Nonetheless, in many cases, injury causation is not as readily apparent. Often, purported injuries are of the “soft tissue” variety. This pertains to damage to muscles, tendons, and discs instead of the bony structures. Although any given soft tissue injury can have an acute, traumatic cause, such injuries typically result from chronic deterioration or repetitive use. They exist asymptomatically in the individual, waiting to be discovered when that individual becomes a patient following an accident.

Determining Core Competencies

Are physicians the most qualified scientific experts to render opinions concerning causation? Physicians are able to determine the nature and extent of an injury or a condition –namely, to assert a diagnosis — and consequently the medically indicated treatment to either cure or ameliorate the injury or condition. These doctors will also render a prognosis, which covers the projected course of plaintiff's health with or without treatment. However, the question of whether a particular accident caused a discrete bodily injury is not merely a subject of medical expertise. Rather, it must involve a thorough analysis of the following factors:

• The instrumentalities involved and the mechanism of the accident.
• The kinematics of the involved individuals, including the motion of those affected by the accident.
• The injury mechanisms created (or not created) by the accident as well as the nature and magnitude of forces generated.
• The tolerance of a particular body part to particular forces applied by a particular mechanism.

The study and analysis of physical objects in motion — the mass, forces and energies associated with objects in motion, and the physical laws governing objects in motion — are properly the subjects of physics and mechanical engineering. As indicated below, a detailed scientific analysis of a discrete physical event such as a traffic accident can suggest whether the mechanism of the accident and the associated forces could have produced a specific injury to an accident participant. The scientist qualified to perform the analysis in this instance is the biomechanical engineer. In the appropriate case, this expert may be able to scientifically demonstrate that the opinion of the plaintiff's medical expert concerning causation is not, in fact, “reasonably reliable” at all.

Utilizing Biomechanics

The scientific discipline of accident reconstruction primarily deals with analyzing all relevant data to determine the mechanisms involved in an accident. The related field of biomechanical analysis is considered a subset of accident reconstruction, as it uses many of the same principles and methodologies. However, the biomechanical engineer goes a step further: he or she determines and identifies the mechanisms involved in the accident in addition to the types and extent of the physical forces associated therein. This engineer is also qualified to determine whether the accident exposed the plaintiff to the specific mechanism and forces known to cause the specific injury claimed. In other words, the field of biomechanical engineering applies mechanical engineering principles to human anatomy and physiology.

Although not usually a medical doctor — and therefore unable to render an opinion as to a viable diagnosis or prognosis — the biomechanical engineer is an expert on human anatomy and physiology. He or she will have a firm grasp of how various body parts function and the types of stresses and forces that will cause them to fail, meaning to exceed their natural physiologic ranges of motion.

By reviewing the plaintiff's available medical records and reports, a biomechanical engineer can unearth the nature and extent of the claimed injuries. The reviewing engineer relies on the treating physicians to define and describe diagnoses. Once the nature of the claimed injuries is understood, the engineer can define the mechanisms by which such injuries are sustained. The expert will then scientifically “reconstruct” the accident using principles and methods commonly accepted by the pertinent scientific community. This analysis must be based not only on subjective accident descriptions (as contained in deposition transcripts, signed statements, and accident reports) but also — and most importantly — on objective evidence relevant to the accident. This evidence will include the makes and models of the vehicles involved, as well as the nature and extent of the vehicular damage. If extant, repair records and post-accident photographs will be reviewed.

Using information about the respective makes and models, the engineer will calculate each vehicle's weight, mass, and stiffness. The expert will consider the direction and speed of each automobile, determining whether one or more vehicle braked before impact. This data will assist the engineer in calculating the amount of time that elapsed prior to braking and the distance of the vehicle(s) from the place of contact when the braking occurred. The points of impact will be gauged, along with the extent of damage inflicted to each vehicle.

The biomechanical engineer can figure out what happened to the plaintiff seated inside a vehicle during the accident. Conclusions can be drawn based on assessing where the plaintiff sat and whether he or she wore a seat belt. The expert will also examine the movements of the plaintiff upon impact and decide whether contact was made with the interior of the vehicle. If contact was made, then the engineer will ascertain the affected body part(s) and the precise location of the portions of the vehicle's interior that were in contact.

Decoding Motion

Further, the change of speed of the vehicles upon impact should be evaluated. Within the accident reconstruction community, describing the severity of a vehicular crash translates to quantifying the change in velocity for a struck vehicle, represented as “delta-v.” When energy is transferred in a traffic accident, the vehicles will change speeds to reflect the gain or the loss of energy. Meanwhile, the occupants inside the vehicle will continue to move at their pre-impact speeds. Thus, a discrepancy is created between the velocities of the vehicles and the velocities of the occupants inside, which in turn causes relative movement of occupants within the vehicles.

A thorough analysis will reveal if the accident provided an injury-causing mechanism and will thus indicate if the injured body part(s) sustained a force or load substantial enough to cause tissue damage. Essentially, if the expert determines that the accident did not furnish the mechanism for a specific injury or the necessary force to cause it — or both — then we can ultimately conclude that the accident could simply have not inflicted that specific injury.

The body of knowledge related to the force that a “normal” human body can tolerate without damage is extensive. The engineer will consider the height and weight of the plaintiff at the time of the accident. If the plaintiff was in fact suffering from a pre-existing condition that was allegedly aggravated by the accident, then New York law obligates the plaintiff to plead such an aggravation and identify the nature and extent of the pre-existing condition prior to trial. If no such aggravation is pleaded, then it may be presumed that the lawsuit claims that the accident caused plaintiff's injuries. If the pre-existing condition can be identified, then the biomechanical expert can factor it in the analysis.

Consider the case where a plaintiff, despite having been restrained by a seat belt, claims to have sustained serious injuries in a low-speed motor vehicle accident. The courts are filled with litigated cases involving a variation of the following scenario: The plaintiff motorist or passenger alleges that an injury requiring surgery, such as a rotator cuff, meniscal, or knee ligament tear or perhaps spinal disc herniation with pain radiation, stems from a low-speed car crash with minor resultant property damage. The plaintiff's treating physician may deem the subject accident, which the plaintiff may verbally describe, to be the competent producing cause of the serious injury. The physician asserts this without reviewing any documentary material, such as accident reports prepared by investigating police officers or accident participants; the parties' deposition testimony; property damage photographs; or repair documents.

Confronted with evidence of the low-speed impact and minor collision damage, the jury may be skeptical that a minor accident actually caused such injuries. On the other hand, however, the plaintiff's doctor testifies to a causal connection — in other words, “proof” the minor accident caused the injury in question — based solely on the plaintiff's subjective description of the accident.

Of course it is also likely that the treating physician will not have reviewed pre-trial disclosure material about the accident. Such a review is not customarily part of the doctor's “job description,” as it falls outside the realm of diagnosis and treatment. Nonetheless, the plaintiff's medical expert has not reviewed critical material concerning the incident and its mechanics and is presumably not qualified as a physical engineer to analyze the motions and forces involved in the accident. Therefore, it can be argued that a doctor is not the most competent expert to express an opinion about causation.

Indeed, an argument can be made that, under the circumstances, the doctor's opinion lacks probative force where the conclusions are “speculative” or “merely possible.” At worst, the medical witness' unfamiliarity with the details of the accident and with scientific biomechanical principles used to analyze accidents may be fruitful areas of cross-examination pertaining to the weight of the evidence.

New York Courts have recognized the competency of biomechanical engineers to testify on causation issues. Particularly in cases where diagnostic films reveal chronic, pre-existing degenerative conditions affecting the supposedly injured body part(s), biomechanical expert testimony can provide persuasive scientific evidence to dispute the causal link between accident and injury. To add this powerful tool to the defense arsenal, lawyers must become conversant with biomechanical engineering principles and related trial techniques to maximize their effectiveness in court.

Richard M. Sands, Esq., is a senior litigation counsel member at Harvey Gladstein & Partners, LLC. He may be reached at 212-952-1111; [email protected]; www.gladsteinlaw.com.

Special thanks to Biomechanical Engineer Brian J. Benda, Ph.D. and Sean O'Loughlin, President, Global Biomechanical Solutions, Inc. for their assistance.