Keoghs Insight

Author

Clare Kenny

Straw that broke the camel’s back lifted

AWARE18/02/2014
Disease Aware Issue 4

Claims for the acceleration of degenerative conditions have been an issue for Employers’ Liability Insurers for a number of years. Claimants and their experts argue that repetitive strain injuries of the back have accelerated the onset or progression of degenerative back conditions. This article considers some of the most significant medical studies of the last twenty years to examine the relationship between repetitive strain injuries of the back and disc degeneration. Is there a relationship between the two? Can the former actually cause the latter?

Summary of twin studies

For years there has been debate about what the primary causes of disc degeneration are. Opinion has changed considerably over the past decade. Traditionally, disc degeneration has been associated with factors such as age, gender, trauma, exposure to whole body vibration, occupational physical loading, smoking and obesity.

In a 2012 study by Eskola and others, it was suggested that disc degeneration is principally due to genetic predisposition and that environmental factors play a much smaller role than was previously believed.

An earlier study by Hancock and others is perhaps the article of most interest to defendant litigators. The study compared the level of disc degeneration in 38 pairs of identical male twins, one of whom had experienced a previous back injury, and one who had not. Of those who reported previous back injuries, 25 had experienced one back injury and 13 had experienced two. A previous back injury was deemed to be, “a specific significant incident or accident involving excessive loading or trauma likely to result in tissue damage.”

Disc degeneration was measured using MRI scans. The study showed that the number of injuries was not associated with differences in disc degeneration between the twins. The study concluded that a history of back injury was neither a risk factor for accelerated disc degeneration, nor an important predictor of future disc degeneration.

In 1996 Savage and others considered whether there were differences in the MRI appearance of the lumbar spine between various occupational groups. They found no differences in the lumbar spine between the five groups studied: car production workers, ambulance men, office staff, hospital porters and brewery draymen. The authors said that it is generally agreed that heavier work is more likely to cause back pain in an individual. However, the study suggested that despite the mechanical stresses applied to the lumbar spine, disc degeneration was no more prevalent in men employed in manual occupations than in men with sedentary occupations.

The article refers to a further study carried out by Altman in 1991 which found that the effects of physical loading factors on disc degeneration were small, and were dwarfed by those of familial aggregations which reflected primarily genetic and shared early environmental factors. The view that disc degeneration is primarily caused by inherent factors is given further support in studies by Videman in 2006 and Battie and Videman in 2008. The former even suggested that repetitive loading might have a beneficial effect, delaying disc degeneration.

Use of the studies in litigation

Keoghs have successfully deployed these studies to repudiate claims for disc degeneration or acceleration. In one instance, the claimant worked as a drayman. His job required him to handle heavy barrels, delivering to public houses across the North West. A typical day for the claimant would involve delivering 70-80 barrels. The claimant argued that his 17 years in this occupation had led to acceleration of degeneration in his lumbar spine.

It was not in issue that the claimant had a degenerative lumbar spine. His medical records showed a long history of complaints of back pain. His medical expert asserted that his work had caused the degeneration to progress at a much greater rate - such that he was experiencing symptoms of significant severity some five to seven years earlier than he would ordinarily have done.

There were no real arguments on breach of the manual handling guidelines. The issues were limited to medical causation. The defendant instructed Mr Neil Oxborrow and relied on the recent studies. His unequivocal view was that although the claimant’s heavy manual occupation may have caused transient symptoms, medical literature simply did not support the assertion that it had caused any acceleration of the degenerative process. The claimant’s medical expert abandoned his view of causation and conceded that there was little evidence to support an acceleration.

Conclusion

Opinion as to the causes of disc degeneration is changing. Far greater emphasis is now placed on genetic factors. Far less weight is now given to occupational causes.

Insurers should now treat with scepticism any suggestion that repetitive lifting can cause an acceleration. The claimant must demonstrate that the symptoms he complains of are not constitutional. He must demonstrate the nature and extent of any alleged increase of symptoms, over and above that ordinarily experienced by him. Any work related injury would ordinarily be a transient soft-tissue injury and not one with long term effects.

Insurers would also have to be wary of another argument supported in the 2008 case of Goodwin v Bennetts, CA. Although the underlying causes of a condition might be constitutional, a defendant might still be liable for symptoms (i.e. the immediate pain) caused by specific and identifiable breaches of duty. In either case, damages would be minimal compared to the years worth of ‘acceleration’.