The facet joints are the posterior joints of the neck. To describe the vertebra in the spine, I often use the tricycle analogy. The big body of the vertebra is the big front wheel of the tricycle with the discs sandwiched in between. The facet joints are the little back wheels of the tricycle. These facet joints suffer damage with the reversed "S" shape curve that can occur in 100 milliseconds in rear-end crashes, and the supportive ligaments that surround the facet joints gets damaged with compression and then over stretching with hyper-flexion of the neck in the rebound phase. Damage to the facet joints and supportive capsular ligaments not only causes localized pain, sometimes described like a sharp stabbing pain, but also referred pain and spasms to corresponding areas, most notably the upper back and shoulder blade areas. Damage to the upper neck causes referred pain to the back of the head and radiating headaches to the forehead area.
Neurological symptoms classify the whiplash injury to at least a grade III injury, which can take over a year to heal, or damaged enough to where people suffer chronic pain and disability. Remember, these injuries can happen with little or no damage to either vehicle. Research by Panjabi, et al, at Yale University shows ligament, joint, and disc damage occurs in 6.5 - 8.5 "G" forces, and in research conducted at the Spine Research Institute of San Diego and elsewhere shows that a person's head can undergo over 10 "G" forces with only a change of velocity of 5 mph crash with little or no damage to either vehicle.
Some people have problems with their insurance company expecting all whiplash injuries to heal in 6-12 weeks. This is the length of time it takes for simple muscle strain injuries to heal, or grade 1 injuries. Statistically, only about half the people who suffer injuries in car crashes recover, the other half suffers chronic pain and disability. These are typically grade III-V injuries. I recently had a patient with a grade III whiplash injury with damage to her facet joints with referred neurological symptoms to her upper back and head. The insurance company wanted me to explain why her injuries are taking longer than 12 weeks. I replied by showing the guidelines describing grade III injuries and how it can take up to a year to heal. Many whiplash injury people have come across problems with their insurance company holding all whiplash injuries to grade I standards that all heal within 3 months. This policy, called the MIST policy (minor impact, soft tissue) was implemented by insurers in the early 1990's and still used today, despite the vast amount of whiplash related research done after this time dispelling the MIST policy myth.
Research based diagnosis and treatment is our motto, and if you or someone you know are suffering car crash injuries, we can help!