Eighty per cent of low back pain is due to over stressing the various structures in the lower back, i.e. the discs, ligaments, joints or nerves. This pain may be a deep aching pain, a burning pain or a twinging pain. Other associated symptoms may include numbness, pins and needles, and coldness or weakness in one or both legs. It may be felt in the back alone, in the back and one or both legs, or just in the legs. If the pain is felt in the leg it is a sign of more serious trouble and you should seek help from your physiotherapist or doctor immediately.
Example of Pain Due to Mechanical Stress
Hold your index finger back until you feel a strain and then hold it there for a few minutes (See Fig 1). It will soon start feeling sore not only around the joint but the pain will spread further afield. Imagine if you did that to your back when sitting in a slouched position for a long period of time.
Getting to Know Your Spine
Your spine is composed of 24 bones called vertebra, which are separated in the front by a shock absorber called an intervertebral disc and at the back by the facet joints. Through a hole in each vertebrae runs the spinal cord, sprouting nerves that lead to other parts of the body. The spine has five sections; the cervical spine or neck, the thoracic spine, the lumbar spine, the sacrum and the tailbone or coccyx. (see fig 3)
The Vertebrae (see Fig 2.)
The vertebrae are building blocks, they house and protect your spinal cord. You can feel them if you run your fingers up the middle of your back. Your vertebrae may be responsible for back pain when:
- One is fractured due to the application of strong enough forces
- Physical stress over a long period of time causes the shape of your vertebrae to change (poor posture)
- Certain diseases or conditions weaken them e.g. Osteoporosis, Scheuermanns disease.
The Facet Joints
Facet joints are formed by the overlapping of two vertebrae and are designed to help guide the movement of your spine. Pain from the facet joints is usually due to strain and inflammation of the joint which may in later stages lead to degeneration and arthritis. This can be caused by:
- Overstressing, either slowly as in repeated twisting movements or by habitually adopting poor posture
- A quick unprotected movement or fall
The Intervertebral Disc
The disc sits between two vertebrae. It has a jelly like centre which acts as a shock absorber as well as allowing movements of the spine. Injury to the disc can occur with:
- Abnormal forces being applied to the disc causing it to tear or rupture, e.g. bending forward and twisting, lifting incorrectly etc
- Wear and tear to your disc, causing the supporting ligaments to weaken leaving the jelly like center to create a bulge in the disc
Herniated or Ruptured Disc
If the bulge in the disc is big enough it can put pressure on adjacent sensitive structures causing pain and other symptoms e.g. numbness and pins and needles. Disc pain is commonly felt as a deep aching pain either in the back alone or down the leg.
The nerves leave the spinal cord through holes between the vertebrae. These nerves can be pinched by a herniated disc, inflamed facet joints or bone spurs (see figs 4&5).
Injury to a nerve may give rise to a burning pain, pins and needles, numbness or weakness in the affected leg. Coldness or heaviness may also be experienced in the affected leg.
The lumbar spine is supported in front by your abdominal muscles and at the back by your spinal muscles. As a result of poor posture, injury or bad habits an imbalance between these two muscle groups can occur. The body then loses its natural balance and the various structures of the spinal column become over stressed. This is often felt as pain on prolonged standing.
The ligaments are strong fibrous bands which hold the vertebrae together, limit their motion as well as protect the disc. These ligaments are most commonly injured by too much stress as in bending and lifting or by prolonged stretching as in slouched sitting. (see fig 6).
REMEMBER: If pain is felt in the leg it is a sign of more serious trouble and you should seek immediate help from your physiotherapist or doctor.
It is important to have a good understanding of the effect that posture and movement have on your back. As there are many different types of back problems it is essential that you understand what will benefit your particular back problem.
The postures and movements which reduce or bring the pain into the middle of your back are the correct ones for you. If the pain moves down into your buttocks or legs then it is the wrong movement or posture for your back. Keep this in mind when reading about the preventative measures below.
LET PAIN BE YOUR GUIDE
Causes and Prevention of Back Pain Sitting
Most people, if they have to sit for a long time will eventually slouch, loosing the natural inward curve (fig 7), or lordosis of the lower back. This results in stressing the structures in the lower back which over a period of time will eventually cause pain. At first you may only experience pain when sitting. If you continue to slouch day-in day-out you may find standing up painful. You have to walk in a stooped position before being able to stand upright.
How to Help Your Back
It is important to sit in the correct posture whether as a preventative measure or to relieve stress on an already painful back. You must keep the natural (not exaggerated) inward curve or lordosis in your back (Fig 8). Maintaining good posture in a chair with a back rest is made easier with a lumbar roll. A lumbar roll is an specially designed cushion (fig 8) which provides support for the back when sitting and is available from most physiotherapists.
Should you have an exaggerated lordosis in your lower back or an exaggerated roundness/hump in the area of your shoulder blades you may find that a lumbar roll does not help. In this case support in the area of your spine between your shoulder blades may help.
If sitting for a few hours, take regular breaks to reduce the stress on your back. This should be done before any pain starts. Stand up and walk around. You may find that putting your hands in your back, and bending backwards 5 or 6 times (slowly and smoothly (fig 11.)) helps any stiffness you feel in your back after sitting. It is important to maintain good sitting posture after any sport or vigorous activity as the spinal structures are particularly susceptible to stress at this time.
Lifting with your back rounded puts a lot of stress on the structures of the lumbar spine. Your spine is particularly at risk when:
· Lifting heavy objects.
· After prolonged periods of sitting (e.g. after driving).
· In the first 4-5 hours of the day.
It is important when lifting to keep the natural inward curve of your back.
- Stand close to the load with your feet apart, creating a stable base.
- Keep the natural inward curve of your back, bend your knees and go down to the load.
- Get a secure grip on the load and tighten your stomach muscles. You may have to lean back slightly depending on the load.
- To lift the load, straighten your knees.
- Don’t jerk, lift in a steady and controlled manner.
- If you have to turn, use your feet, do not twist your back.
- Put the load down by bending your knees and keeping your back straight. See fig 10
Working in Stooped Positions
Working in stooped positions is necessary in certain occupations, i.e. plumbers, surgeons, builders mechanics, mothers etc This places a great deal of stress on the lumbar spine and should be minimized where possible. Where possible you can minimise the amount of bending in your back by bending more at the hips.
How to Help Your Back
When you habitually work in stooped positions, interrupt your work at regular intervals, before the pain starts. Stand upright, put your hands in your back, and bend backwards slowly and smoothly 5 or 6 times.
Repeat this procedure every 15-30 mins.(Fig 11.)
REMEMBER LET PAIN BE YOUR GUIDE
Poor standing posture can be a contributing factor to low back pain. The three most common examples of this are shown here. It is therefore important to maintain correct posture:
- Stand with your weight evenly on both feet.
- Stand as tall as possible
- Pull your stomach in to maintain a normal (not exaggerated) inward curve in your lumbar spin
Lying and Resting
When lying and resting it is important that your spine is fully supported.
Your mattress should support your back so that when you lie on your side your hips and shoulders sink into the mattress just enough to keep your spine straight. Ensure your mattress does not sag or is not too hard.
If you think your mattress is too soft, try putting it on a firm hard surface (the floor is the easiest) or if it is too hard this can be helped by placing a sponge rubber topper pad on top of the mattress.
Choosing a Good Resting Position
Choosing a good resting position for your back will depend on the nature of your injury. Above are various options for resting. LET PAIN BE YOUR GUIDE when choosing the best resting position for your back. If you have trouble finding a comfortable position please ask your physiotherapist.
NB Lying on your stomach can ( but not for everyone) be a good resting position for your back but it is not advisable to sleep in this position.