Low Speed Rear End Car Crashes: Facts and FAQs with Dr. Barry Matthisen, D.C.

The short answer is yes. Most whiplash injuries occur below 12 MPH. One of the reasons for this is that cars now are built stiffer and stronger due to the New Car Assessment Program of crashing into barriers. Most people are familiar with the 5 star rating system. When a low speed collision occurs, there is less “crush” to the vehicles structural integrity thus transferring  the energy of the crash to the occupant. At the Spine Research Institute of San Diego (SRISD), live human crash testing was conducted and one test recorded 12 G forces on a test subject’s head. The end result was no visible damage to either car.

To answer this we must first ask, what gets injured in the cervical spine during an event of a whiplash injury? Injuries occur to the facet joints, the surrounding ligaments, and cervical discs which are the some the main pain generators in the neck. Studies by world renown researchers by Manohar Panjabi and Paul Ivancic at Yale School of Medicine, showed facet joint and cervical spinal ligament damage can occur at the neck level at about 6.5 G forces and cervical disc damage around 8 G forces for a whiplash injury. So, a crash with no or little force can cause severe neck injuries to the anatomical structures listed above causing pain and dysfunction.

Panjabi, M., Ito, S., Pearson, A., & Ivancic, P. (2004). Injury Mechanisms of the Cervical Intervertebral Disc During Simulated Whiplash. SPINE, 29(11), 1217–1225. 

Back around 1990, insurers developed the MIST policy (minor impact, soft tissue) which used data to create treatment parameters, cost containment, Special Investigation Units (SIU), and litigation tactics to convince people that if there is minimal damage to the vehicles, there can’t be any damage to the occupants. They often downplay the injuries and state soft tissue injuries heal in 6-12 weeks. The MIST policy does concur with the peer reviewed literature. So, what are soft tissue injuries? Basically, injuries to anything that is not hard tissue, like bones. Soft tissue includes muscles, tendons, ligaments and cartilage lined joints, intervertebral discs, nerves, spinal cord, brain, and internal organs. Permanent impairments and disability can occur with damage to soft tissues. 

Statistics show that about one third of people in low speed, rear-end crashes get injured. Of those that are injured, only about half fully recover. The other half suffers chronic pain and the possibility of permanent disability. Permanent disability is around ten percent of those injured. There are risk factors that increase the risk of someone getting injured, both intrinsic and extrinsic factors. Intrinsic factors are factors that deal with the injured person, like pre-existing arthritis, advanced age, female sex, etc. Extrinsic factors are improper head restraint position, out of position occupant, type of vehicle getting rear-ended (like frame rail pick-up trucks and vans), unaware of impending crash, etc. The more risk factors you have, the more likely you are of  getting injured.

Have you been injured in a car accident and are seeking care? Have you had a whiplash injury and wish to be evaluated? We are a phone call away! Call 907-349-4212 and we will be happy to see you!

Barry Matthisen, D.C.