto the spine or top of the head so that the compressive force is directed downward. We have a number of "natural" safeguards against this type of injury, one of them being the shape of the spine. If we viewed a normal cervical spine from the side, it would have a gently sloping C-shaped curve. The open part of the "C" would be facing the back of the body. Each vertebra sits on top of the one below it, with a disc, or pad of cartilage, separating them. This configuration, and the discs, serve to efficiently absorb shock and compressive force. What anatomists term "controlled motion" of the cervical spine, movement of one bone on top of the other as it absorbs and then dissipates force, is the body's way of handling force that is placed vertically upon it. If we dropped someone directly on their head, or dropped a heavy object directly onto their head, it is the shape of the spine and the way the bones in the neck align, that allows the compressive force to "pass through" the structures without doing damage. The discs serve as mini-shock absorbers and the musculature of the neck and upper back region also take the force and deliver it away from the vital structures of the neck. If the forces are not correctly or efficiently dissipated, and they then "travel" along the vertical axis of the spine, there is potential for injury.
If we use the expression that a whole is greater, or in this case, stronger than the sum of its parts, it provides a good and understandable explanation of the protective work that the elements of the cervical spine do. The C-shaped curve, properly called a LORDOTIC CURVE gives the neck area an efficient way to absorb, deflect, and dissipate force. If the curve is reduced so that the spine appears to be straight on an X-ray, it no longer has the same ability to absorb vertically applied force. In fact, instead of behaving as a strong "whole," the cervical spine then acts as if it is in segmented pieces. In effect, each bone in the neck or vertebra is on its own. Where the entire, properly aligned cervical spine might be able to absorb a great deal of force, each individual vertebra cannot. If the force is not then absorbed and dissipated by the discs and musculature, it "goes" directly into the vertebrae. If the force is great enough to exceed the structural integrity of the bone or bones, they can buckle and break, or fracture. A fracture might drive a piece of bone into the spinal cord, injuring or severing it. It might disrupt the entire cervical spine so that a vertebra is driven into the chord. The spine will deform and with continued application of vertical force, buckle and break. In either case, common sense dictates that once the spinal cord is injured, the resultant disabilities can be life threatening and permanent.
The other major cause of cervical injury will be discussed in our next installment. The way in which a football player blocks or tackles, and the resulting position of the spine, can easily predict the end result as it will affect the bones, discs, and muscles in the neck area. The rules changes that came about in order to prevent traumatic, serious injury, and the role of the helmet in all of this will be upcoming. Check back on HELMET HUT often.