Ultrasonography of the lumbar spine: sonoanatomy and practical applications

Ultrasonography of the bones and joints has gained considerable ground in the field of rheumatology over the past decade and is now used in everyday practice both for diagnostic purposes and to guide local injections. However, the use of ultrasonography is virtually confined to the peripheral joints, whereas spinal diseases make a major contribution to rheumatology practice. Studies have established that ultrasonography of the lumbar spine is feasible. Adequate equipment and familiarity with spinal sonoanatomy are required. In this update, we suggest starting with a systematic examination of the lumbar spine to assess the various anatomic structures, from the thoracolumbar fascia superficially to the posterior part of the vertebras at the deepest level. The ligaments, erector spinae muscles, facet joints, and transverse processes can be visualized. Ultrasonography can serve to guide injections into the facet joints, about the nerve roots, and into the iliolumbar ligaments; as well as to identify relevant landmarks before epidural injection. Although diagnostic applications are more limited at present, systematic studies of abnormal ultrasonography findings will allow evaluations of the potential usefulness of ultrasonography for diagnosing spinal disorders. The depth of the spinal structures limits the ability to obtain high-resolution images. However, future technical improvements in ultrasound transducers and machines, together with the growing number of physicians trained in ultrasonography, can be expected to benefit the development of spinal ultrasonography in the near future.