Over five thousand American workers were killed on the job in 2016.1 Over the same period, almost three million nonfatal workplace injuries and illnesses were reported in the private sector.2 Every day, workplace incidents result in traumatic injuries such as fractures, amputations, sprains, tears, lacerations, punctures, contusions, and brain injuries.
Biomechanical analysis of injury causation can help resolve disputes regarding workplace incidents related to premises safety, equipment safety, and biomechanical hazards. A knowledgeable biomechanical expert can draw upon principles of physics and engineering to shed light on whether the loading necessary to cause a diagnosed injury was present in a claimed event.
In this article, Dr. Carolyne Albert provides a brief overview of biomechanical investigations involving three common types of workplace injury-causing events: falls, overloading, and contact with objects and equipment.
Biomechanics in Workplace Injury Litigation - Expert Article
More than 800 fatal and 200 thousand non-fatal work-related injuries were attributed to falls in the U.S. in 2016.3 Falls can occur from a height or from level ground. Falls from level ground are often the result of a slippery, uneven, or obstructed ground surface. Falls from a height, on the other hand, frequently involve unsecured openings in floors and walls, unprotected or improperly protected edges, unsafely positioned ladders, or misused safety equipment.
Falls occur when the body’s center of mass moves outside of the base of support. This loss of balance can occur for various reasons, for example:
- Slipping: Decreased friction between one’s feet and the ground, e.g., due to wet or icy conditions, can cause the feet to slide out from underneath the body’s center of mass, resulting in a fall.
- Tripping: While walking, an unanticipated toe impact against an uneven ground surface or obstacle stops the swinging foot while the body’s center of mass continues to move forward, causing a fall.
- Improperly protected edge: A balustrade or railing yields while a person is leaning against it, causing the body’s center of mass to move outside its base of support and resulting in a fall to the ground below.
Fall injuries are affected by several factors, such as:
- Fall distance: A falling body’s kinetic energy at impact increases with fall height. Consequently, higher distance falls tend to result in more severe injuries, given the same landing conditions.
- Position of the body at landing: At impact, the first part of the body to contact the ground comes to a sudden stop while the rest of the body continues to fall. Injuries can occur due to direct loading at the impact site, and/or away from the impact site due differential motion between regions of the body.
- Nature of the impact surface: During impact, the peak force between the body and the impact surface is inversely proportional to the stopping distance. All other factors being equal, impact with a soft, deformable surface like snow results in a lower peak force than impacting a harder surface with little deformation such as concrete.
A biomechanical analysis can help determine the cause of a fall, and/or how injuries occurred during a fall sequence.
A construction worker falls from an elevated platform onto the concrete floor below and sustained facial fractures. The cause of his injury is in question: did his face impact the platform during his fall, or are his fractures the result of a direct impact between his face and the concrete floor?
In this case, our biomechanical expert was able to demonstrate that the injury-causing load for his diagnosed facial fractures was applied directly to the front of his face and oriented rearward, consistently with the angle at which his body impacted the concrete floor. Had his face impacted the platform during his fall, the impact force would have been oriented vertically and would not have resulted in his diagnosed fracture.
Tissue failure occurs when forces applied on a tissue exceed its tolerance. A biomechanical analysis would draw upon the principles of physics and engineering, and established medical and scientific literature to determine whether pathological loading was generated in the claimed event to cause the diagnosed injury.
A delivery driver claims to have injured his back while unloading containers from his truck. He claims that a coworker let go of his side of the container unexpectedly, resulting in a lumbar disc injury.
Our biomechanical engineer was asked to determine whether his diagnosed lower back injury was consistent with the event as he described. In this case, our expert determined that the event generated forward bending of his lower spine that was consistent with the mechanism of his disc injury, and that this load was of sufficient magnitude to have resulted in this injury.
Contact With Objects and Equipment
Workplace incidents involving contact with objects and equipment are responsible over 200 thousand injuries and several hundred deaths in the U.S. annually.4 This type of incident includes being struck by a vehicle or a falling/rolling/flying object, and being caught in or compressed by running equipment.
Biomechanical analysis can be applied to verify whether an impact or impingement event generated appropriate loading to cause a claimed injury; and/or to determine whether the use or misuse of protective equipment played a role in the cause of an injury.
A forklift driver was sitting in his forklift with his left foot hanging outside the operator’s compartment when another forklift backed into him, impinging his foot. He claims that this event resulted in a left ankle fracture and a meniscal tear that was later diagnosed in his left knee.
Based on his described position and the direction of impact, our biomechanical expert determined that his ankle fracture was consistent with the impact event, but that this event did not generate the type and direction of loading necessary to cause the meniscal tear in his knee.
BIOMECHANICAL ANALYSES OF INJURY CAUSATION
The biomechanical experts at Robson Forensic offer a scientific approach to injury causation analysis. Forensic biomechanical investigations can be applied to various scenarios where the cause of an injury is in dispute, such as motor vehicle crashes, sports and workplace events, and falls.
By combining principles of mechanical physics with an understanding of injury biomechanics, our experts can determine whether an injury is consistent with the physical evidence and descriptions of an event. Our experts can also help elucidate whether an injury resulted from a defective product or device, and whether it could have been prevented.
For more information submit an inquiry or contact the author of this article.
Mechanical Engineer & Biomechanics Expert
Dr. Carolyne Albert is a mechanical engineer with expertise in pediatric and adult orthopedic and musculoskeletal biomechanics, as well as materials engineering. Dr. Albert applies principles of biomechanics, dynamics, and mechanics of materials to investigate injury causation related to slips and trips, motor vehicle crashes, falls, sports, and workplace-related incidents.
- U.S. Department of Labor - Bureau of Labor Statistics. https://www.bls.gov/news.release/cfoi.nr0.htm (Accessed October 29, 2018)
- U.S. Department of Labor - Bureau of Labor Statistics. https://stats.bls.gov/news.release/archives/osh_11092017.pdf (Accessed October 29, 2018)
- U.S. Department of Labor - Bureau of Labor Statistics. https://www.bls.gov/iif/ (Accessed October 29, 2018)
- National Safety Council. https://www.nsc.org/work-safety/safety-topics/struck-by-objects (Accessed November 1, 2018)