Send letter to journal:
Re: One size does not fit all

Sir

I welcome the caution shown by Amick (1) in his editorial on forearm support and mouse design for computer users. He praises the study design used by Conlon et al (2), but is a randomised control trial really the best way to assess ergonomic aids when there are so many confounders? Simple observation of a group of computer users will identify a range of postures, as well as a wide variation in arm length, wrist diameter, hand size etc. etc.. I have seen individuals who have undoubtedly benefitted from ergonomic adjustments to workstations, however the adjustments have been different in each case. I have seen similar numbers of individuals harmed by ‘ergonomic supports’ who responded rapidly once the desk was cleared of squidgy pads.

Consider another aid; we know that safety boots have a key part to play in reducing injuries, but we do not advocate issuing size 12 boots of one design to all. Not only should we ensure the boot fits, but some individuals will just not suit some designs. A randomised control trial of size 12 boots in a normal workforce may well show that safety boots cause slips, trips and falls and foot pain (because they don’t fit) rather than save feet (because they have a steel toe-cap). The same will inevitably apply to pointing devices and keyboards combined with desk size and height, chair design and position of equipment; some individuals will just happen to be ill-suited to the one design bulk-purchased for the department, while many individuals will be fine with the £25 chair and £5 keyboard and mouse from the discount catalogue.

Similar problems seem to arise with ergonomic assessments such as those undertaken by Access to Work and others. I have seen too many reports recommending the same standard ‘ergonomic aids’ for widely differing conditions (such as pneumatically adjustable chairs for visual difficulties and wrist extensor tendinitis) to have much faith in any ergonomic assessment that is based on ‘standard evidence’.

Evidence clearly shows that some individuals get problems, others don’t. Rather than trying to identify a single solution, should we focus more on analysing the problem, considering the ‘causal pathway’ as Amick suggests, but for individuals not populations? Then we can consider the best individual solution. This means that the issue is not one that should be based on research evidence, but on the observations of the occupational physician or nurse on the ground, on clinical assessment and clinical judgement. This may be a case where ‘more research is not needed’ unless it is much more clearly focussed; it may just muddy the waters. Instead we should have two messages:

1. If it ain’t broke, don’t fix it.

2. Assess and intervene early with a tailored solution when problems do arise.

Tony Williams

(1) Amick BC. Growing knowledge about ‘what works’ to prevent work injuries. Occupational and Environmental Medicine 2008;65:297-8 (2) Conlon C et al. A randomised controlled trial evaluating an alternative mouse and forearm support on upper extremity body discomfort and musculoskeletal disorders among engineers. Occupational and Environmental Medicine 2008;65:311-18.