Leg Pain: Is It from My Back or Hip?

Low back pain is the second most common reason people seek medical care. Pain radiating or traveling to the leg is one of the symptoms these people experience. When they present with leg pain without significant back pain, it causes a diagnostic dilemma to the treating physician as the pain could be radiating from the back or hip. Making an accurate diagnosis is essential as it will determine the treatment plan. The right treatment will ultimately result in improving the quality of life by minimizing pain and helping to resume an active lifestyle.

Hip disorders as a cause of leg pain

When the hip joint is affected, people commonly present with complaints of groin pain on the affected side, reduced range of motion of the hip, anterior or medial thigh pain, knee pain, or buttocks pain. The pain usually does not go down below the knee and there is no associated numbness or tingling. The pain worsens on walking or standing, and is better with rest. The limitation of range of motion is felt when trying to get out of the car, chair, or bed. Occasionally, pain in the hip could be secondary to inflammation of a hip bursa. This commonly is the result of tight hip abductor muscles, difference in leg length, or hip arthritis. Hip pain can also be due to serious causes like fractures, tumors, infection, or aseptic vascular necrosis, which should not be missed as they occur uncommonly.

Back disorders as a cause of leg pain

Pain coming from the back or the lumbar spine is commonly referred to as sciatica. It is important to understand that sciatica is a symptom and not a diagnosis. This could be secondary to multiple causes. The common disorders of the spine causing back and leg pain are disc disorders such as herniated or ruptured disc, nerve root compression, and arthritis of the facet joints in the spine. Usually, pain is accompanied by numbness and tingling. When patients have narrowing of the canal through which the nerve root travels down from the spine to the leg, they present with similar complaints. This is called lumbar spinal stenosis. Back pain could also be secondary to sacroiliac joint dysfunction or piriformis syndrome. These different causes can be differentiated by the treating physician with a good history and physical examination as each cause has a slightly different presentation.

Diagnosis

As people are different and do not present exactly as described in the literature, it becomes difficult to make an accurate diagnosis when it comes to differentiating hip and back disorders as a cause of leg pain. Commonly, if examining the hip joint causes no hip pain, but examining the back reproduces leg pain, then it is usually the spine that is the cause of the problem. There are some people who present with localized hip pain but are found to have a normal hip but an abnormal spine. Then there are other people who present with only leg pain, who are found to an abnormal hip and a normal spine.  Therefore, it is essential to do radiographic investigations in addition to a good physical examination. Plain X-rays may help to differentiate the cause. Both hip and lumbar spine X-rays can be abnormal in the elderly and may show presence of arthritis. In such cases, an MRI is essential as it can evaluate the anatomical structures in detail. It is also important to remember that these images show only the anatomy and do not report if the structures are the source of pain. In such difficult cases, the next step would be to perform an injection using a local anesthetic with or without cortisone into the hip joint under fluoroscopic or X-ray guidance. If the pain remains the same then it can be concluded that the hip joint is not the source of pain. The next step would be to perform an injection to the spine, which could be an epidural steroid injection if nerve root irritation is suspected or a facet joint injection if you suspect arthritis as the cause of pain. Injections are excellent aid in determining the origin of the pain.

Treatment

Whether the source of pain is the hip, sacroiliac joint, piriformis muscle or the lumbar spine, the initial treatments are the same if the pain is mild to moderate.  These include the use of anti-inflammatory medications, physical therapy, and injections. If people are unresponsive to these treatments then surgery is offered if they have a significant structural pathology. I want to emphasize that it is critical to make an accurate diagnosis before a treatment can be successful. Therefore, if you experience leg pain, make sure to get it evaluated.