Back or hip pain radiating down the leg is primarily caused by nerve compression in the spinal canal of the lumbar spine. Accompanying symptoms can include numbness or weakness. Severe nerve compression in the spinal canal might result in difficulties controlling urination or defecation. The primary causes of this nerve compression are:

• Herniated disc, also known as lumbar disc herniation or slipped disc
• Spinal stenosis
• Spondylolisthesis, also known as slipped vertebrae

In a smaller number of cases, the issue can stem from:

• Spinal fractures resulting from high- or low-energy trauma
• Spinal infections
• Spinal tumors

Pain severity can range from mild to severe, and may extend from the hips to thighs, calves, feet, and ankles. Some patients also experience numbness or weakness. Some might experience pain radiating down their legs after walking long distances, causing them to stop (claudication). Symptoms tend to worsen when weight is applied to the spine, such as during sitting or walking, and improve with bed rest. It is also essential to watch out for "red flag" symptoms like fever, loss of appetite, weight loss, or nocturnal pain (pain that awakens you from sleep).

To determine the cause of nerve compression in the back, a Magnetic Resonance Imaging (MRI) test is often performed. An MRI can reveal the pathology compressing the nerve and identify the location and severity of the nerve compression. This test might be considered in conjunction with a plain X-ray.

Treatment strategies depend on the underlying cause of the nerve compression. They typically include:

• Lifestyle modifications
• Medication
• Physical therapy
• Epidural steroid injections
• Surgery, when indicated