Let’s think about Human Factors – a very important topic in Medical Devices.
Habits
I drink a lot of tea* as I work in the mornings. Each day, I fill the pot in the kitchen and carry it into the office. This morning, I realised for the first time that it hurts, every single day. Why does it hurt? How can carrying a kitchen utensil be painful? I had to (briefly) investigate. It didn’t take long to work it out. Let me explain because, significantly, I’d guess most people won’t understand the problem without pictures, while a few may find the whole thing completely unsurprising and painfully familiar.
If I pick up the pot sitting at my desk, I grab the handle as the designer intended, using all four fingers to create a tight fist around it and my thumb squeezing down on the horizontal bit on top. This isn’t your entry-level transport café teapot, so the handle is even nicely profiled to fit into my fist. I get a firm grip, strong enough to comfortably hold up 1.5 kg of tea and pot.
However, when I pick the pot up in the kitchen, I naturally put only three fingers through the handle. My little finger** goes outside it and I use the back of my finger to apply considerable force to stop the weight of the pot tipping it forward and pouring tea all over my socks.
I can’t adjust my grip in transit because the pot is full of not-quite boiling*** water and too hot to touch with my other hand (even if that wasn’t holding my mug). I just have to carry it all the way like that. And I’ve been doing this every day, for years, without thinking about it.
I’m a little teapot user, tall and (yes) stout
A little fiddling around and the cause is obvious: I'm slightly too tall for my kitchen. Picking the pot up from an elbow-height surface naturally gives the comfortable form of grip, but for me the kitchen worktop is well below elbow height and my forearm has to be angled downwards (unless I squat inelegantly). This makes the natural grip a weird, loose mess which requires my little finger to balance the weight and keep the pot level. And now I’ve noticed this, I realise I also do it with mugs, jugs, milk bottles and so on.
So whose fault is it? As a teapot manufacturer, you could argue that there’s nothing wrong with your teapot. It works perfectly for the average person using average-height worktops. But not many people are actually perfectly average and the square, vertical handle on my nice teapot is, now I look at it, very unforgiving of deviation from the imagined norm. I can’t easily change my kitchen or myself. The only thing that is easily variable here is the pot and perhaps, knowing all this, I’d choose a different design next time. I’d shop elsewhere because your product doesn’t suit my perfectly sensible circumstances. Your totally sane handle just lost you a sale.
Ergonomics and medical devices
Now, imagine if your flagship medical product was like this. You’ve designed a handle which everyone in the office says is comfortable, but the circumstances of real-world use lead some people to grasp it in a way that causes temporary pain and, potentially, lasting discomfort after many uses per day. Your device may perform its function successfully but people will still stop using it pretty quickly if it hurts them (and especially if that injury hampers them in using it).
If they stop using it, they’ll stop buying it.
If they stop buying it, you have no income.
If you have no income, you have no business.
When it comes to Human Factors, people like me harp on constantly about the Usability Engineering bit, because regulators demand it if you want to sell your product. However, it is equally important to remember Ergonomics, which is vital to continuing sales.
* Earl Grey even before lunch, because I'm a free thinker who lives by my own rules
** My pinkie, which I raise when drinking my tea because we can’t break ALL the rules – life would just be pure chaos
*** I’m assured making tea with actually boiling water is some sort of crime