Commentary

This case concerns an important boundary matter that sometimes arises for orthopaedic experts in relation to biomechanics and ergonomics. These are areas of expertise for which the orthopaedic surgeon’s ‘working knowledge’ may be sufficient, thereby avoiding the time and expense of instructing a further expert just as in cases where knowledge and experience of orthopaedics in general is sufficient and it is not necessary to instruct an orthopaedic sub-specialist.

Learning points

• In a case where biomechanical or ergonomic issues may arise, it is advisable to explain your knowledge of the subject or subjects.

• Indicate that you will, if you consider it advisable, recommend the instruction of a biomechanical expert or ergonomist and, if appropriate, defer to them.

• Be in a position to give evidence about possible causation in specific situations relevant to the instant case.

• Be in a position to provide references to studies showing a correlation between load and injury. 

The case

The pursuer’s case was that she suffered loss injury or damage as a result of the defender’s fault and negligence. She was employed as a production operative at Mathiesons Bakery in Larbert. To succeed, the pursuer was required to prove that she was engaged in a manual handling operation, that there was a foreseeable risk of injury, and that she was injured by the operation.

History

On 31 May 2020, the pursuer was primarily engaged in work on the production line. On that day, she was instructed to collect twelve trays of cream for use on the production line.  The trays were to be collected from a window next to the production line, which formed part of the sanitiser tunnel within the defender’s production plant.  Each tray contained a ten litre bag of cream.  Each tray was plastic and a little wider than the pursuer’s body. The pursuer picked up each tray at about hip or waist height and lifted it to almost level with her shoulders.  Her arms were slightly extended in front of her.  The trolley was to the pursuer’s left hand side at 90 degrees to the window from which she was collecting the trays. The purser lifted around eight or nine trays and stacked them in turn on a flat trolley.  The pursuer immediately felt pain in her back after lifting the ninth or tenth tray from the window. The pursuer continued to work and took all twelve trays to the production line.

The following day when the pursuer got up for work she was unable to get out of bed immediately and fell to the floor when she tried to do so. The pursuer was absent from work for three months and her symptoms resolved within six months.

Skilled evidence

Her skilled witness was a consultant orthopaedic surgeon. His evidence was that, if the court accepted the pursuer’s evidence of lifting trays approximately 10 kg in weight from waist height to shoulder height on a trolley to her left resulting in pain in her back, he considered that to be a mechanism that could cause the pursuer to suffer injury.

The skilled witness explained that in the course of studying for the FRCS examinations, there were a number of modules on basic sciences including biomechanics dealing with the operation of the spine, lower limbs, hands, knees and arms.  In his evidence in chief he agreed that there was a risk of injury if a female lifted a weight of 10 kg from a low height to shoulder height with her arms partly outstretched.  This was evident from basic mechanics and how a load is applied.  If a load is at close distance to the spine, if the arms are outstretched the load is further from the spine and the greater the loading on the spine as a result.  Risk of injury could be reduced by reducing the load, the height, or the distance away from the spine.  That would include not lifting as high or as heavy a load.

In cross-examination, the skilled witness said that the higher the load, the higher the relative chance of injury.  He was not immediately in a position to provide references to a study showing a correlation between load and back injury, but referred to health and safety regulations which were very clear about load and risk.

Submissions

So far as foreseeability was concerned, the defender submitted that the skilled witness did not give evidence about the threshold load for the risk of injury and did not give evidence about height and distance in relation to risk.  It was submitted that the court required to have evidence about what lesser load and/or height would have avoided injury.

Counsel for the defender submitted that biomechanics and ergonomics are both recognised bodies of knowledge and are separate from the core specialism of the pursuer’s skilled witness, a consultant orthopaedic surgeon, notwithstanding that in the course of studying for the FRCS examinations, there were a number of modules on basic sciences including biomechanics. It was submitted that the issue really was one for an ergonomist which the pursuer had attempted to introduce but with which she had decided not to proceed.

Decision

The sheriff, having regard to the skilled witness’s training in biomechanics, was satisfied that, in principle, and subject to the ground being laid in evidence, he was qualified to give evidence about risk of injury in carrying out lifting at least at the level of principle as to whether certain types of lifting activity carry foreseeable risk of injury. The problem, however, was that the sheriff was not satisfied on the evidence he heard that the skilled witness was in a position to give evidence about possible causation in specific situations.  For example, at what carried weight would the risk of injury in a particular lift be more than de minimis;  or again, how many repetitions of a particular lifting operation would give rise to a foreseeable risk of injury, and it was evidence at that level of detail which was wanted and required.  

The sheriff’s finding was that the pursuer did not suffer loss injury or damage as a result of the defender’s fault and negligence.