Medicolegal causation analysis of a lumbar spine fracture following a low speed rear impact traffic crash

Epidemiologic study indicates that low speed traffic crashes are associated with a relatively low risk of significant injury. This fact is often used to defend legal actions in cases in which it is alleged that a significant injury has resulted from a low speed crash. Injury causation following a low speed collision can only be assessed by comparing the risk of injury from the crash to the risk of the injury occurring at the same point in time, but absent the exposure to the crash. As a practical matter in a clinical setting, this means that a history of close temporal proximity between the collision and the onset of symptoms is the strongest indication of causality, irrespective of a low injury risk associated with the collision. In the present case study an acute superior endplate fracture and bilateral facet fracture was observed in the lower lumbar spine in a 49 year old female occupant of a vehicle that was struck from behind at low speed. Injuries to the patient’s neck and shoulder were ultimately diagnosed as intervertebral disk derangements and glenoid labrum tear, respectively. As a result of the injuries the patient underwent four spine surgeries and an arthroscopic procedure on her shoulder. Various experts for the insurer asserted that the injuries and subsequent need for treatment were unrelated to the collision, in part based on the low risk of such injuries from a low speed crash. The methodologic and logical errors committed by the insurer’s experts in arriving at these conclusions are discussed.