CTP Insurance, Insurance

The Persuasion of Biomechanical Evidence in the Causation Equation

2 April, 2024

In Brief

  • When assessing whole person impairment, the onus is on the claimant to demonstrate that their injury was caused by the subject motor accident.
  • Expert bio-mechanical evidence may be relevant to the question of whether the forces involved in the accident were capable of causing the injury alleged.


On 28 March 2024, the Personal Injury Commission published its decision in Transport Accident Commission of Victoria v Kelyana [2024] NSWPICMP 148.

The claimant was driving a bus when the Insured inadvertently sideswiped the right rear corner of the bus.

A PIC medical assessor found that the motor accident caused a disc prolapse at C3/C4 with left C4 nerve impingement. The medical assessor found 13% WPI, including impairment of both shoulders based on the Nguyen principle.

The Insurer argued that the motor accident did not cause any injury to the claimant’s cervical spine. It successfully sought review of the medical assessor’s WPI determination.

The Medical Review Panel’s Reasons

The Medical Review Panel determined that the motor accident did not cause any injury to the claimant’s cervical spine for the following reasons:

  • The biomechanical evidence established that the insured vehicle was travelling at a speed much less than 10 kph.
  • The change in velocity of the stationary bus was 0.6 kph at the time of impact.
  • A biomechanical expert qualified by each party agreed that the dynamic forces operating on the bus were well below the injury threshold for harmless impacts.
  • The impact impulse involved in the collision provided less movement to either the claimant or his passengers than 80 observable occasions prior to the collision where the bus travelled over expansion joints in the roadway and speed humps.
  • If the claimant was predisposed to injury, then he would have been injured by one of those 80 incidents rather than the trivial impact forces caused by the insured vehicle.
  • If the accident caused a disc lesion, as alleged, the claimant would have noticed it immediately and it would have been difficult for him to stand up and exit the bus, as he did.
  • Ultimately, the nature of the impact was so small that it could not have aggravated the claimant’s pre-existing condition or created a new condition.

Key Learnings

The decision in TAC v Kelyana provides a reminder that expert biomechanical opinion may be persuasive on the issue of causation. In the individual circumstances of this claim, it was telling that the Insurer’s expert viewed the CCTV for a period prior to the accident and observed 80 events which involved greater impact impulse than that involved in the motor accident alleged to have caused the Claimant’s injury.

If you have a query relating to any of the information in this case note, or would like to discuss a similar matter of your own, please don’t hesitate to get in touch with CTP Insurance Principal, Peter Hunttoday.

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