Please Note: I am writing this Blog to give you a basic understand of how, in my opinion, this condition should be addressed. Please note: My opinions are not necessarily the opinions of Active Release Techniques, but I am sure if Dr. Michael Leahy (the founder/developer/owner of ART) would like to correct me on a few points, he will drop me a note. In fact I would love to hear feedback on this subject from a wide variety of patients and practitioners in many different fields.
Now that I have given you my “Disclaimer” I will get into the important aspects of this condition.
The first factor to consider is that hyper-extension, hyper-flexion injuries occur in an extremely short period of time. Most of these injuries occur in about one-quarter of a second. This means that the occupants of a vehicle which is struck from behind do not have time to react to the accident. Keep this time-frame in mind as we cover some of the actions that occur.
Let us start with the onset of a standard rear-end collision. Let us consider what happens from the perspective of the driver of the vehicle that was hit from behind. On initial impact where the vehicle in the rear hits the car in front; The force of impact begins to move the front vehicle forward. Since the seat of the car is attached to its frame, the driver’s seat moves forward with the car. But the driver is not attached to the frame of the car, and he/she continues to remain in a fixed position; this is due to inertia. Physics defines inertia as “the tendency of a body to resist acceleration.” Keep in mind, all of this is occurring within milliseconds.
Then, within a faction of a second, the car seat is pushed into the driver’s lower and mid back. This rapid forward acceleration also pushes the lower part of the drivers neck forward (lower cervical spine). This has the effect of straightening out the normal curve in the driver’s neck (the lordotic curve) and the curve in the driver’s mid back (the kypotic curve). This creates an abnormal S shaped curve in their cervical spine (neck).
A considerable amount of damage can be done during this phase.
o Normally, neck motion is the result of multiple vertebral joints, each of which contribute only a few degrees of motion to an action. Therefore movements like neck extension are made up of the summation of multiple vertebra each adding small degrees of motion to produce the total action.
o When the neck is in this abnormal S-shaped position, the joints of the neck (facet joints) are forced past what is consider their normal physiological range-of-motion limit. This excessive motion causes damage to the area around the spinal joints (facet joints). This damage can include: facet capsule ligament tearing, bony impingements, and intra-articular (within the joint) hemorrhages. The degree of joint damage depends on the severity of collision.
Chronic whiplash and whiplash-associated disorders: An evidence-based approach Journal of the American Academy of Orthopedic Surgeons October 2007;15(10):596-606 Schofferman J, Bogduk N, Slosar P.
See Part 2 – Resolving Whiplash Injuries with Active Release for a continuation of the biomechanics of a whiplash accident and a review of commonly injured structures.
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