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What Causes Posterior Tilt & How Can Specialist Seating Help?

Maintaining good posture whilst sitting is key. Poor posture is associated with all sorts of health problems, from general aches and pains to significant bladder and breathing problems. For people with postural abnormalities, like posterior tilt, it’s not always easy to achieve proper positioning in a chair. So, what can be done to avoid any negative outcomes?

Specialist seating can help to support any postural abnormalities. The right chair will provide comfort and prevent the problem from getting worse. In some cases, seating can even correct postural abnormalities!

In this guide, we’ll look at posterior tilt, its possible causes, and how specialist seating can help.

Jump straight to…


What is ‘normal’ posture?

Before we get into the details of posterior tilt, it’s important to understand what normal posture looks like.

We’ve written about improving posture a lot over the years. So, we acknowledge that good posture can look different for different people.

However, for a healthy person with no spinal or pelvic issues, their neutral posture should look something like this:

Normal posture when sitting should have a slight natural curve in the spine

The scientific explanation


To assess posture, look at someone’s head, spine, and pelvis positioning.

Someone sat with normal posture will have…

  • Their head functionally upright and aligned over the hips.
  • Their spine in an upright position, with no lateral curve just the natural “S” shape curve from the lumbar spine to thoracic spine.
  • pelvis in a midline position with the:
  • Anterior Superior Iliac Spine (ASIS) & Posterior Superior Iliac Spine (PSIS) at equal heights.
  • Left ASIS & Right ASIS at equal height and depth.

Labelled diagram of the human pelvis

Now we know what ‘normal’ posture looks like, let’s look at how posture differs in someone with posterior tilt.

What is posterior tilt?

Posterior tilt is a postural abnormality that occurs when the pelvis tilts backwards.

Healthcare professionals sometimes call it “sacral sitting”.

Where is the sacrum? Labelled lower back diagram

That’s because people with posterior tilt end up sitting with their weight going through their lower back (sacrum) rather than their bottom.

DIAGNOSIS TIP: You may notice someone with posterior tilt has a C-shaped spine with rounded shoulders and their eyes looking downwards.

The scientific explanation

Posterior tilt is all about the pelvis. In medical terms, it means the PSIS is lower than the ASIS.

Posterior Tilt when sitting

This is how someone’s spine and pelvis looks when sitting with posterior tilt

Possible causes

Obesity is a risk factor for posterior tilt, and lack of muscle tone is another common cause.

Critically, a poorly fitted chair can also cause posterior tilt! So, getting seating right can stop this abnormality developing in the first place as well as helping correct it.

There are many other risk factors for posterior tilt – Download our free Specialist Seating eBook for more details on causes.

Can specialist seating correct posterior tilt?

In short, it depends.

If someone’s posture is still flexible, then it may be possible to correct the pelvic tilt. However, if their posture is fixed, then unfortunately the abnormality is permanent.

Definition Goal with seating
Flexible posture The spine and pelvis still move –        Prevent posture becoming fixed in posterior tilt.

–        Correct positioning back towards normal posture.

Fixed posture The spine and/or pelvis will not move from their abnormal position –        Accommodate the fixed posterior tilt posture.

–        Prevent further progression — posterior tilt can develop into more severe kyphosis if left untreated.


Chairs for people with posterior tilt

When choosing a chair for someone with posterior tilt, there are three main areas to consider — sizing, back angle, and footrests.

1)     Adjustable seat sizing

Seat sizing is key for people with posterior tilt. Seat height, seat depth, and arm height are the most important measurements:

  • If the seat depth is too high or too low, the user can slide forward.
  • If the seat is too high, the user may slouch so they can rest their feet comfortably on the floor. The result is the same as with seat depth.
  • If the armrests are too low, again the user can end up slouching to get comfortable.

Seat height, seat depth & armrest height are crucial in seating for someone with posterior tilt. Our free seat sizing form can help you take accurate measurements

Whatever the sizing issues, the result is the same. Over time, this pressure builds up on the sacrum and causes the pelvis to tilt backwards, causing posterior tilt.

You need a bespoke chair that is made-to-measure or one with adjustable sizing that can be perfectly fitted to the user.

We recommend adjustable sizing where possible. It means you can adjust the chair as needed when someone makes progress with their posture!

The Lento Care Chair has fully adjustable seat sizing

2)     Adjustable back angle

If the backrest is too upright, it can impact hip flexion and cause/exacerbate posterior tilt.

Hip flexors are the muscles that allow you to bend you leg up towards your torso — as you do when you’re sitting. This movement is called flexion.

When someone is sitting for long periods of time, the hip flexors become weaker and tighter. Over time, this can cause postural problems like posterior tilt.

By opening up the back angle of a chair, you allow the hip flexors to stretch.

Having a chair that allows you to change the backrest angle throughout the day keeps the hip flexors active and helps correct posterior tilt by lengthening the muscles.

A chair with dual-motor tilt-in-space is ideal for this.

The seat and backrest initially tilt together. The user can then open the backrest angle out further to lie back more.

3)     Adjustable footrest


We’ve already covered the importance of seat height for someone with posterior tilt. Their feet must be properly supported.

So, if you’re using a footrest or footplate, it is equally important that it’s the right height too! Too low and the user will slouch forward. Too high and it can impact hip flexion by pushing the knees up too high.

The footrest is even more important if someone’s posterior tilt is linked to tightness in their hamstrings.

The hamstrings are a group of muscles in the back of the thigh, connecting the hip to the knee.

If tight hamstrings are an issue, consider a negative angle footrest. That’s a footrest that folds back under the seat. This can help to stretch the hamstrings and reposition the pelvis, reducing posterior tilt.

Lento footrest

The footrest on the Lento Care Chair can be readjusted to give a negative leg angle

Adjustability is key

You might have noticed a recurring theme here — adjustability!

To prevent and treat posterior tilt, seating must be adjusted to fit the individual user. There’s no one-size-fits-all solution.

We have two top choices for posterior tilt — a Made-to-Measure Riser Recliner and the Lento Care Chair. Both chairs can offer exceptional comfort and support for postural abnormalities. Seat sizing can be tailored to the individual user and the backrest angle can be adjusted to allow flexion of the hip joints.

The best option comes down to how mobile the person is. For someone with posterior tilt who is still able to stand and walk, go for the Rise and Recline Chair. For someone who is immobile and requires hoisted transfers, go for the Lento instead!

Other postural abnormalities

Posterior tilt is one of many common postural abnormalities. We’ve written detailed guides on other conditions too! Take a look to see how specialist seating can help with:

Posture & Seating Assessment

For more advice on specialist seating and postural abnormalities, please book a free assessment!

Our specialist team have over 30 years’ experience and will be more than happy to help.

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Date Published

25 September 2020

Reading Time

6 minutes

Author avatar


Graeme Wilson

Graeme has worked alongside the public sector for much of his working life, helping departments improve efficiencies and deliver on projects. In his role at Vivid.Care, Graeme used his experience to tackle some of the most challenging issues in the healthcare sector, from falls through to winter pressures. He was also a guest speaker and a number of different conferences, including at the Falls Prevention Summit in London.

pelvic diagram

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