If you experience pain and irritation in your lower back that radiates to the legs, it could be due to sciatica. It is a common disorder affecting the bones and joints. However, the manifestations of this condition are related to the involvement of the nerves and muscles.
The incidence of sciatica is increasing at an alarming rate over the past few years. The rising incidence could be attributed to obesity, sedentary habits, and lack of adequate physical activities. 
Hence, it is important to be aware of the causes and risk factors of sciatica so that you can take the necessary steps to avoid the development of this condition.
What is sciatica and why it occurs?
Sciatica refers to nerve pain that usually occurs following irritation or injury to the sciatic nerve. This disease nerve originates in the lower part of the spinal cord. It passes through the gap between 2 adjacent lumbar vertebrae and follows the course along the back of each leg. 
The sciatic nerve is the thickest and longest nerve in the body. It is made of 5 nerve roots coming together to form the left and right sciatic nerves. Each nerve runs along your hips, and buttocks on each side of your body and then, passes down a leg, finally ending just below the knee. 
What are the risk factors for sciatica?
It is estimated to affect nearly 40% of adults at some point during their lifetime. Back pain due to sciatica is also the third commonest reason why people visit a healthcare provider.
Several factors can contribute to the risk of sciatica such as:
- An injury to the lower back or spine can put you at risk of sciatica.
- The age-related degenerative changes occurring in the vertebral column can trigger the development of sciatica. Hence, the risk of this condition increases with age. The aging processes cause natural wear and tear of the bones and discs in the spine. As a result, the vertebral bodes fall on to each other causing compression of the sciatic nerve. 
- The incidence of sciatica is higher in obese people. The risk of complications associated with this disease is also more in people who are overweight. Obesity increases the risk of sciatica due to the increased pressure exerted on the spinal cord.  The vertebral column is like a crane and the muscles in the back are the counterweights that support the vertebral bones. The weight in front of your body has to be lifted by your spine by working as a crane.
- Obesity increases the amount of weight the muscles in the back have to carry. This can put more strain on the back muscles resulting in wear and tear of these tissues. It would cause a collapse of the vertebral bones and discs over each other leading to the faster development of sciatica. 
- Lack of a strong core is one of the risk factors for this disease. The “core” refers to the muscles in the abdomen and back. A stronger core can provide better support to the spine during physical activities. However, a weak core can make the vertebral column vulnerable to strain thereby increasing the risk of sciatica.
- The incidence of sciatica is more in people who need to lift heavy weights regularly. It may increase the strain and pressure on the back muscles and spinal cord and even trigger the backward bulging of the intervertebral disc. It usually happens when a person suddenly lifts a very heavy object by holding his breath. Holding the breath causes an increase in the abdominal pressure due to which the intervertebral discs between 2 adjacent lumbar vertebrae may get forced backward. The disc may touch or press on the sciatic nerve arising from that part of the spinal cord causing it. 
- Lack of physical activities can cause stiffness of the muscles in the back reducing their ability to withstand the strain. This is a common cause of sciatica is computer professionals. 
- Failure to maintain correct posture while sitting, walking, or running can also exert undue pressure on the back muscles and lead to this disease.
- The indicine of sciatica is higher in people with uncontrolled diabetes. Diabetes can also increase your risk of complications by worsening nerve damage.
- Osteoarthritis that occurs due to the inflammation and degenerative changes in the joints can cause damage to the spine and put the nerves at risk of injuries. Hence, patients with osteoarthritis are more likely to develop it.
- The risk of sciatica is higher in smokers than in non-smokers. The risk could be attributed to nicotine in tobacco that can cause damage to the spinal tissue, weaken the bones, and speed up the wear and tear of vertebral disks. 
- Women are more likely to develop this disease during pregnancy due to weight gain and the increased strain on the back muscles. Also, some hormones secreted in the body during pregnancy can make the ligaments weaker. The ligaments protect the discs and hold the vertebrae together, thus keeping the spine stable. The loosened ligaments may make the spine unstable and cause the intervertebral discs to slip or bulge backward. This may lead to the sciatic nerve being pinched resulting in the development of this disease.
Some disorders that are known to increase the risk of sciatica include:
- Degenerative disk diseases such as spinal stenosis
- Spondylolisthesis occurs due to the slipping of a vertebra resulting in the misalignment of the spinal column
- A tumor in the spinal cord that compresses the sciatic nerve
- Piriformis syndrome that develops due to the spasm of the piriformis muscle in the buttocks
- Cauda equina syndrome that affects the bundles of nerves present at the end of the spinal cord
The pain and discomfort caused due to sciatica can limit your activities to a great extent. If not diagnosed and treated properly, the compression of the sciatic nerve may become worse resulting in the paralysis of the muscles of the legs.
Hence, it is important to be aware of the causes, risk factors, and initial warning signs of sciatica. It is possible to prevent this disease or its complications by following a healthy lifestyle and seeking early medical intervention.