Radiological testing: Plain X-rays

Diagnostic tests Medical history and physical examination Radiological texting Plain X-rays CT Scan (Computed Axial Tomography) Magnetic Resonance Imaging (MRI) Radionuclide imaging Discography Myelography Neurophysiological testing Blood tests Other diagnostic tests

What it is:

It consists of radiating a patient with X-rays. These cross, in lesser or greater extent, through different types of tissues depending on their content of gas, liquids or solid elements. For example, they more easily cross the muscles and the bones. Placing the patient between the source of X-rays and a negative plaque, the formed image allows vertebrae identification, evidencing their alignment, and gives a general idea of vertebral or other surrounding tissue composition.

What it allows:

Basically, plain X-rays give information on the silhouette of the spinal column and permit the physician to rule out a diagnosis of common back pain. They allow detection of:

• Pathology that causes back pain but is not common back pain; infections, tumors, vertebral fractures or signs of osteoporosis (loss of bone mass). The existence of some of these disorders rules out common back pain.
• Spinal curve variations, such as scoliosis. In this case, it allows precise quantification of the curvature.
• Some organic spinal anomalies: spondylolisthesis and facet arthritis. In vertebral arthritis they permit the observation of the presence of osteophytes, important disc degeneration, in which the nucleus pulposus has practically disappeared and has been substituted by air -this phenomenon is known as "discal vacuum"- and, in its initial phases, vertebral approximation as a consequence of a degenerative process of intervertebral thickness loss (formerly known as disc narrowing). Plain X-rays do not allow diagnosis of fissures, protrusions or.herniated discs, or postoperative fibrosis.

The usefulness of conventional radiology in mechanical pathologies is quite limited since, as stated by the existing recommendations based on scientific evidence:

• Back pain is usually due to causes not evidenced in plain X-rays, and
• Most anomalies detected by plain X-rays are abnormalities that do not increase the risk of suffering back pain, and evidencing them does not cause any changes in treatment strategy.

A study following the evolution of a group of teenagers with spinal anomalies detected by plain X-rays, showed that they did not present back pain more often than those youngsters with normal X-rays, neither at baseline nor in the following 25 years.

Risks

Conventional radiology is not painful but X-ray radiation is potentially harmful, therefore its use should be limited only to justifiable cases. Some of the existing recommendations based on scientific evidence indicate that lumbar spine X-rays involve 150 times the radiation dose of a chest X-ray.

Indications

The existing recommendations based on scientific evidence consider that:

• There is no indication for routine X-rays in acute back pain of less than 4 weeks, except in the presence of data suggestive of pathologies other than common back pain or signs of nerve compression.
• Plain X-rays are indicated to rule out the presence of general diseases causing back pain which are not directly associated with the spine -that is, not common back pain-, such as tumors, infections, fractures or vertebral crushing. In these instances, it may be wise to perform plain X-rays if:

1. The patient's previous history, pain characteristics or physical examination, suggest this type of pathology.
2. Pain persists after the first month of treatment.

It is worth saying that X-rays should be done only once, trying to avoid repeated radiographs. In fact, some of the existing recommendations based on scientific evidence specifically advise avoiding unnecessary or repeated X-rays.

In instances of bone fractures with non-displaced fragments, an X ray needs time to show signs of fracture. If trauma is recent, the fracture may not be seen with X-rays, and a bone scan may be necessary.

Although the existing recommendations based on scientific evidence make no specific mention of this, it may prove useful to perform X-rays in infantile or juvenile scoliosis to enable an adequate follow-up and assessment of the eventual progression of the curvature grade. In these cases, individual periodicity for performing X-rays must be assessed; periodicity should be spaced in time as much as possible, taking into account the scoliosis progression rate and the child's age and sex.