Traumatic Spinal Cord Injuries (SCIs) Expert Article

Traumatic spinal cord injuries (SCIs) are commonly associated with loss of body functions that adversely impacts autonomy, social life, and finances, and can incur lifetime costs often reaching millions of dollars. SCIs often result from traumatic incidents, such as motor vehicle collisions, falls, industrial accidents, sport incidents, and assaults, that may be the subject of litigation.

When the circumstance under which a traumatic SCI occurred is disputed, a biomechanical investigation can help the trier of fact understand the mechanics of the incident that caused the diagnosed injury. This article discusses the biomechanics of traumatic SCIs in the context of legal disputes.

Biomechanics of Traumatic Spinal Cord Injuries (SCIs)

Biomechanics is the science that deals with the responses of the body to internal and external forces (loading). A qualified biomechanical engineer can apply fundamental principles of physics and engineering to the evidence of a case to investigate the forces and/or body motions that caused a diagnosed injury, such as an SCI.

Spine Anatomy and Physiology

Traumatic SCIs result from forces that deform the spine and damage the spinal cord. Knowledge of spine anatomy is essential to understanding the biomechanics of traumatic SCIs.

The human spine (Figure 1) is comprised of seven cervical vertebrae in the neck, twelve thoracic vertebrae in the upper and mid back, five lumbar vertebrae in the lower back, and five sacral vertebrae and the coccyx below the lumbar spine. The vertebral canal is a bony channel at the center of the spine that contains and protects the spinal cord.

The spinal cord is a bundle of nerve tissue, approximately one and a half feet long in adults, that conducts signals between the brain and the rest of the body. These nerve signals transmit sensory information (e.g., touch, positions of joints, hunger, and pain) from the body to the brain, as well as motor instructions from the brain to the body to accomplish motions and bodily functions.

An SCI can disrupt these signals and result in impaired sensation, movement, heart rate regulation, breathing, digestion, urination, and other functions.

SCIs can affect one side of the body (hemiplegia) or both, and can be complete, with total loss of motor and sensory signals below the injury level, or incomplete, where some signals can still pass through the damaged spinal cord tissue. 

The American Spinal Injury Association (ASIA) provides a standardized scale, the ASIA Impairment Scale (AIS), to describe the impairment severity in SCI patients, with five levels ranging from Grade A (complete impairment) to Grade E (unhindered functions).

An SCI can occur at any spinal level, and the location of the injury plays an important role in the resulting impairments. Generally, the higher the spinal level of injury, the more functions are affected. For example, lumbar SCIs commonly result in impaired lower body function (paraplegia), whereas cervical SCIs can affect all limbs and the torso (quadriplegia) and may affect breathing.

Biomechanics of SCIs

Traumatic SCIs result from the spinal cord being deformed by surrounding spine tissues, most commonly due to spinal injuries such as vertebral fractures, dislocations, and/or intervertebral disc injuries. Each type of spinal injury is associated with its own biomechanical mechanism of injury, such as excessive extension, flexion, lateral bending, axial rotation, axial compression, tension, shear, or combinations of these types of loading (Figure 2).

A qualified biomechanical expert can provide answers to questions such as:

• What type and direction of force were necessary to cause the diagnosed SCI?
• Is the loading necessary to cause the diagnosed SCI consistent with the incident as the plaintiff testified?
• What fall mechanics resulted in the traumatic SCI?
• In a multi-impact motor vehicle collision, which impact generated the force necessary to cause a diagnosed SCI?

Sample Case

A construction worker was found unconscious next to a ladder at a job site. His diagnosed injuries included a cervical spine fracture at C6-C7, with an associated incomplete AIS Grade C (incomplete) SCI. The worker had no recollection of the incident and there were no witnesses. Our expert was asked to investigate whether his injuries are consistent with a fall from the ladder or from ground level.

In this case, our expert determined that the worker’s specific diagnosed injury pattern resulted from axial compression and flexion (forward bending) of the cervical spine, and that this mechanism was generated by a backward fall from an above-ground position onto the back of his head. Based on the results of this biomechanical investigation, our expert concluded that the worker had fallen from the ladder.

Biomechanical Engineering Investigations

The biomechanical experts at Robson Forensic offer a scientific resolution to conflicting testimony. By applying injury biomechanics and the principles of physics and engineering, it is possible to determine if an injury is consistent with the physical evidence and descriptions of an event.

For more information, submit an inquiry or call us at 800.813.6736.

Featured Expert

Carolyne I. Albert, Ph.D.

Mechanical Engineer & Biomechanics Expert

Dr. Albert is an expert in mechanical engineering with specific expertise in orthopaedic biomechanics. She applies principles of biomechanics, dynamics, and mechanics of materials to determine the… read more.