Acute Low Back Pain

Acute low back pain is usually a result of damage to a disc or a nerve, with subsequent protective muscle spasm.

The discs sit between each vertebra in the spine and are similar to the cartilage in the knee. Their function is to allow movement of individual segments of the spine; aid the spine in weight-bearing; shock absorbance; transmission of force from spine to pelvis to legs.

Discs are made up of two different substances: the firm outer ring, known as the annulus; the semi-fluid interior, known as the nucleus. The main constituent of the nucleus is water, but this decreases with age making it firmer.

The most commonly injured discs are the bottom two – L45 and L5S1. Damage is either by sudden or repetitive trauma. Examples of repetitive trauma are twisting and/or bending activities. Often, the activity to actually cause the injury is very innocuous, for example, bending to tie a shoe lace, or coughing. However, it is what has happened previously that sets the disc up for damage, such as prolonged sitting in a slouched posture.

The damage can cause a tear in the annulus. In severe cases, this can be right through the ring. The nucleus material can then flow in to the tear, pushing the wall of the annulus outwards, encroaching on the surrounding structures. This will create inflammation and swelling. The common term for this condition is a “slipped disc”, although the disc merely bulges – it does not slip out of position! In a severe case, where the annulus has torn right through, the nucleus material flows out of the disc directly into the surrounding structures.

As discs lose their water content with age, “slipped discs” are more commonly seen in a younger population when the nucleus still has the ability to flow.

Symptoms depend on which direction the disc is bulging in, what structures it is encroaching on, and to what extent. Common symptoms are:

  • low back pain
  • referred pain into the buttocks, legs, feet
  • muscle spasm
  • loss of movement
  • numbness and/or pins and needles in the legs/feet

Referred pain is not necessarily a result of the disc compressing a nerve – all structures in the spine including the discs themselves are capable of referring pain.

Symptoms are commonly aggravated by sitting, bending or stooping activities, lifting, coughing, and sneezing.

Nerve damage is most commonly caused by a “slipped disc” as the disc bulges on to a nerve. However, it can also occur with arthritis in the joint through which the nerve runs, as excess bone from the arthritis pinches the nerve. Acute trauma can also cause the nerve to be pinched within the joint.

Symptoms are similar to above. The main difference is the type of pain: it is a sharp, shooting pain that radiates in a narrow band. As well as numbness and/or pins and needles, there may be some weakness in the leg muscles.


Seek medical advice ASAP. Initially, the priority will be to reduce the pain and muscle spasm. This can be done by avoiding any aggravating postures and activities, rest (although only for 1-2 days) and painkillers/anti-inflammatories – discuss with a doctor or pharmacist before taking anything.

Physiotherapy is beneficial – the earlier the better to ensure you are doing all the right things! Treatment will:

  • decrease pain
  • decrease muscle spasm
  • decrease inflammation
  • promote healing and repair
  • increase movement and flexibility
  • restore normal function

You will be given advice on the best postures to adopt and how to look after your back in order not to aggravate the symptoms or worsen the condition. The physiotherapist will discuss with you when and to what extent you can resume normal daily activities. Advice on prevention of recurrences will also be offered.

One of the best ways to prevent re-injury – asides from maintaining good posture and back care – is Pilates. This is a gentle set of specific exercises designed to strengthen the muscles that support the spine, similar to scaffolding. It is advisable to ensure that the Pilates instructor is well qualified with an understanding of teaching people with back complaints. For further advice on this, please contact the physiotherapist at the Gingerbread House.

For further advice please contact Radlett Physiotherapy on 01923 857338.

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