By: Michael Prange and Ray Daniel, Exponent Inc.
Concussions and the role of a biomechanical engineer
In the past decade, there has been a general increase in awareness and emphasis on concussions. Overall, the diagnosis of concussions has increased over the years but it is unclear if this is due to an actual increase in incidences or a result of the increase in awareness and the evolution to the definition of concussion. In the past, loss of consciousness or amnesia was considered a necessary symptom. However, the American Association of Neurological Surgeons currently defines a concussion as a “clinical syndrome characterized by immediate and transient alteration in brain function, resulting from mechanical force or trauma.” Objective clinical evidence of concussions can be difficult to obtain as there currently are limited empirical tests for this type of injury such as blood tests or radiological studies. As such, medical doctors sometimes diagnose this injury based on the patient’s description of symptoms and their history of an event. Some instances of concussion can be straightforward such as a loss of consciousness after a severe blow to the head. However, not all instances of concussion are so obvious. Many times, the specifics of the incident such as the number of impacts sustained, direction, or severity of a specific impact are impossible for a medical doctor to quantify. In these situations, a biomechanical engineer can help understand the severity of the incident and the associated risk of concussion.
Although biomechanical engineers can assist in understanding the associated risk of concussion during specific events, it is often the job of a medical doctor to correctly identify that the injury sustained was in fact a concussion. The Kentucky’s Medical Practice Act defines the practice of medicine or osteopathy as the “diagnosis, treatment, or correction of any and all human conditions, ailments, diseases, injuries, or infirmities by any and all means, methods, devices, or instrumentalities.” In other words a medical doctor is a professional who diagnoses and treats a variety of conditions. In contrast, biomechanical engineers examine the relationships between the forces applied to the human body, the motions of the human body, and the physical mechanical damage to structures of the body. A biomechanical engineer evaluates the incident to determine the forces and motions on an individual’s body and if the tissues of the body have reached their biomechanical limit. A medical doctor determines exactly the pathology created and/or the medical reason for the symptoms (diagnosis) then addresses these through medical interventions (treatment). Biomedical engineers are specifically trained to understand the circumstances that lead to a traumatic injury while the medical doctor’s role typically starts after the injury has occurred. The human body, like any other structure, has material properties that affect its behavior when exposed to mechanical loading. A biomechanical engineer can evaluate the forces and motions generated in a specific situation and compare those mechanics to data of the tolerance of the biological structures involved. This analysis differs from that of a medical doctor as a physician’s analysis is focused on diagnosing and treating injuries and medical conditions.
In regards to concussions, biomechanical engineers have a number of tools to evaluate the mechanism of this injury. These tools include numerous peer-reviewed research studies conducted using various techniques such as field incident data, human surrogates, anthropomorphic test devices (ATDs or crash test dummies), and biomechanical models. This research has resulted in the development of correlations between head motion (kinematics) and the risk of brain injury. Biomechanical engineers then can determine the head motions during a subject event based on the laws of physics and