Injury Causation

Many types of incidents, including low-speed vehicle impacts, rapid elevator or escalator stops, and slips, trips and falls, result in injury claims that may or may not be attributable to the incident.  In order to determine whether a claimed injury occurred as a result of a specific incident, Exponent’s biomechanics staff analyzes the mechanism required to cause the injury traumatically and investigates whether that mechanism was present in the subject incident.

Common questions regarding injury causation can be answered through biomechanics:

  • How does the diagnosed pathology occur traumatically and under what loading conditions?
  • Was the necessary injury mechanism present in this accident?
  • Is the loading sufficient, relative to established tolerances, to produce significant potential for injury? 

Exponent’s Analytical Approach to Injury Claims 

To assess the loads acting on the body, one generally starts by analyzing the subject incident. For incidents involving motor vehicles, accident reconstruction is performed to determine the vehicle dynamics and the resulting kinematics. These, in turn, are used to assess the motions and loading experienced by the occupants.

Once the motions and loading associated with an incident are known, the effects on the human body can be evaluated. Exponent and others have performed numerous tests with instrumented anthropomorphic test devices (ATDs), also known as crash test dummies, which allow for the direct measurement of motions and loads and evaluation of these loads using established injury assessment reference values. Research studies, including many performed by Exponent, with human volunteers wearing instrumentation, have quantified body motion and loading under various activities. For other types of incidents, such as a trip and fall, slip and fall, or impact with an object, appropriate research and testing, either performed by Exponent or available in the literature, can be referenced to determine the loads acting on either the body as a whole or on a specific body region. Exponent’s biomechanical consultants also employ computer modeling studies and incident-specific simulations, when appropriate, to assess kinematics and response to applied loading.


Exponent’s capabilities include:

Head Injury

To assess whether a particular mechanical event could have resulted in Mild Traumatic Brain Injury (MBTI), our engineers evaluate the head accelerations produced in the event in relation to the risk and potential for MTBI. We also can provide perspective to head accelerations produced in a mechanical event, such as a low-speed motor vehicle collision, by comparison to head accelerations produced in everyday and simply physical activities.

Upper and Lower Back Injury

To determine whether a particular incident caused acute injury to ligaments, bone, or discs of the spine the biomechanical engineer first assesses the nature of loading to the spine. For instance, in claims regarding the vertebral disc, the biomechanical analysis focuses on the type of the loading generated in the incident and whether it presents a mechanism for traumatic disc injury.   If a disc loading mechanism exists, the magnitude of the load can be compared not only with established tolerance values for the general population, but also with the individual’s tolerance as demonstrated by his or her daily activities. Additionally, the biomechanical properties of the disc, the biomechanics of disc aging and degeneration, and the presence or absence of adjacent vertebral injuries can assist in the determination of whether a disc herniation was produced by an acute traumatic event.

Shoulder Injury

Shoulder injuries such as labral tears can occur traumatically when the humeral head compresses against and slides relative to the glenoid, shearing a portion of the labrum. Our staff can analyze the anatomy of the tear, determine the direction of force application required to cause a labral tear in a particular location, and evaluate whether a specific incident provided the requisite loading mechanism either directly to the shoulder or indirectly through the arm.

Lower Extremity Injury

As in other joints of the body, the bones and the soft tissues of the knee can fail acutely in trauma or can deteriorate over time with mechanical wear and tear and/or through degenerative pathologies. Traumatic injuries of the knee require force applications to load the tissue and generally reveal a pattern that indicates the combination and direction of the applied forces. In evaluating whether knee injury was caused by a particular event, the incident is first evaluated to determine whether direct knee contact or indirect loading of the joint occurred. Our staff then evaluates whether the direction and magnitude of the forces in the event are consistent with the anatomy of the specific pathology (e.g., is the direction of a contact force consistent with the location and direction of a meniscal tear?). Also, as in spine and shoulder pathologies, the presence or absence of associated knee injuries or degenerative pathologies can inform whether a claimed injury occurred as a result of acute traumatic loading or as a part of a degenerative process.

Using our extensive resources and expertise, Exponent can reconstruct and analyze the mechanical loading generated in a wide array of incidents, and then compare the magnitudes, directions and combinations of that loading with motions of the human body and mechanisms necessary to cause many types of injuries.



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