Low Back Pain and Effects of Lumbar Hyperlordosis and Flexion on Spinal Nerves

Lumbar hyperlordosis is 50% more accentuated with standing rather than sitting. This may cause nonspecific LBP localizing to somatic tissues (e.g., paraspinal muscles, facet joints) mediated by inflammatory mechanisms. In extreme hyperlordosis, exiting nerve root entrapment secondary to intervertebral foramen narrowing with this posture may cause radicular irritation or a frank radiculopathy with sensorimotor deficits. Patients with lumbar spinal stenosis (LSS) have reduced anteroposterior central canal and lateral recess dimensions with hyperlordosis. Associated compromise of microvascular perfusion of the cauda equina possibly accounts for posture-precipitated pain while standing and walking, known as neurogenic claudication (NC). LSS nerve root injury may cause radicular pain characterized by sharp, lateralized pain conforming to dermatomal distributions, a radiculopathy, or NC. Straigh-tleg raising stretches the sciatic nerve, simulating radicular traction that provokes pain in an inflamed or otherwise sensitized nerve root.

In the lumbar spine, the primary motion is flexion/extension with very little segmental rotation. Lumbar flexion opens the foramen more widely, reducing nerve root compression. The amount of compressive force and tension on the nerve root decreases with spinal flexion and increases with spine extension.

Lordosis typically occurs maximally at L4-S1. A simple radiographic image to determine the postural status may capture the extent of lordosis. The normal range of lumbar lordosis is 20 degrees to 50 degrees, whereas hyperlordosis is defined as greater than 60 degrees. LSS patients have physical examination findings denoting loss of lumbar lordosis. Another test for NC is the stoop test; here the patient walks with an exaggerated lumbar lordosis until NC symptoms appear or are worsened. The patient is then instructed to lean forward at the waist; reduction in symptom intensity is considered suggestive of NC.

A radiographic study of sagittal lumbar spine measurements of 552 asymptomatic subjects with lordosis found that, in pain-free subjects, 65% of lordosis occurs between L4-5, and 35% occurs above L4. This study also demonstrated that hyperlordotic patients tended to have acute low back pain, whereas chronic low back pain patients were hypolordotic, emphasizing the importance of hyperlordosis in chronic LBP individuals.

A systematic review of randomized clinical trials of conservative treatment for acute and chronic low back pain (CLBP) supports the use of muscle relaxants, nonsteroidal anti-inflammatory drugs (NSAIDs), acetaminophen, manipulation, and active exercise therapy in the treatment of acute LBP. Hyperlordosis is not always associated with painful symptoms, and this, per se, is not an indication for treatment. Analysis of chronic LBP therapies have shown stronger evidence of the effectiveness of exercise and manipulation therapy as compared with behavior therapy. NSAIDs may accelerate the process of returning to usual activities or work. Of interest, other popular treatment options, including transcutaneous electrical nerve stimulation (TENS), electromyographic biofeedback, acupuncture, and orthoses are not proved to be useful.

Conservative treatment, such as physical therapy, is recommended for patients with LSS or hyperlordosis. Lumbar extension exercises should be avoided in these patients because spinal extension and increased lumbar lordosis are known to worsen LSS. Flexion exercises for the lumbar spine are emphasized because these methods increase the spinal canal dimension and decrease stress on the spine, thereby reducing lumbar lordosis. Strengthening exercises include back hyperextensions, hip flexor, and gluteus and hamstring stretches, along with abdominal exercises. Avoiding sedentary lifestyle, such as sitting for long periods of time, or wearing a lumbar brace may also be helpful. Short-term pain relief can be achieved with the use of NSAIDs. A study published in 2005 demonstrated the greater benefit of Iyengar yoga (significant reduction in self-reported disability and pain, and reduced use of pain medication) than educational programs in the management of CLBP patients. For CLBP, positions that include twists and inversions may alleviate hyperlordotic pain. Twisting motions involve the deeper layer of back muscles and reduce the pain symptoms by realigning the vertebra, increasing intervertebral disk space, and decreasing possible impingement of nerve roots, whereas inversions reverse the compressive effects of gravity on the intervertebral disk space.

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