Are you a beach person? Or do you prefer fresh powdery snow?
We’re beach people - but we don’t want to lose you snow lovers, so just replace ‘sand’ with ‘snow’ and this can work for us all!
Imagine, sitting down in the most gorgeous soft sand with your back resting on one of those perfectly shaped dunes.
You fall asleep. It’s a peaceful sleep, and you don’t move an inch (or a centimetre…stay with me). Once you wake from your slumber, with one swift movement you stand and admire the impression that your body left on that gorgeous heap of sand. This, my friends, is your sitting footprint.
In your peaceful slumber, you were probably well-supported by the posterior surface behind you (the sand dune) and the inferior surface under you (the gorgeous heap of sand). If you’re like either of us, you were probably sitting with a kyphotic spine (rounded back), and maybe the side of your head was resting on the dune behind you.
The first thing you probably did when you got up was to give yourself a massive, much needed stretch. Your elbows probably went back, and your head probably tilted away from the side it was resting when snoozing on the dune.
If this sounds like you, then your sitting footprint probably looked like someone took a scoop out of the dune where your back was resting, another scoop out of the sand where your bum was sitting, and maybe a divot out of the dune just lateral to the scoop, where you laid your head. There would likely even be a gap between the scoop in the sand and the scoop in the dune, where your lumbar spine (low back) wasn’t quite making contact. If your legs were out straight in front of you, you might be able to see where your thighs were, and more than likely you’d have another scoop underneath your heels.
Now, imagine how different this footprint might look if you had chosen to lay on your left side. With your legs crossed, right on top of left. Perhaps we’d have a lop-sided scoop, with less sand displaced under the right side of your trunk, and only half of your bum represented in the sand. You might not see where the heels were, but rather the lateral (side) ankle and knee of the left leg.
I’m going to ask you to imagine just one more scenario, and then I’ll get on with it. Promise.
Imagine that before plopping down on your plot of sand, you make a perfectly fitting grove for your body to lay into.
You dig out a bit here, build up a bit there, and end up with a custom-made sand seat, complete with lumbothoracic support in just the right place with just the right amount of extension, lateral support to hug the natural curves of your trunk, pelvis, and thighs, and inferior support to meet the contours of your legs from the top of your thighs to behind your knees and down to the backs of your ankles and heels.
This is most likely the most comfortable sand seat you have ever experienced.
It doesn’t even matter if it’s soft sand or firm sand - the fact that it was made to fit your body means that you are fully supported, pressure more evenly distributed, with nothing more to ask for other than an ice cold drink (or a hot chocolate, if you’re in the snow!).
When you stand from this seat, without disturbing even a grain of sand, you notice that it looks the exact same as when you first sat down. Perhaps, if it was soft sand, it looks a little more packed down now that you’ve spent all day on it. But it’s packed down pretty evenly. No scoops. No divots. Just smooth, perfectly shaped sand. And anyone passing by would be able to tell a thing or two about the body that that particular sand seat was meant for. The sitting footprint was pretty well perfect.
If you were to put a pressure mapping system underneath your bum and back in each of the above scenarios, what do you think you’d see when looking at contact area?
If someone were to run their hand between your body and the posterior surface, inferior surface, and, in the third scenario, lateral surface - what do you think they’d feel?
I think that’s enough imagining for today, yes? Time to get on with it, I suppose.
When we talk about the sitting footprint, we are referring to the areas of contact between body and seating system. This can be considered supplementary to pressure mapping, because we are checking for symmetrical and adequate loading throughout all appropriate surface areas.
We assess the persons footprint in sitting and supine during our comprehensive hands-on assessment. There’s even a spot for documentation on the assessment form we created (click here to access)!
With the individual sitting as they usually do in their usual wheelchair, we always assess the sitting footprint right after assessing their Life Box. We want to know what does the Sitting Footprint look like/feel like when this person is in their current seating system? Are there areas of increased pressure that may lead to skin breakdown or pain? Are there areas that are not being loaded, which may result in instability or increase the work of sitting? Are the loading areas symmetrical and optimal?
Using a slide glove makes it easier to check, for both the clinician and the client.
We start with the inferior contact areas.
This means we slide our hand between the person and their inferior support surfaces (this includes the seat cushion, foot supports and arm supports) and document how much load or contact is happening at specific anatomical areas, such as the undersurface of the trochanters, ischial tuberosities, proximal and distal thighs/femurs, and under the feet and arms.
From here we travel to the posterior contact areas.
Again, using the slide glove with the person sitting in their usual way, we slide our hand between the person and their back support and head support, if applicable, and document how much load or contact is happening from the sacrum to the head and from right to left scapula and posterior/lateral ribs.
Once we have checked the primary loading areas (inferior and posterior), we next move to lateral and anterior loading areas, checking for variations in contact between right and left sides from the feet to the head, as applicable.
It’s important to note that the sitting footprint can potentially provide crucial information in relation to the presence, either current or future, of pressure injuries. We have been in situations where we have felt an area of extreme pressures (often under the ischial tuberosities or greater trochanter) and, upon further investigation, have found that the cushion is no longer functional or appropriate. In some of these situations, clients and caregivers have been told that if there was not an immediate change in pressure distribution, there would almost definitely be skin breakdown. There was even one instance where we did not feel that it was safe for the client to return to his seating system, and had to find a new cushion on the spot! As unfortunate as it is, we have received numerous calls from clients after that kind of conversation, confirming that they did indeed have a new pressure injury in the predicted area as a consequence of having to wait for changes to their prescription that wasn’t possible in the moment. Most recently, this occurred to a 13 year old girl who had no previous history of skin breakdown but had been waiting upwards of 6 months for a new seating system!
This is important information to document, and to explain to other health care providers and carers, as well as to the individual who is being assessed.
After we’ve finished the sitting portion of our assessment, we compare - what is the footprint like in sitting compared to supine in the posterior pelvis, trunk and head areas?
We expect the loading areas to be different in supine due to the assistance of gravity, but how much difference is there?
For example - are both scapula loaded/making contact in supine, whereas perhaps only one was making contact in sitting?
Is the sacral/lumbar area making more or less contact in supine when compared to sitting?
What happens to the contact area beneath the lumbar, thoracic and scapular regions when we are examining the ranges of motion at the hip or the hamstrings relative to the seated position?
The insight gained from these checks should lead us to question what is it about the external forces introduced by the seating system or wheelchair configuration that has created the compensatory postures leading to a difference in the footprint.
And don’t forget about translating the findings!
When we think we have an optimal solution in regards to body structure and function, we want to re-check the sitting footprint to make sure it is still at it’s most optimal when taking any structural limitation into account. Usually more contact area (a greater footprint) translates to increased stability, enhanced pressure distribution and decreases the overall work of sitting. We use this concept for all assessments whether the person presents with what might be perceived as a small postural deviation right through to individuals with more complex body shape distortion who may be candidates for custom built seating solutions.
Individuals we work with, families, care teams - everyone can check the sitting footprint!
Demonstrating that optimising the sitting footprint can be achieved through respecting limitations in body structure prior to creating a seating solution can be very helpful for everyone to understand and feel during the entire assessment process.
It’s also a great check for individuals, families, and care teams to perform after each transfer to make sure the person using the seating system is positioned optimally or as intended, with equal pressure distribution throughout all surfaces and no peak pressure areas.
Many clinicians don’t have access to an interface pressure mapping system. Our sitting footprint assessment step is not intended to replace the use of pressure mapping in any way, instead it is a simple step that with a slide glove or even a plastic bag over ones hand we can quickly gather important information that without a process can easily be missed.
You can practice feeling your own sitting footprint right now, in the same way that we previously practiced finding the Life Box (if you’re sitting, that is!).
Or, if you have a family member or friend who wouldn’t mind you practicing on them, you can get a much better feel for it.
When sitting upright with both feet supported and your back against the back support, slide your hand under your bum and find your ischial tuberosities (one on each side - these are your pointy sit bones and should be easy to feel!). Next, move your hands a little bit out towards the edge of your hips and push up - you should be near your greater trochanters now (these are much harder to find! If you’re having trouble, try to extend your leg and rotate it externally and internally or move it up and down and move your fingers around until you feel the bone moving). Once you’ve found these, move your hands under your thighs and slide them down to the back of your knees, noting whether both sides feel equal and how easy it is to move your hands as you go down.
Now, try this with different sitting positions! Cross one leg over the other; slide your bum down the seat and slouch forwards; slide one leg back behind your seat and the other on a small step; or give yourself some pelvic obliquity or rotation - and do the same thing as above! It’s tough to assess your own feet and back support, but you’ll be able to feel huge differences under your seat!
Interested in more information? Check out this quick video on the Sitting Footprint!