Anatomy of the Lumbar Spine

The spinal column consists of circular bones (vertebral bodies) separated by cartilage discs (intervertebral discs).  The spinal cord runs through this column and gives off branches (nerve roots) between the vertebral bodies. 

The spinal column consists of circular bones (vertebral bodies) separated by cartilagenous discs (intervertebral discs).  The spinal cord runs through this column and gives off branches (nerve roots) between the vertebral bodies.  These nerve roots then join together to form the three major nerves that supply sensation to the lower leg.  

These are:  

• Femoral nerve 

• Obturator nerve 

• Sciatic nerve 

​

‘Sciatica’ is the medical term for pain that goes down into the leg. Patients often describe pain in the lower back as well as pain going down or radiating down the leg to the ankle and foot.  

​

Pain that is mainly localised to the leg it is called "leg dominant pain."

Causes of Leg Pain

Leg pain or sciatica is caused by pressure or inflammation of the nerve roots as they come out of the spinal column.  (See picture and MRI scan below.)  The causes might be:  

​

• Direct pressure from a prolapsed or herniated intervertebral disc.  (This is often called a "slipped disc.")

• Pressure because of narrowing of the spaces through which the nerve roots travel out of the spine (foraminal stenosis).

• Inflammation because of leakage fluid from the intervertebral disc.

• Pressure from a broken or crushed vertebral body (collapse fracture from trauma or osteoporosis).

• Pressure and inflammation from either an infection or cancer.

The symptoms of Leg Pain

The nerve roots supply specific areas of the leg.  This is called the dermatomal pattern and it is illustrated below.  The location of the symptoms will depend upon those nerve root(s) that have been affected.

​​

• Pain running down the lower limb.  This pain might be in the buttocks, the upper and lower leg and down to the ankle and the foot.

• Weakness of the lower leg muscles and foot.  This is called "foot drop" and patients often describe tripping up when walking.

• Numbness of the skin of the lower leg and foot.

• Pins and needles and a tingling sensation (paraesthesiae) in the lower leg, ankle and foot.

• Impotence in men

​

• The loss of bladder and bowel sensation.  This is a serious and dangerous symptom and a patient must see immediate medical advice from a doctor or suitable medical facility.

The diagnosis of Leg Pain

History:  

The diagnosis of the condition is usually made from the patient’s description of the symptoms.  The location of the symptoms (dermatomal pattern) will point to which nerve root is involved.

Physical examination: 

This might show weakness of the lower leg muscles, numbness in the involved area, and absent tendon reflexes at the knee and / or ankle.

It is essential to carry out a rectal examination to assess sensation and muscle tone if a patient described loss of bladder and / or bowel sensation.

Magnetic resonance imaging (MRI) scan of the lumbar spine:

This is the most commonly used investigation.  It would confirm the location of the herniated disk and show which nerves are affected.

Computerised tomography (CT scan):

This uses X-rays to create a cross-sectional image of the spinal column and the surrounding structures. 

X-ray images: 

A conventional single picture X-ray of the spine might demonstrate a collapse fracture of the vertebral bones.

The treatment of Leg Pain and Sciatica

See PDF Treatment Options Chart

1.         Conservative therapies: 

It is essential to use simple and conservative therapies first.  These would involve:

Medications:

​

• Simple painkillers such as paracetamol and codeine and the anti-inflammatory drugs (ibuprofen, naproxen).

• Stronger morphine-related painkillers (tramadol and morphine) are used on occasions for severe pain.  These are potentially habit forming and can have distressing side effects. Their use is usually discouraged and these should not be used in the long-term.

• Drugs to treat neuropathic pain (amitriptyline, gabapentin, and pregabalin).

​

Complementary and physical therapies:

​

• Physiotherapy

• Regular exercise (such as walking, cycling and stretching)

• Topical therapies such as anti-inflammatory rubs or gels (Voltarol Emulgel, Mobilat, Ibulieve) and hot or cold pads.

• A TENs Machine

• Acupuncture

• Joint supplements (Glucosamine)

​

2.         Interventional therapies:     

​

These involve injection therapies and surgical operations. 

​

Nerve root block injections (Transforaminal epidural steroid injection.)  

​

•   This involves using X-rays to inject local anaesthetic and cortisone (steroids) around the affected nerve root.  (See X-ray image and diagram below.)  This would treat the symptoms (therapeutic intention) and identify the source of the problem (diagnostic intention).  

Lumbar epidural steroid injection:  

​

• This is an injection of local anaesthetic and cortisone (steroids) around the nerve roots in the epidural space as they travel down through the spinal canal.

• Surgery to remove the prolapsed disc: 

  • There are various operations that might be carried out. The intention would be either to remove the prolapsed disc or relieve the narrowing caused by the ‘wear and tear’ process.  The precise operation and technique of the surgery would be explained to the patient by the operating surgeon.