Ok, I know, today was supposed to be part one of my five part series Neck Braces: Why (insert brand here) is the best. Holy crap have I learned a lot during my research. While working on these stories I realized that there is a lot of information to take in. I decided that it is important that everyone understands the information below before reading Neck Braces: Why (insert brand here) is the best. There are a lot of terms that come up in these stories that I feel are best off defined in one place rather than over and over again in each story. If you have no idea what I’m talking about check out Neck Braces: Why Each Brand is the Best for a quick rundown.
What injury causing situations are motocross neck braces designed to help prevent?
Leatt has the most complete information on their site, here are their definitions:
- Hyperflexion – over-bending of the head in a forward direction
- Hyperextension – over-bending of the head in a rearward direction
- Lateral Hyperflexion – over-bending of the head to one side
- Posterior Hypertranslation – extreme movement of head and helmet, rearward on the neck
- Coupled Axial Loading– helps prevent axial loading only when the axial forces act in combination with other mechanisms
- Axial Loading is when the neck is partially flexed aligning the cervical vertebrae in a straight column. lf a force is then applied to the top of the head, the neck is unable to handle the impact causing cervical spine compression, which results in fracture or dislocation. Definition from John Heck in this article.
If you’re interested, or want to see how these are defined by an uninvolved party, here are some definitions from the Medical Dictionary:
- Hyperflexion – flexion of a limb or part beyond the normal limit
- Hyperextension – movement at a joint to a position beyond the joint’s normal maximum extension
What is the most common cause of neck injury to MX riders?
From what I’ve read in Leatt’s Whitepaper and Alpinestars’ Safety Critical Information guide (users guide) it seems the most common cause of catastrophic neck injury in motocross is axial loading. This is very hard to prevent with a neck brace due to the position your head is in to align your cervical vertebrae. Most neck brace manufacturers say that no current neck brace can protect against this sort of injury (more info on this below).
Which injury causing situations are not possible for motocross neck braces to prevent?
No neck brace can prevent neck injuries in all situations, there are just too many variables, but axial loading seems to be a particularly tricky situation to prevent.
In Leatt’s FAQ section Leatt clearly states that their (or any other brand’s) brace cannot prevent pure axial loading.
Pure axial loading cannot be prevented by any currently available brace. Achieving this will render an impractical device, as it would inhibit safe riding. The Leatt-Brace® was designed to help reduce axial forces when acting in combination with other forces (bending moment and shear forces). This happens in most impact scenarios when the head goes into hyperextension (over-bending of the head in rearward direction) or hyperflexion (over-bending of the head in forward direction). The brace absorbs and reduces forces once the head has moved out of the original line of impact and limits excessive range of motion of the neck.
Alpinestars makes a similar comment about axial loading in Dirt Rider’s The Neck Brace – Should You Wear One?
The damage is caused between five and eight milliseconds of the initial head impact, and [damage] is especially likely when the impact occurs within the cone of vulnerability. In the course of the research that Alpinestars undertook, the ‘Cone of Vulnerability’ defines a virtual space starting from at the top of C1 and extending upwards at a 15-degree angle through to the top of the head. If the impact occurs within this cone-shaped space with the rider’s torso following, the load is transferred almost instantaneously and very directly to the neck. Inside this time period the head does not move at all and therefore is not in contact with the support surface, so no alternative load path exists.
How are motocross neck braces supposed to help prevent injuries?
Leatt and Alpinestars neck braces are designed to provide an alternate load path and direct energy away from your neck. It is important to note that as of late Leatt and Alpinestars have begun to make a point to let people know that their braces are designed to direct this energy away from the sternum and spine and into the chest and back muscles as this was a big misconception and knock on their designs in the past.
Both Atlas and EVS talk a lot about absorbing energy through the flexibility that their neck braces are designed with before distributing the energy through other parts of your body.
What is CE 89/686/EEC Category II?
You will see many neck braces sporting this certification, but what does it mean? Currently there aren’t any set standards for neck braces, so this is the best available. This standard is for personal protective equipment against medium risk. It seems to involve more of an examination than actual testing of a safety device. To get the full story you can read the entire CE directive here.
Anyhow, sorry for the delay, come back Wednesday 4/16/14 for Neck Braces: Why the Alpinestars BNS is Best. Future stories in this series will be available here.