Medical conditions affected by posture

As you will know, sitting with a neutral spine is important for any patient with a medical condition involving the lumbar spine.

Here is a quick recap of the effects of sitting slumped.

In the lumbar spine:

  • the lumbar spine is flexed
  • the posterior spinal structures are passively stretched
  • the internal intervertebral disc pressure increases posteriorly
  • there is a slight anteroposterior (A-P) sheer force of the vertebra above on the vertebra below in the lower lumbar spine

Other consequences:

  • the pelvis rotates posteriorly
  • the hip angle increases a little
  • the thoracic and/or cervical spine will want to extend to compensate for the loss of lumbar lordosis
  • the diaphragm’s action will be impaired
  • intra-abdominal pressure will rise
  • venous blood will tend to pool in the pelvis

We’ve put together some information below about a number of medical conditions which can be improved when patients sit correctly.

Spinal conditions

Ankylosing spondylitis (AS) – it is very important that patients with AS habitually sit with their normal lumbar lordosis (arch). AS can try and fuse the lumbar vertebrae and it will do this in the shape that is adopted most frequently. If the patient spends long periods of time sitting in a slumped shape, they will lose their lordosis and they will end up with a forward stooped posture.

Autoimmune arthritis for example: rheumatoid arthritis (RA)
These are all inflammatory joint conditions and when affecting the spine, they are irritated with poor sitting.

For patient help go to – https://www.arthritis.org.nz/

Disc lesion: Lumbar Intervertebral – irritation/herniation/injury – these might all be classified under the common heading ‘disc lesion’. Remember these are very common and most people will go to their deathbeds with one or more of these.

The presence of a disc lesion, even if highlighted by an MRI, does not automatically mean that the patient will have pain.

However, as disc lesions are known to be very common and low-back pain is also common, a connection between the two cannot be ignored.

Even when sitting in perfect spinal posture, the internal disc pressure in the posterior portion of the disc increases by 40% compared to standing. Sitting in lumbar flexion increases this pressure even more. The posterior portion of the disc is where the majority of bulges and herniations occur, so it is reasonable to assume that increasing this pressure will make them worse. Wilke (1999) & Nachemson (1981) .

Note – in patients with disc lesions and associated nerve root compression, some will be made worse by bending forwards and some will be the opposite, depending on the location of the lesion. Sitting with a spine as close to neutral is desired, as long as it does not compress the nerve root more.

Lumbar spine osteoarthritis (OA)– because this reduces the mobility of the lumbar spine, the posterior spinal structures come under tension earlier when slumping.

Sciatica – this is most commonly due to a bulging lumbar disc causing irritation of the sciatic nerve root (see Disc lesion). It can also associated with spinal stenosis (see Spinal stenosis) or a space-occupying lesion (SOL).

Spinal stenosis: Foraminal – the nerve roots are being compressed at the level of the spinal foramen (https://en.wikipedia.org/wiki/Spinal_stenosis).
Patients may report that they get relief of symptoms by bending forwards and aggravate their symptoms by bending backwards. Although sitting slumped might give short term relief, doing this excessively often aggravates the underlying cause of the stenosis. These patients need to sit with enough flexion, so that they have no compression of the nerve roots, but this must not be in maximum flexion. The difference between these two positions is often very small, and the lumbar support required to hold this shape must be strong.
Caution: the assumption here is that the condition is of a mechanical nature. If unsure seek an accurate diagnosis.

Spinal stenosis: Central – the diameter of the spinal canal has reduced and now exerts pressure on the nerve structures in the canal.
With these patients a sitting position must be found that puts the least amount of tension on the nerves being affected. The tension can often be altered by changing their leg position. This will vary from patient to patient. Commonly tensioning the sciatic nerve has the greatest influence on symptoms. To reduce pull on the sciatic nerve, look at increasing:

  • ankle plantar flexion
  • knee flexion
  • hip angle

These patients need to sit with enough flexion so that they have as few neurological symptoms as possible, but this must not be in full flexion. The difference between these two positions is often very small, and the lumbar support required to hold this shape must be strong.
Caution: Spinal stenoses may be a red flag for another pathology so accurate diagnosis is important.

Spondylolysis/spondylolisthesis – These are spinal instability conditions. Sitting slumped will tend to increase the instability.
Generally the first concern with these patients is to avoid excessive lumbar spine extension. Hyperextension of the lumbar spine is difficult while sitting, unless the lumbar support is too big.
Note – an accompanying feature of these conditions is very short hamstrings.

Surgery – Discectomy – Usually carried out to remove a bulge of the intervertebral disc that is pressing on a nerve root. Slumped sitting is a significant aggravating factor in producing these disc bulges in the first place. The most reliable predictor as to whether a patient will have a discectomy in the next 12 months , is if they’ve received one in the last 12 months. Therefore ‘perfect posture’ coupled with other rehabilitation management activities is imperative.

Surgery – Lumbar artificial disc replacement – Artificial disc replacement has been developed as an alternative to spinal fusion, with the goal of pain reduction or elimination, while still allowing motion throughout the spine. Another possible benefit is the prevention of premature breakdown in adjacent levels of the spine – a potential risk in fusion surgeries (see Spinal fusion below).

Surgery – Lumbar spinal fusion– the spinal joints are stabilised with an implant. This allows no movement over the spinal segments that have been fused, leading to a less flexible lumbar spine. The spine needs to be held in neutral so it can absorb forces and vibration efficiently and not put excessive and prolonged forces through the implant (they can break). The joints immediately adjacent to the fused level now have to work harder and because of this, they are prone to early degenerative change and premature breakdown. By maintaining a neutral lumbar spine, the chance of this is reduced.

OTHER CONDITIONS

Gastrointestinal (GI) disorders – GI disorders are made worse with poor gut motility. Gut motility is inhibited when sitting slumped.

Haemorrhoids – the link between haemorrhoids and prolonged sitting is well-established. Haemorrhoids are made worse by poor sitting habits. Sitting slumped encourages pooling of the blood in the pelvis because of static intra-abdominal pressure and inefficient diaphragm activity.
For patient help visit http://www.dealwithhemorrhoids.com/why-sitting-too-much-can-cause-hemorrhoids-and-what-you-can-do-instead/
Haemorrhoids are a common complaint amongst truck drivers. For some help visit:
https://www.hemorrhoidinformationcenter.com/truck-drivers-and-hemorrhoids/

Headaches – the posture described in Neck and upper shoulder pain (see below) can also cause headaches, which in turn can impair concentration.

Heartburn – gastro oesophageal reflux – slumped static sitting posture will make this worse.
For patient help visit: https://americanpostureinstitute.com/your-heartburn-isnt-just-from-your-food-its-from-your-posture/

Hip osteoarthritis (OA) – severe restriction at the hip joint in flexion will force the pelvis into posterior rotation to avoid hip pain. To increase the hip angle, raise the seat base and recline the seat back a little.
Note – a compromise might be needed here. Posteriorly rotating the pelvis will help the OA hip but might aggravate the lower back. Using a small degree of posterior pelvis rotation may be enough to alleviate the hip pain, but not so much as to aggravate the lower back.

Hypermobility disorders – e.g. Ehlers-Danlos or Marfan’s Syndromes. These syndromes are characterised by increased joint laxity resulting in joint instability. This will be worsened by poor passive loading.
For patient help visit – http://hypermobility.org/

Neck and upper shoulder pain – sitting slumped in the lumbar spine means that the upper trunk flexes forwards and the head faces down. Therefore, to look forwards, a driver must extend their neck and upper thoracic spine. This is the same as looking up at the ceiling the whole time. This can produce neck and upper shoulder/back pain.

Pregnancy – sitting slumped in pregnancy is generally discouraged as it does not allow the baby to move easily and it also puts yet more pressure on the mother’s organs.

Pregnancy – with pain in the low back pain or sacroiliac joint (SIJ). Driving almost always makes the pain with these conditions worse, especially if sitting slumped. Often being a passenger with no steering wheel to hold onto is worse than being a driver. The lateral forces on cornering are often very uncomfortable and so both lumbar support and lateral support are needed.

Respiratory conditions – sitting slumped compresses the abdominal cavity, reduces abdominal mobility and increases intra-abdominal pressure, all of which make it harder for the diaphragm to move. This discourages diaphragmatic breathing which will exacerbate any respiratory condition.

2018-11-12T11:21:37+00:00