Back Exam: X-Rays

X-Rays is the most common back exam ordered by physicians following a physical examination, to determine the cause of back pain.

If you experience either acute back pain or chronic back pain, the first person that you will likely see for your condition is either an emergency room doctor or a primary care physician. Either doctor will likely give you a physical examination to test for the activity of your muscles, reflexes, nerves, and possible soft tissue tears. In most cases, the doctor will make the determination that you don't have a serious back problem, and he will send you home with the conservative treatments such as the recommendation for icing, rest, and anti-inflammatories.

In other cases, the doctor may want more testing. X-rays are the most common tests to look for back injuries, problems with the alignment of the bones, and the general health of the intervertebral discs, which separate the spinal bones. X-Rays have many benefits, and some contraindications, with respect to radiation and lack of image detail, at least in relation to other more sophisticated tests such as MRI and CT Scan. Here's a brief overview.

X-Rays are black and white images that are developed at X-Ray photons pass through the body and hit an image receptor, producing an image of the internal structures of the body. X-rays are more likely to get absorbed by dense tissue, such as the bones and muscle, and pass through tissues of lower density, such as the skin, organs, and joints. As the X-rays pass through the patient and hit the image receptor, the image will blacken. In the areas behind the patient where more X-Rays photons are absorbed, the image will show up white. The image will also show up as various shades of grey in areas where some X-Ray photons have passed through the patient. The resulting image, made up of various shades of black, white, and grays should give doctors a good representation of the internal structures of the body.

So What do X-Rays really show? What do they not show? What Are the Risks? Why did the doctor order an X-Ray and not an MRI, CT Scan, or Ultrasound? Here we will try to answer all of these questions as best we can.

So what do X-Rays really show? The X-Rays images the bones really well. On an X-Rays, we can see the shape of the bones, enough detail to determine its density, and any possible pathology to the bones. Bone pathology may occur in the form of fractures, low bone density (osteoporosis) and misalignment of the bones in relation to one another. This misalignment of the bones may take the form of an abnormal lateral curvature of the spine (scoliosis) or when one vertebra slips in front of or behind the other and out of alignment (Spondylolisthesis). X-Rays also show joint dislocations, which often occur in the shoulder, knee, and hip joint, in which the bone has been forced out of the capsule of the joint.

X-Ray images indirectly give the doctors a lot of diagnostic information about the joints. On X-Rays, the outlines of bones and their detail are very well visualized, and the spaces between bones, if any, show up as dark. The bones of the spine are separated by joints known as intervertebral discs, and in a negative (no pathology) X-Ray the bones you will see an adequate separation of the bones. The space between the bones will show up as a dark grey or black.

What do they not show? In spine X-Rays, the presence of a dark space between the bones is evidence that it is there. If the disc is diseased, the space will be markedly narrowed, and in advanced disc disease the bones may even be contacting one another. The result of the bones coming in contact with one another may be serious damage to the bones, and the development of bone abnormalities such as bone spurs as the bones are continually degenerated and rebuilt.