Last week a very important study was published for doctors and lawyers who handle traumatic neck injuries. The study, published in the International Journal of Environmental Research and Public Health, is the result of 10 years of work reviewing the validity of motion X-ray in the determination of causation in cervical spine injuries. This study promises to be a game changer in providing objective evidence of injury in patients with chronic pain after whiplash trauma.
The study describes an analysis of the motion x-ray (aka video fluoroscopy [VF] or dynamic motion X-ray [DMX]) studies of 196 people (77 normal, and 119 with chronic neck pain after a traffic crash). The purpose of the study was to see if the examination could discriminate between injured and uninjured subjects.
VF is used to examine how the vertebrae move, relative to each other, through the range of voluntary motion. A main abnormal finding of the study is intervertebral instability due to ligament injury, which is typically diagnosed when one vertebra slides too far relative to the one below it. The two examples below demonstrate the difference between normal (fig 3), and abnormal (fig 4) motion of C2 on C3 vertebra in flexion of the neck:
This study, designed and carried out by forensic epidemiologist Dr. Michael Freeman and his colleagues, took place over a period of 10 years and examined the diagnostic accuracy of VF for detecting injured patients. In other words, when the VF study is positive for presumptive injury, how often does this really mean that the person is injured? Or, is the finding one that is common in healthy and uninjured people? The term for this test metric is positive predictive value (PPV), which gives the percentage of certainty that a positive test means that the condition is present.
Radiologists who commonly testify for the defense uniformly dismiss findings of instability (typically diagnosed by more than 2 mm of abnormal sliding of one vertebra over the other), claiming that such findings are normal in the asymptomatic population “in their experience.” Of course, radiologists don't read X-rays or MRIs of the asymptomatic population, and defense radiologists certainly aren’t interviewing normal patients or even your client. Thus, their experience with such a population is essentially zero. Regardless, insurers largely consider radiologic findings of instability to be as subjective as pain complaints.
The findings in this new study utterly destroy this defense. Freeman and his team examined 37 different types and locations of spinal movement in the cervical spine and found that the average uninjured person had 1.2 abnormal findings, whereas the average injured person with chronic pain had 7 abnormal findings. Next they found that when a study had 2 or more abnormal findings, there was an 88 percent chance that the person the study was performed on was injured, and when there were 4 or more findings the probability the person was injured was 100 percent.
Compare these values to the preponderance of evidence standard and you will understand why the findings in this study are important for proving injury. Not only do they prove that injury is present and real, but they also demonstrate the nature of the pathology that resulted from the trauma of the crash, which is demonstrable injury to the stabilizing ligaments of the spine (primarily to the ligaments of the facet joint capsule).
While Freeman et al. studied VF of the spine to arrive at their conclusions, many of the same injury findings can also be detected using plain X-ray with flexion-extension views, and lateral flexion X-rays with the mouth open (to see the upper cervical vertebrae without the teeth blocking the view). These are the kinds of views that a lot of doctors routinely take for cervical trauma patients.
The defense cannot simply dismiss positive findings of instability as evidence of injury anymore; this study is the best science on this topic that exists.
This study was published in a well-ranked international journal, which has an open access policy. We are posting the article here for your use in present and future cases.