Low-Speed Collisions, Soft Tissue Damage, and the Curve of Your Neck

It is one of the most common things we hear. There was barely a scratch on the car, so the adjuster suggested nobody could have been hurt. It sounds like common sense. It is also contradicted by the engineering.

Bumpers are built to hide damage

Federal bumper standards require passenger car bumpers to withstand low-speed impacts without damage to the vehicle. That is the design goal, written into regulation. A bumper system that meets it has done its job when the car looks fine afterward.

Here is the part that surprises people. Energy has to go somewhere. When a bumper crushes, it absorbs energy in the process of deforming. When a bumper does not crush, that energy is transferred instead into moving the vehicle, and the vehicle moves the seat, and the seat moves you. A stiffer, more damage-resistant bumper can produce a higher acceleration of the occupant than a bumper that crumples.

This is not a fringe position. Crash research going back to the controlled rear-end collision studies of the 1950s, and reinforced by human volunteer testing and engineering analyses published through the Society of Automotive Engineers, has repeatedly found that vehicle damage is a poor predictor of occupant injury.

The neck has a curve, and it has a job

Viewed from the side, a healthy cervical spine curves gently forward. That curve is called lordosis, and it is not decorative. It positions the vertebral bodies so that compressive load passes through them efficiently and shares that load with the joints at the back of the spine.

After a collision, that curve frequently flattens or reverses. In the acute phase some of this is muscle guarding, and it resolves as the spasm settles. But comparative radiographic studies of patients with chronic whiplash symptoms have found altered sagittal configuration persisting well beyond the point where spasm would explain it. In those cases the supporting ligaments have been stretched and the segment no longer holds its position.

Why the curve matters over years

Biomechanical modeling of the cervical spine has shown that when the normal lordosis is replaced by a straightened or buckled configuration, stresses within the vertebral bodies rise substantially compared with a lordotic spine carrying the same load. Bone and cartilage respond to sustained abnormal loading by remodeling, and in the spine that remodeling looks like disc height loss, bone spur formation, and facet joint wear.

Clinical studies correlating cervical spine geometry with degenerative disease have found the association you would expect from that model. Work on the cervical spine after fusion has also shown that segments left in a kyphotic alignment degenerate faster at adjacent levels than segments left in normal alignment.

The practical implication is that the accident you had in your thirties can express itself in your fifties as arthritis at the levels that were injured.

What we do with this

We image the cervical spine in the standing lateral position and measure the curve rather than eyeballing it, so we have a number to work from and to compare against later. Treatment aims at restoring segmental motion and supporting the curve while the injured tissue is still remodeling, which is a window measured in weeks, not years.

If you were told your accident was too minor to have hurt you, and you do not feel right, get examined. Call (725) 255-7333. Henderson, southwest Las Vegas, and North Las Vegas.