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Unwitnessed Falls: 4 Ways Biomechanical Reconstruction Can Support Your Case

Expert Institute Expert

Written by
— Updated on June 7, 2021

Unwitnessed Falls: 4 Ways Biomechanical Reconstruction Can Support Your Case

After a slip, trip, and fall event, it can be difficult for counsel to establish a fact pattern if there is no third-party witness or surveillance footage available. The matter may be even further complicated by the plaintiff’s inability to recall the event.

In the absence of eyewitnesses or recordings, reengineering the fall becomes imperative. But reconstructing the event to determine its causal relationship to the plaintiff’s injuries is a complex issue. Such an analysis requires experts with specialized knowledge, training, and expertise in the area of human biomechanics and injury causation.

Here, I’ll be discussing the ways that biomechanical engineering experts can strengthen slip, trip, and fall cases. This includes how biomechanical engineering experts are able to reconstruct an unwitnessed fall event to pinpoint injury causation. Plus, I’ll explain how experts can support your case through injury pattern identification, demonstrative evidence support, and rebuttal to an opposing expert’s report.

A Look at Slip, Trip, and Fall Cases

Slip, trip, and fall events are quite common in occupational, recreational, and residential settings. Slip and fall incidents result in over one million hospitalizations every year in the United States[1]. These events, in general, are the leading cause of non-fatal hospital emergency visits and represent over 21% of total visits to the emergency room. The elderly population is largely affected—slip, trip, and fall events are the second leading cause of injury-related death for individuals age 65–84.

How Biomechanical Engineers Can Help

Biomechanics is a subset of biomedical engineering, the study and application of “traditional” engineering disciplines (i.e., mechanical, chemical, electrical) to the human body. Therefore, a biomechanical engineer employs the fundamentals of mechanics and mechanical engineering to analyze and evaluate biological tissues and materials. Biomechanical engineers are crucial when the mechanism of an injury is unknown or in dispute.

The role of a biomechanical engineering expert is distinct from that of a medical physician. In the context of litigation, a physician can address the accuracy of a diagnosis and the appropriateness of prescribed treatments (i.e., standard of care). Biomechanical engineers, however, are concerned with how the diagnosed injury was caused. They will then determine if the mechanism of the injury is consistent with the manner of the incident.

Biomechanical engineering experts rely on a combination of established scientific principles to investigate slip, trip, and falls. Following the scientific method, they employ physics, mechanics, and knowledge of injury mechanisms to determine whether the event generated the forces necessary to cause the diagnosed injuries.

1) Reconstruct the Incident

Expert opinions based heavily on the alleged victim’s testimony can be unreliable. This is particularly true when there are no other eyewitnesses to corroborate their version of events. In such scenarios, a biomechanical engineering expert can establish relevant details about the physical space where the event occurred. This is especially important for unwitnessed slip, trip, and falls.

A biomechanical engineer will conduct an inspection to record physical measurements (i.e., the height of a riser where a trip occurred, the width of a walkway where a slip occurred). Additionally, a biomechanical engineering expert will determine the spatial relationship between the plaintiff and other physical landmarks at the scene. This allows the expert to see how the plaintiff’s body interacted within the physical space and with other objects.

Biomechanical reconstruction of an unwitnessed fall event requires defining the diagnosed injuries. But it also requires identifying the body kinetics (forces) and kinematics (motions) necessary to cause a particular injury or pattern of injuries. An expert may then take the known site geometry, human anthropometrics (body size and proportions), and scientifically supported principles of motion to paint a picture of how the fall event transpired. Further, an expert can provide biomechanical expert opinions on injury causation.

Case Study

A contractor fell off a staircase landing at a construction site in North Carolina. Without the aid of video footage or other eyewitnesses, the attorney needed an expert to determine if the plaintiff’s fall caused his permanent shoulder injuries. Using the detailed measurements provided by the plaintiff’s construction expert, I was able to reconstruct the unwitnessed fall incident. From here, I could determine, based on the fall distance and position of the plaintiff’s body with respect to the open landing, that the fall generated the types of forces consistent with the mechanism of the plaintiff’s shoulder injuries.

2) Evaluate Pattern of Injury

In some unwitnessed falls, the alleged victim has multiple injuries they claim were caused by the incident. In many cases, the pattern of those injuries can be used to elucidate their kinematics (motions). This may be used in concert with the known mechanisms of each injury to determine whether some, all, or none of those injuries are consistent with the injury as claimed. This is particularly helpful in instances when the plaintiff can no longer recollect the incident or is deceased.

Case Study

An elderly man was on his riding mower outside his home in North Carolina when a tire from a passing tractor-trailer broke off. The loose tire allegedly struck the man and ultimately led to his death. As the man was deceased and no other eyewitnesses were present at the time of the incident, a biomechanical expert was needed to determine whether the deceased’s injuries were consistent with being struck by a tire traveling at a high velocity. In analyzing the pattern of injuries through photographs and an autopsy report, I was able to determine that the tire did not strike him as claimed. Rather, his injury pattern was more consistent with him simply falling off the riding mower to the ground.

3) Assist with Demonstrative Aids

Determining causation is a key part of the value a biomechanical engineering expert can bring to your case. In addition, a biomechanics expert can consult in the preparation of demonstrative aids by third parties. Employing visual aids that reconstruct the unwitnessed fall incident can complement your expert’s testimony. Further, they can more effectively drive the point home to the jury at trial. It is important, however, to ensure that your demonstrative aids are scientifically accurate. The visual reconstruction must follow basic scientific laws and principles to withstand scrutiny in court, be allowed into evidence, and assist the trier of fact.

Case Study

A man in suburban Philadelphia was pushing his father in his wheelchair. They then unexpectedly encountered a single-step riser, causing them to fall. Only the man’s brother was present at the time of the incident. However, he did not witness the event as his back was to the man and their father. Additionally, the alleged victim and his father were unable to fully recall the incident.

I was retained to reconstruct the unwitnessed fall incident to determine if the plaintiff’s cervical vertebra fracture was consistent with the mechanics of the fall. In addition, I consulted a third-party company retained by the attorney to develop a biomechanically accurate 3D animation simulation of the incident. The attorney presented this as a demonstrative aid during the jury trial. The animation helped the jury visualize the incident by illustrating the complex body mechanics that occurred during the incident. It also pointed out how the mechanism of injury was present in this case.

4) Analyze Opposing Expert’s Injury Causation Opinions

When opposing counsel retains an expert to opine on injury causation, it’s often beneficial to retain a biomechanical engineering expert to review and analyze the opposing expert’s opinions. Counsel may challenge the opposing expert’s biomechanical opinions on a few grounds. These include:

  1. Reliance upon poor, unscientific principles and methodology
  2. Lack of qualifications to establish expertise
  3. Improper application of scientific principles to the facts of the subject incident

Case Study

In the previous case example, opposing counsel retained a human factors expert who ignored available testimony. This expert also improperly applied Newton’s laws of motion. Instead, the expert offered biomechanical opinions related to injury causation that were incorrect and misleading. I addressed these points in a letter supplementing my initial report and findings. Here, I highlighted where the opposing expert failed to conduct a proper biomechanical investigation of the unwitnessed fall event.

Final Thoughts

Biomechanical engineers bring crucial insights to personal injury cases with their specialized experience, training, and expertise. Unwitnessed slip, trip, and fall events best demonstrate this. Here, biomechanical engineering experts are uniquely qualified to determine whether the claimed injuries are causally related to the incident in question.

Biomechanical investigation allows experts to establish the incident’s essential mechanisms of injury. Along with the relevant details of the physical space, a biomechanical engineering expert can reconstruct the human kinematics (motions) of the fall event. They can then determine the causation details surrounding the diagnosed injury and offer incisive intelligence attorneys need in every type of personal injury litigation.


[1] National Floor Safety Institute. Slip & Fall Quick Facts. Retrieved from https://nfsi.org/nfsi-research/quick-facts/

Expert Witness Bio E-703400

biomedical engineering expertLocation: PA
B.S., Engineering Mechanics, Johns Hopkins University
Ph.D., Biomedical Engineering, Drexel University
Member, Biomedical Engineering Society
Member, Orthopaedic Research Society
Former, Fire Protection Engineer, Jensen Hughes
Former, Biomedical Engineer, Robson Forensic
Former, Visiting Assistant Professor, Mechanical Engineering, Villanova University
Former, Assistant Professor, Mechanical Engineering, Villanova University
Current, Biomedical Engineer, a consulting firm in PA
Current, Adjunct Professor, Biomedical Engineering, a well-known university in PA
Current, Adjunct Professor, Mechanical Engineering, a university in PA

This expert has extensive experience in the field of biomedical engineering. He received his B.S. in engineering mechanics from Johns Hopkins University and his Ph.D. in biomedical engineering from Drexel University, with a dissertation titled “Mechanical characterization of the human lumbar intervertebral disc under impact loading conditions”. He is a member of several societies, including the Biomedical Engineering Society and Orthopaedic Research Society. Formerly, he served as a fire protection engineer at Jensen Hughes and a biomedical engineer at Robson Forensic. He has also served as a visiting assistant professor and an assistant professor of mechanical engineering at Villanova University. Currently, he is a biomedical engineer at a consulting firm in Pennsylvania where he provides biomechanical analysis of injury causation, and expertise on orthopedic devices and implants, biomechanical testing, and biomaterials. He also serves as an adjunct professor of biomedical engineering at a well-known university in Pennsylvania and an adjunct professor in mechanical engineering at a second university.

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